The Roman Empire
The first conquests of the Roman Empire were in the East and immensely profitable. These old Mediterranean civilizations were rich and could afford much tribute. The profits funded new conquests.
Most of Italy was forested in BC 300. The newly cleared lands yielded large crops. The richness of the Italian soil was another basis of the Empire.
The western lands (Gaul, Spain, England, the Rhineland), which were conquered last, did not pay the costs of conquest. These lands were lightly settled and poor. While their soils were good, the cost of transporting crops like wheat overland was too great.
The Roman economy was overwhelmingly agricultural. Trade and industry were perhaps 10% of the economy. Once the conquests were over (about AD 1) agriculture had to pay the costs of administration.
A smallholder of the early Republic cultivated a hectare by hand with a hoe, growing olives, vines, fruit trees, grains, vegetables, forage crops and animals. The multistory canopy saved labor, reduced erosion, and was twice as productive in foodstuffs as plowing with an ox to grow grain. Some farmers applied manure, human manure, crushed limestone and ashes to their fields and grew cover crops on the grain fields left fallow every other year.
For large landowners plowing with oxen to grow grain was more profitable than hoe agriculture. While good farming practices were known, most large farmers didn’t follow them. In the two field system of the Greeks that was taken over by the Romans, land was plowed three times a year, whether cultivated or fallow, to control weeds. Erosion from plowland near Rome has been estimated at three quarters to four inches per century.
Iron had come into common use in Italy by BC 500 (for shovels, plow points and other tools) and forests were cut to smelt it, to fire pottery and burn brick. Trees were also cut for building material. Eroded soils from forests slid down the hillsides to the valley bottoms. Forests were often grazed after being cut.
As the more wealthy began to dominate Roman society after BC 200, large estates began to replace smallholdings, especially in the countryside around Rome. This landscape, the Campagna, fed the city until about BC 200.
Wheat, oil and wine could be profitably shipped by sea. The conquest of Egypt, with its soils renewed by the Nile, and the new lands of North Africa, let Rome feed itself after AD 1. The Imperial Middle East was completely deforested by AD 100 however and most of its upland soils were degraded by AD 200. Grazing replaced the cultivated grainland, which had replaced the forests. By the end of the Empire the silt carried by the Nile fed Rome. (The same African silt and the new lands of Sicily had also fed the declining Greek states 1000 years before.)
Land itself was taxed. No provision was made for varying yields. The government financed itself on a cash basis. Its single tax was inelastic and made it difficult to raise additional funds in time of need (as in war). Emperors in need of money debased the currency, an indirect tax.
Tenant farmers were taxed too highly to accumulate capital. When crops failed they abandoned their lands and left for Rome, where Egyptian wheat was distributed free to the citizens (the dole).
As more land fell into the hands of the large landowners, erosion increased. As yields fell, taxes became more difficult to pay and more and more land was abandoned. Abandoned land reached a third to a half of some provinces. Tax receipts collapsed. In AD 300 abandoned lands in the Campagna were estimated at 75,000 smallholdings. Taxes were doubled AD 324-364.
Eroded soil turned river valleys into marshlands. Malaria became a problem after AD 200. Malaria increases child mortality and reduces people’s capacity to work. In time, both slopes and valley bottoms were used for pasture rather than cultivated.
With the end of the conquests and the money they brought in, and the declining agricultural yields, and thus declining tax revenues, Rome no longer worked. The population of the Empire never recovered from the plague of the AD 160s. With the barbarian invasions of the AD 200s (crops destroyed, people killed and enslaved, animals killed or stolen), Rome began to go bankrupt. The literacy rate fell, but the size of the army and bureaucracy increased. The army was more and more staffed by barbarians.
As large estates further consolidated (city magistrates, whose position had become hereditary, had to pay the cost of city services), and plowed lands increased, yields fell further, and the countryside grew emptier. It now took ten times the land to feed a Roman than in the days of the early Republic. (Five hundred years of erosion would have reduced topsoil in the Campagna by 4 to 20 inches, and more on sloping lands.) Laws tied tenants to the land to prevent them from abandoning it. What the land needed to become productive was known; perhaps the larger structural problems of the Empire were also known. The western provinces were let go AD 260-274. By the late 300s, the Romans waited—as the poet Cavafy said—for the barbarians to deliver them from the Empire.
(In this essay I am indebted to The Collapse of Complex Societies by Joseph Tainter and Dirt by David Montgomery.)
Saturday, February 19, 2011
Thursday, February 10, 2011
Biology Comics
Barges
Recent figures indicate one gallon of diesel will move a ton of cargo 59 miles by truck, 202 miles by train, 514 miles by canal barge (a single barge can carry 3000 tons or 100 truck loads).
Barges use rivers as highways. They motor through the still waters behind the dams, passing each dam in locks. On the Rhine, narrow canal boats carrying bulk cargoes push their way upstream through the currents.
By converting rivers into highways dams interrupt the flow of water, sediment and detritus along the stream. Flooding riverside wetlands eliminates their capacity to remove nutrients from water flowing into the river. Dams prevent fish migrations (and thus migrations of mussels, their glochidia transported by swimming fish). The water above dams is warmer, that below dams (released from the bottom of the reservoir) colder, thus changing the temperature cues the eggs and larvae of riverine invertebrates and fish use for hatching and development. (So they grow too early or too late—both want to develop when abundant food of the right size is available). The levees with which dams are associated prevent floods and limit the spawning of fish, many species of which prefer to spawn on flooded habitats. Dams alter the timing and abundance of flows to ocean estuaries, upon which marine fish (many of which spawn in nearshore waters) depend. Silt and silicon stored behind dams change the relative abundance of algal species in estuaries; less sand downstream causes erosion of beaches.
Dams also let people harvest river water to drink, bathe, fill swimming pools; to use in industry; to cool power plants; to irrigate crops. Together with levees, dams let people farm riverside land (much of which was farmable before dams, with free fertility provided by the river); build houses and cities near the river; and use the river to move freight.
The Romans thought the air, the waters, the ocean, the shores of the sea could not be owned. Under the Public Trust Doctrine (which the United States received through English common law from Roman Law), public assets, such as shore and river banks, are held by government for the common good. Similarly, the authority of the state to regulate wildlife derives from its authority to protect common resources. It would be much simpler to see where these matters lead us if we depended more directly on an abundance of wildlife and fish. But we have extinguished both for the ‘common good’ of economic development.
While fossil fuels let us lead lives separate from nature, our dependence on nature is clear, if poorly understood. For instance, trees and photosynthetic bacteria maintain the oxygen levels in the atmosphere, microbes, fungi, and invertebrates recycle the carbon (the lignins and carbohydrates) the plants produce annually, and many interconnected systems maintain the climate. Our dependence on nature is a dependence on ecological process.
The ‘common welfare’ includes the taking of water from rivers for human use, the right of fish to water (so they remain a resource for fishers), the right of beaches to sand (so beach goers, and the owners of houses that back the beach, may enjoy them). In an ideal world, the beach deserves sand and the fish water (and water a place in rivers; and even oil a place in its underground reservoirs), whether or not any human advantage flows from them. (But the advantage is that a given system works in a more or less predictable way—which is not to say it cannot be disturbed—by volcanic eruptions cooling or warming the earth; by landslides damming rivers.)
Some rivers no longer reach the sea (the Colorado, the Yangtze). All their water is used by people. So marine fish are deprived of deltas and estuaries to spawn and mature in, offshore waters of nutrients. Many rivers no longer flood so native fish have trouble surviving (the Mississippi-Misssouri, the Colorado, the Rhine). Or are so polluted with silt and nutrients their fish (mussel, invertebrate, waterbird, turtle) populations crash and other organisms take over. The Illinois, a booming native fishery a century ago is now dominated by two filter feeding Chinese carp, escapees from fish farms, that thrive in the turbid water, and terrify boaters and water skiers by leaping up as they pass—part of the fishes’ strategy for escaping predators.
A rule of thumb for functioning rivers is that no more than 20-25% of longterm average flow should be withdrawn; and less during droughts.
Such numbers cannot be applied to rivers like the Colorado, all of whose water is subscribed to human use. (In fact, more Colorado water is allocated than exists, since the early 20th century years used as a benchmark to determine its flow were unusually wet ones).
Like the Mississippi-Missouri, the Columbia, or the Rhine (each remade in its own way), the Colorado is a totally remade river. Once silty and unpredictable, it now has long reaches of clear cold water and a more even flow. It is twice as salty as before. (The yearly flow of the river before dams varied from 4 million acre-feet to 24 million acre-feet, an enormous range; an acre-foot is the water necessary to cover an acre a foot deep.)
Large dams transformed the Colorado. Irrigation of rancher’s hayfields along its upstream tributaries began to change it. The concrete plug of Hoover Dam stopped any movement of fish upstream from the lower river. That part of the river, below the canyons, where the Yuma once planted their corn in the wet mud left by the receding floods (the corn matured in 60 days) flowed through an wide riparian valley of marshes and backwaters, fed on silt, rearranged by floods. The backwaters were places young pike-minnow and other native fish (razorback sucker, humpbacked sucker, bonytailed chub) matured. Pike-minnow were the top predatory fish in the Colorado, reaching 6 feet in length and 80 pounds. Pike-minnow spawned in the clean gravel and cobble left by the spring floods, matured in backwaters, migrated 300 miles up and down the river to seek optimal places for spawning and survival. Like the other fish of the Colorado and its tributaries they were adapted to the warm low silty flows of summer and the turbulent spring floods, when water volumes might increase by 100 times.
The marshes and backwaters along the lower river have been consolidated into a 150 yard wide stream held back by Parker dam at the Mexican border. The water irrigates fields on either side. Protected by dam operations and levees, houses have crept up to the edge of the river, which is no longer allowed to flood.
The Delta of the Colorado in the Gulf of California once consisted of 2 million acres of fresh and tidal wetlands. (Aldo Leopold wrote a memoir of a bow hunting trip there with his brother.) A desert delta, it was an important habitat for west coast waterbirds. Shrimp and other invertebrates of the delta supported the marine fish and birds of the Gulf of California. Now starved of silt and water (wet years in the 1980s restored about 150,0000 acres of the marshes), its place in the avian world has been taken over by the Salton Sea, a desert sink that was filled by the Colorado early in the 20th century when the river abandoned its normal course to take over an irrigation canal into California’s Imperial Valley. The water filled the sea during the several years it took to return the river to its bed. (That this had happened before is the subject of Native American tales.) The Salton Sea is now maintained by runoff from irrigated farms in the Imperial Valley (irrigated with Colorado water). Its increasing content of salts, fertilizers, metals and pesticides make it something of a disaster as a sanctuary for birds, which suffer (like the fish introduced from the gulf) from periodic epidemic diseases and dieoffs.
Allotting 5% of the Colorado water to the delta would restore a third of it (about 750,000 acres). Then plans to desalinate the Salton Sea (to maintain it as a bird habitat) could be abandoned and the money put into buying out water rights from farmers. Irrigation runoff would matter less, and farmers could shift to less water using, more valuable crops (say, to winter greens from alfalfa and cotton). All this would leave more water in the river, some of which would reach the delta.
Irrigation lets you ignore climate. Colorado water supports the alfalfa, cotton and lettuce fields of the Imperial Valley; the citrus plantations and spinach and cotton fields of Arizona. Many commodity crops (cotton, corn) grown under irrigation could be grown in sufficient quantity further east, with irrigation (if necessary) from streamside reservoirs dug beside the rivers. Small farmsize irrigation ponds store irrigation water, recharge underground aquifers, provide spawning places for fish and habitat for waterbirds and amphibians, especially if the water is pumped from shallow wells and not from the reservoirs themselves, with all their plant and animal life. Such reservoirs, storing no more than say 10% of the spring runoff, might improve the habitat of degraded eastern rivers. (Somewhat similarly, floodwaters from the Colorado could be stored in underground aquifers rather then in reservoirs behind dams, from which the water, exposed to the desert sun, evaporates.)
Drylands are often rich in nutrients which have been banked by plants and soil cyanobacteria, but not much used or leached by rain (nitrogen in dryland subsoils can reach toxic levels). Some dryland soils take to irrigation well. Many drylands however were once ocean bottom and are underlain by salts, which irrigation tends to draw upwards, and which must be constantly drained and flushed away. In the Wellton-Mohawk Irrigation District of Arizona, the Bureau of Reclamation sunk wells into the briny groundwater and piped it to the Colorado. Not allowed to raise the salt content of the river, they reduced its salt input in other ways—by lining canals, using more efficient irrigation systems, taking some lands with very salty subsoils out of production. I suppose if agriculture wouldn’t pay to desalinate the briny drainage water, marketing the salts and metals, and reusing the water for irrigation or returning it to the river, the agriculture wasn’t economic. But agriculture never pays the cost of large scale irrigation systems, which enrich private landowners with public monies, and degrade rivers.
Suppose for rivers like the Colorado we reverse the usual figure and say 25% of its water should be kept in the river to support its normal flood cycle and its wildlife. It is estimated that pressurized irrigation systems (drip tubing, sprinklers) that use less water (and more power but once you install the equipment solar power is free in the desert), shifting to crops of higher value that use less water (such as winter greens) and urban water conservation could save a third to a half of the water taken from the river. (The potential for household savings is huge but irrigation uses most of the water.) Then even more water could be left in the river and through a new treaty with Mexico, to whom the U.S. is currently obligated to release 1.5 million acre feet of Colorado water a year of a certain salinity (the last standard usually not met), the delta could be partially restored.
Rivers like the Colorado need to flood. Floods distribute sediment and nutrients to the floodplain, dig new channels and backwaters, renew the vegetation of cottonwood and willow. Floods maintain habitat for fish. The vegetation that sprouts on the newly bare ground feeds small mammals and water and game birds. While levels of heavy metals, pesticides and herbicides in the lower Colorado are high enough to cause reproductive problems in fish, the lack of floods and the changes in patterns of seasonal flow may be greater problems for the fish.
Glen Canyon Dam, the last major dam on the Colorado, was constructed to provide additional water storage for Lake Mead (the reservoir behind Hoover Dam). Evaporation from Lake Powell (the reservoir behind Glen Canyon Dam) is about a million acre-feet a year. Because of this, removing it would not cause much change in Lake Mead’s capacity to provide water. It’s removal would restore a more natural flow to a long reach of the river and let more water reach the delta. It would end the dam’s power generation (Glen Canyon Dam provides 3-4% of the electricity used in the four corners states); the power is useful because it can be switched on immediately when needed. It would also end the cold water fishery for rainbow trout below the dam (the trout feed on diatoms that thrive in the clear water) and the growing population of bald eagles that eat them. The silt behind Glen Canyon Dam is contaminated with mercury and selenium (as is the silt in Lake Mead), much of it leached from the basin’s sedimentary rocks. The dam also captures phosphorus (bound to the silt). The building of Glen Canyon Dam dramatically reduced the abundant artificial fishery in Lake Mead, which is based on phosphorus eating algae, algae eating gizzard shad and striped bass.
Letting the river flood below Hoover Dam would restore the lower river. Thanks to dam operations, levees and dredging, people now build up to the edge of the dredged river. About 123,000 acres of riparian vegetation remain along the lower Colorado (one fourth of the original), 23,000 of them in a natural state (5% of the original vegetation, then, the rest in introduced salt cedar which outcompetes cottonwoods and willows on salty, dry soils). Removing levees along contiguous parts of this (connecting the floodplain to the river) and letting the land flood would restore parts of the floodplain (then salt cedar is likely to become a part of the ecosystem, not a dominant). Some people would have to be bought out, which puts the government in the position of paying people to surrender what it paid to provide them.
A river disconnected from its flood plain no longer works. Without a floodplain, a river cannot store floodwaters, provide spawning habitat for fish, turn silt and nutrients into herbs and trees, adjust its bed to its flow and silt load, shelter abundant amphibians, song and water birds, and game animals, and provide water of an amount, timing, and with the nutrients, the fish and invertebrates in its delta expect.
By damming rivers and turning them into highways, we interfere with fundamental ecological process. Rivers can handle some interference but control beyond a point turns them into drains, barge highways, water delivery canals. Ecological process is what provides the fish and mussels in the river, the fish of the estuaries and the sea. Do people own the ecological processes that maintain our green world; or have a right to extinguish them?
We live more and more in a world separate from the rest of creation. The separate world always existed—all plants and animals create their own worlds, some more than others. The separate world became more so with cities and writing. It got a push forward with the printing press, the secularization of thought, the use of fossil fuels. Now most of us live in one separate world (that supported by fossil fuels), while scanning (through the internet) another. In these worlds what does nature matter? Who knows about it?
Moving freight by river barge takes less fuel but is biologically very expensive. If all the costs of maintaining the river as a highway were charged to the barges, it would be economically expansive too.
Human use and ownership of the landscape move along a continuum. One way to approach biological economics is to assign values to things (fish, forests, underground waters) that are extremely hard to value; and which receive very low values under modern economic theory (once used up, a resource will be replaced by something else); but whose loss is likely to have far-reaching effects (what will we drink?). I think an enlightened state should set biological limits through its interest in the common good; and let the cornucopian human economic society deal (as it will) with a much more limited landscape and resources.
(In this essay I am indebted to Restoring Colorado River Ecosystems by Robert Adler.)
Recent figures indicate one gallon of diesel will move a ton of cargo 59 miles by truck, 202 miles by train, 514 miles by canal barge (a single barge can carry 3000 tons or 100 truck loads).
Barges use rivers as highways. They motor through the still waters behind the dams, passing each dam in locks. On the Rhine, narrow canal boats carrying bulk cargoes push their way upstream through the currents.
By converting rivers into highways dams interrupt the flow of water, sediment and detritus along the stream. Flooding riverside wetlands eliminates their capacity to remove nutrients from water flowing into the river. Dams prevent fish migrations (and thus migrations of mussels, their glochidia transported by swimming fish). The water above dams is warmer, that below dams (released from the bottom of the reservoir) colder, thus changing the temperature cues the eggs and larvae of riverine invertebrates and fish use for hatching and development. (So they grow too early or too late—both want to develop when abundant food of the right size is available). The levees with which dams are associated prevent floods and limit the spawning of fish, many species of which prefer to spawn on flooded habitats. Dams alter the timing and abundance of flows to ocean estuaries, upon which marine fish (many of which spawn in nearshore waters) depend. Silt and silicon stored behind dams change the relative abundance of algal species in estuaries; less sand downstream causes erosion of beaches.
Dams also let people harvest river water to drink, bathe, fill swimming pools; to use in industry; to cool power plants; to irrigate crops. Together with levees, dams let people farm riverside land (much of which was farmable before dams, with free fertility provided by the river); build houses and cities near the river; and use the river to move freight.
The Romans thought the air, the waters, the ocean, the shores of the sea could not be owned. Under the Public Trust Doctrine (which the United States received through English common law from Roman Law), public assets, such as shore and river banks, are held by government for the common good. Similarly, the authority of the state to regulate wildlife derives from its authority to protect common resources. It would be much simpler to see where these matters lead us if we depended more directly on an abundance of wildlife and fish. But we have extinguished both for the ‘common good’ of economic development.
While fossil fuels let us lead lives separate from nature, our dependence on nature is clear, if poorly understood. For instance, trees and photosynthetic bacteria maintain the oxygen levels in the atmosphere, microbes, fungi, and invertebrates recycle the carbon (the lignins and carbohydrates) the plants produce annually, and many interconnected systems maintain the climate. Our dependence on nature is a dependence on ecological process.
The ‘common welfare’ includes the taking of water from rivers for human use, the right of fish to water (so they remain a resource for fishers), the right of beaches to sand (so beach goers, and the owners of houses that back the beach, may enjoy them). In an ideal world, the beach deserves sand and the fish water (and water a place in rivers; and even oil a place in its underground reservoirs), whether or not any human advantage flows from them. (But the advantage is that a given system works in a more or less predictable way—which is not to say it cannot be disturbed—by volcanic eruptions cooling or warming the earth; by landslides damming rivers.)
Some rivers no longer reach the sea (the Colorado, the Yangtze). All their water is used by people. So marine fish are deprived of deltas and estuaries to spawn and mature in, offshore waters of nutrients. Many rivers no longer flood so native fish have trouble surviving (the Mississippi-Misssouri, the Colorado, the Rhine). Or are so polluted with silt and nutrients their fish (mussel, invertebrate, waterbird, turtle) populations crash and other organisms take over. The Illinois, a booming native fishery a century ago is now dominated by two filter feeding Chinese carp, escapees from fish farms, that thrive in the turbid water, and terrify boaters and water skiers by leaping up as they pass—part of the fishes’ strategy for escaping predators.
A rule of thumb for functioning rivers is that no more than 20-25% of longterm average flow should be withdrawn; and less during droughts.
Such numbers cannot be applied to rivers like the Colorado, all of whose water is subscribed to human use. (In fact, more Colorado water is allocated than exists, since the early 20th century years used as a benchmark to determine its flow were unusually wet ones).
Like the Mississippi-Missouri, the Columbia, or the Rhine (each remade in its own way), the Colorado is a totally remade river. Once silty and unpredictable, it now has long reaches of clear cold water and a more even flow. It is twice as salty as before. (The yearly flow of the river before dams varied from 4 million acre-feet to 24 million acre-feet, an enormous range; an acre-foot is the water necessary to cover an acre a foot deep.)
Large dams transformed the Colorado. Irrigation of rancher’s hayfields along its upstream tributaries began to change it. The concrete plug of Hoover Dam stopped any movement of fish upstream from the lower river. That part of the river, below the canyons, where the Yuma once planted their corn in the wet mud left by the receding floods (the corn matured in 60 days) flowed through an wide riparian valley of marshes and backwaters, fed on silt, rearranged by floods. The backwaters were places young pike-minnow and other native fish (razorback sucker, humpbacked sucker, bonytailed chub) matured. Pike-minnow were the top predatory fish in the Colorado, reaching 6 feet in length and 80 pounds. Pike-minnow spawned in the clean gravel and cobble left by the spring floods, matured in backwaters, migrated 300 miles up and down the river to seek optimal places for spawning and survival. Like the other fish of the Colorado and its tributaries they were adapted to the warm low silty flows of summer and the turbulent spring floods, when water volumes might increase by 100 times.
The marshes and backwaters along the lower river have been consolidated into a 150 yard wide stream held back by Parker dam at the Mexican border. The water irrigates fields on either side. Protected by dam operations and levees, houses have crept up to the edge of the river, which is no longer allowed to flood.
The Delta of the Colorado in the Gulf of California once consisted of 2 million acres of fresh and tidal wetlands. (Aldo Leopold wrote a memoir of a bow hunting trip there with his brother.) A desert delta, it was an important habitat for west coast waterbirds. Shrimp and other invertebrates of the delta supported the marine fish and birds of the Gulf of California. Now starved of silt and water (wet years in the 1980s restored about 150,0000 acres of the marshes), its place in the avian world has been taken over by the Salton Sea, a desert sink that was filled by the Colorado early in the 20th century when the river abandoned its normal course to take over an irrigation canal into California’s Imperial Valley. The water filled the sea during the several years it took to return the river to its bed. (That this had happened before is the subject of Native American tales.) The Salton Sea is now maintained by runoff from irrigated farms in the Imperial Valley (irrigated with Colorado water). Its increasing content of salts, fertilizers, metals and pesticides make it something of a disaster as a sanctuary for birds, which suffer (like the fish introduced from the gulf) from periodic epidemic diseases and dieoffs.
Allotting 5% of the Colorado water to the delta would restore a third of it (about 750,000 acres). Then plans to desalinate the Salton Sea (to maintain it as a bird habitat) could be abandoned and the money put into buying out water rights from farmers. Irrigation runoff would matter less, and farmers could shift to less water using, more valuable crops (say, to winter greens from alfalfa and cotton). All this would leave more water in the river, some of which would reach the delta.
Irrigation lets you ignore climate. Colorado water supports the alfalfa, cotton and lettuce fields of the Imperial Valley; the citrus plantations and spinach and cotton fields of Arizona. Many commodity crops (cotton, corn) grown under irrigation could be grown in sufficient quantity further east, with irrigation (if necessary) from streamside reservoirs dug beside the rivers. Small farmsize irrigation ponds store irrigation water, recharge underground aquifers, provide spawning places for fish and habitat for waterbirds and amphibians, especially if the water is pumped from shallow wells and not from the reservoirs themselves, with all their plant and animal life. Such reservoirs, storing no more than say 10% of the spring runoff, might improve the habitat of degraded eastern rivers. (Somewhat similarly, floodwaters from the Colorado could be stored in underground aquifers rather then in reservoirs behind dams, from which the water, exposed to the desert sun, evaporates.)
Drylands are often rich in nutrients which have been banked by plants and soil cyanobacteria, but not much used or leached by rain (nitrogen in dryland subsoils can reach toxic levels). Some dryland soils take to irrigation well. Many drylands however were once ocean bottom and are underlain by salts, which irrigation tends to draw upwards, and which must be constantly drained and flushed away. In the Wellton-Mohawk Irrigation District of Arizona, the Bureau of Reclamation sunk wells into the briny groundwater and piped it to the Colorado. Not allowed to raise the salt content of the river, they reduced its salt input in other ways—by lining canals, using more efficient irrigation systems, taking some lands with very salty subsoils out of production. I suppose if agriculture wouldn’t pay to desalinate the briny drainage water, marketing the salts and metals, and reusing the water for irrigation or returning it to the river, the agriculture wasn’t economic. But agriculture never pays the cost of large scale irrigation systems, which enrich private landowners with public monies, and degrade rivers.
Suppose for rivers like the Colorado we reverse the usual figure and say 25% of its water should be kept in the river to support its normal flood cycle and its wildlife. It is estimated that pressurized irrigation systems (drip tubing, sprinklers) that use less water (and more power but once you install the equipment solar power is free in the desert), shifting to crops of higher value that use less water (such as winter greens) and urban water conservation could save a third to a half of the water taken from the river. (The potential for household savings is huge but irrigation uses most of the water.) Then even more water could be left in the river and through a new treaty with Mexico, to whom the U.S. is currently obligated to release 1.5 million acre feet of Colorado water a year of a certain salinity (the last standard usually not met), the delta could be partially restored.
Rivers like the Colorado need to flood. Floods distribute sediment and nutrients to the floodplain, dig new channels and backwaters, renew the vegetation of cottonwood and willow. Floods maintain habitat for fish. The vegetation that sprouts on the newly bare ground feeds small mammals and water and game birds. While levels of heavy metals, pesticides and herbicides in the lower Colorado are high enough to cause reproductive problems in fish, the lack of floods and the changes in patterns of seasonal flow may be greater problems for the fish.
Glen Canyon Dam, the last major dam on the Colorado, was constructed to provide additional water storage for Lake Mead (the reservoir behind Hoover Dam). Evaporation from Lake Powell (the reservoir behind Glen Canyon Dam) is about a million acre-feet a year. Because of this, removing it would not cause much change in Lake Mead’s capacity to provide water. It’s removal would restore a more natural flow to a long reach of the river and let more water reach the delta. It would end the dam’s power generation (Glen Canyon Dam provides 3-4% of the electricity used in the four corners states); the power is useful because it can be switched on immediately when needed. It would also end the cold water fishery for rainbow trout below the dam (the trout feed on diatoms that thrive in the clear water) and the growing population of bald eagles that eat them. The silt behind Glen Canyon Dam is contaminated with mercury and selenium (as is the silt in Lake Mead), much of it leached from the basin’s sedimentary rocks. The dam also captures phosphorus (bound to the silt). The building of Glen Canyon Dam dramatically reduced the abundant artificial fishery in Lake Mead, which is based on phosphorus eating algae, algae eating gizzard shad and striped bass.
Letting the river flood below Hoover Dam would restore the lower river. Thanks to dam operations, levees and dredging, people now build up to the edge of the dredged river. About 123,000 acres of riparian vegetation remain along the lower Colorado (one fourth of the original), 23,000 of them in a natural state (5% of the original vegetation, then, the rest in introduced salt cedar which outcompetes cottonwoods and willows on salty, dry soils). Removing levees along contiguous parts of this (connecting the floodplain to the river) and letting the land flood would restore parts of the floodplain (then salt cedar is likely to become a part of the ecosystem, not a dominant). Some people would have to be bought out, which puts the government in the position of paying people to surrender what it paid to provide them.
A river disconnected from its flood plain no longer works. Without a floodplain, a river cannot store floodwaters, provide spawning habitat for fish, turn silt and nutrients into herbs and trees, adjust its bed to its flow and silt load, shelter abundant amphibians, song and water birds, and game animals, and provide water of an amount, timing, and with the nutrients, the fish and invertebrates in its delta expect.
By damming rivers and turning them into highways, we interfere with fundamental ecological process. Rivers can handle some interference but control beyond a point turns them into drains, barge highways, water delivery canals. Ecological process is what provides the fish and mussels in the river, the fish of the estuaries and the sea. Do people own the ecological processes that maintain our green world; or have a right to extinguish them?
We live more and more in a world separate from the rest of creation. The separate world always existed—all plants and animals create their own worlds, some more than others. The separate world became more so with cities and writing. It got a push forward with the printing press, the secularization of thought, the use of fossil fuels. Now most of us live in one separate world (that supported by fossil fuels), while scanning (through the internet) another. In these worlds what does nature matter? Who knows about it?
Moving freight by river barge takes less fuel but is biologically very expensive. If all the costs of maintaining the river as a highway were charged to the barges, it would be economically expansive too.
Human use and ownership of the landscape move along a continuum. One way to approach biological economics is to assign values to things (fish, forests, underground waters) that are extremely hard to value; and which receive very low values under modern economic theory (once used up, a resource will be replaced by something else); but whose loss is likely to have far-reaching effects (what will we drink?). I think an enlightened state should set biological limits through its interest in the common good; and let the cornucopian human economic society deal (as it will) with a much more limited landscape and resources.
(In this essay I am indebted to Restoring Colorado River Ecosystems by Robert Adler.)
Friday, January 14, 2011
Biology Comics
Cornucopians and Malthusians
In 1980 Paul Ehrlich, a biologist (author of The Population Bomb), along with his colleagues the physicists John Harte and John Holdren, bet the economist Julian Simon on the future price of metals. Ehrlich bet the prices would increase as the better ores (those more accessible, with a higher metal content) were used up. Simon bet that metals would become cheaper and cheaper.
Simon won. In 1990 the prices of all five metals (copper, chromium, nickel, tin, tungsten) were lower.
While ores were poorer, processing methods became more efficient and the energy needed for processing got cheaper. The rise in metals prices (up to 1975) stimulated substitution of cheaper materials (as the use of plastic pipe instead of copper), which reduced demand for metals and kept their prices down (they had to compete).
Economics focuses on the human world. It teaches that the best use for resources is to exploit them as quickly as possible to economic extinction, then invest the profit in something else. As the resource becomes more scarce (and expensive) people will find alternatives and the human world will not suffer.
Malthusians point out that there is only so much of any resource (fresh water, ocean fish, fertile farmland, unpolluted air) and when they are gone what will we do. Some will be hard to substitute for.
Don’t worry, say the Malthusians—harvest the ocean for a tasty algal soup; adjust the climate to where we like it. If all else fails, we’re off to other worlds!
In the early nineteenth century Malthus’ concern was that population (which has the potential to grow geometrically) would always outgrow the supply of food (which grows slowly if at all). (The idea that animals produce far more young than can survive is one of the bases of evolution.) But at the time Malthus wrote the exploitation of fossil fuels was beginning. Fossil fuels let people build railroads to open up new farmland, ship food in steam powered steel ships all over the world, manufacture fertilizers, trawl distant seas. Over the next century and a half population grew by several times while world output (food and stuff) grew by several tens of times. Many more people became a lot more prosperous (even if some of them remain as poor as before). We could feed all those people a healthy diet even now, if food were fairly distributed.
So who’s right? Ehrlich? Simon? Both?
Simon refused to take a later bet Ehrlich proposed (his partner this time was the climatologist Stephen Schneider) in which Ehrlich focused on the resources themselves—the amount of fertile farmland per person, the extent of moist tropical forests, the global temperature, the number of species of plants and animals. Simon wouldn’t take the bet because he said that the degradation of the planet didn’t matter. Less farmland would be made up through fertilizer, or by producing food in other ways. The human habitat (the virtual world maintained by fossil fuels) would continue to improve. He used the analogy of the Olympics. While Ehrlich was betting the track would be worse, Simon was betting the times of the athletes would be better.
John Tierney, a journalist who writes a contrarian column in the Science Times of The New York Times recently described a bet with an oil expert, Matthew Simmons. In 2005 Simmons bet Tierney and his partner Rita Simon, Julian Simon’s widow, $5000 that the price of oil would average $200 or more in 2005 dollars in 2010. The price of oil rose to $145 by the summer of 2008 but fell with the global recession in the fall of 2008 to $50. The average price in 2010 was about $80. So again the cornucopians won (this time by chance).
Human affairs, like changes in climate, are unpredictable. I would bet Tierney that the level of carbon dioxide in the atmosphere in October 2015 measured from the Mauna Loa Observatory in Hawaii will be 398 ppmv or greater; that is, that carbon dioxide will continue to rise at 2 ppmv per year. Tierney, like Bjorn Lomborg, the skeptical environmentalist, thinks the effect of manmade carbon dioxide on climate will be minimal. (I could bet that one year between 2011 and 2015 will be either warmer or wetter, or both, than any since reliable measurements started in the 1880s.) Simon wouldn’t have taken my bet, because he wouldn’t have thought climatic conditions a matter of his concern. Human welfare was his concern, something that modern economies let prosper apart from nature.
I find it difficult to understand that the cornucopians feel no regret for the changes I see taking place all around me (collapsing songbird populations; strange fish in the rivers; butterflies, birds and fish moving north; lakes that don’t freeze; suburbs marching over the hills); or consider matters like terrible agricultural and forestry practices, acidifying seas, tropical forests going up in smoke or melting glaciers nothing to worry about.
I think all these (and related) things will affect the human world. I think the cornucopians are out of their minds. But they are likely to be correct up about our ability to take care of the human world, right up to the very end.
Up to the edge of the cliff.
Last year (2010) was the wettest in the historical record and tied 2005 as the hottest. I think we are seeing the future now.
In 1980 Paul Ehrlich, a biologist (author of The Population Bomb), along with his colleagues the physicists John Harte and John Holdren, bet the economist Julian Simon on the future price of metals. Ehrlich bet the prices would increase as the better ores (those more accessible, with a higher metal content) were used up. Simon bet that metals would become cheaper and cheaper.
Simon won. In 1990 the prices of all five metals (copper, chromium, nickel, tin, tungsten) were lower.
While ores were poorer, processing methods became more efficient and the energy needed for processing got cheaper. The rise in metals prices (up to 1975) stimulated substitution of cheaper materials (as the use of plastic pipe instead of copper), which reduced demand for metals and kept their prices down (they had to compete).
Economics focuses on the human world. It teaches that the best use for resources is to exploit them as quickly as possible to economic extinction, then invest the profit in something else. As the resource becomes more scarce (and expensive) people will find alternatives and the human world will not suffer.
Malthusians point out that there is only so much of any resource (fresh water, ocean fish, fertile farmland, unpolluted air) and when they are gone what will we do. Some will be hard to substitute for.
Don’t worry, say the Malthusians—harvest the ocean for a tasty algal soup; adjust the climate to where we like it. If all else fails, we’re off to other worlds!
In the early nineteenth century Malthus’ concern was that population (which has the potential to grow geometrically) would always outgrow the supply of food (which grows slowly if at all). (The idea that animals produce far more young than can survive is one of the bases of evolution.) But at the time Malthus wrote the exploitation of fossil fuels was beginning. Fossil fuels let people build railroads to open up new farmland, ship food in steam powered steel ships all over the world, manufacture fertilizers, trawl distant seas. Over the next century and a half population grew by several times while world output (food and stuff) grew by several tens of times. Many more people became a lot more prosperous (even if some of them remain as poor as before). We could feed all those people a healthy diet even now, if food were fairly distributed.
So who’s right? Ehrlich? Simon? Both?
Simon refused to take a later bet Ehrlich proposed (his partner this time was the climatologist Stephen Schneider) in which Ehrlich focused on the resources themselves—the amount of fertile farmland per person, the extent of moist tropical forests, the global temperature, the number of species of plants and animals. Simon wouldn’t take the bet because he said that the degradation of the planet didn’t matter. Less farmland would be made up through fertilizer, or by producing food in other ways. The human habitat (the virtual world maintained by fossil fuels) would continue to improve. He used the analogy of the Olympics. While Ehrlich was betting the track would be worse, Simon was betting the times of the athletes would be better.
John Tierney, a journalist who writes a contrarian column in the Science Times of The New York Times recently described a bet with an oil expert, Matthew Simmons. In 2005 Simmons bet Tierney and his partner Rita Simon, Julian Simon’s widow, $5000 that the price of oil would average $200 or more in 2005 dollars in 2010. The price of oil rose to $145 by the summer of 2008 but fell with the global recession in the fall of 2008 to $50. The average price in 2010 was about $80. So again the cornucopians won (this time by chance).
Human affairs, like changes in climate, are unpredictable. I would bet Tierney that the level of carbon dioxide in the atmosphere in October 2015 measured from the Mauna Loa Observatory in Hawaii will be 398 ppmv or greater; that is, that carbon dioxide will continue to rise at 2 ppmv per year. Tierney, like Bjorn Lomborg, the skeptical environmentalist, thinks the effect of manmade carbon dioxide on climate will be minimal. (I could bet that one year between 2011 and 2015 will be either warmer or wetter, or both, than any since reliable measurements started in the 1880s.) Simon wouldn’t have taken my bet, because he wouldn’t have thought climatic conditions a matter of his concern. Human welfare was his concern, something that modern economies let prosper apart from nature.
I find it difficult to understand that the cornucopians feel no regret for the changes I see taking place all around me (collapsing songbird populations; strange fish in the rivers; butterflies, birds and fish moving north; lakes that don’t freeze; suburbs marching over the hills); or consider matters like terrible agricultural and forestry practices, acidifying seas, tropical forests going up in smoke or melting glaciers nothing to worry about.
I think all these (and related) things will affect the human world. I think the cornucopians are out of their minds. But they are likely to be correct up about our ability to take care of the human world, right up to the very end.
Up to the edge of the cliff.
Last year (2010) was the wettest in the historical record and tied 2005 as the hottest. I think we are seeing the future now.
Sunday, October 31, 2010
Wildflower Portraits
Bloodroot (Sanguinaria canadensis)
A childhood book, Two Little Savages, pointed out the blue hepatica as the first woodland wild flower of spring. Hepaticas hide their heads among their three lobed leaves and only open their starry blue or pink blooms when they’re ready. The more eager bloodroots seem to open all at once, ten days of joyful white blossoms at the edge of the garden and scattered throughout the meadow. Their fat reddish roots (that bleed when cut) choke out other plants, but not all: dutchman’s breeches send up their lacy leaves and stems of nodding pantaloons from tiny bulbs that sit below the roots of the larger plant a few weeks later. Bloodroot grows along the river and some lowland streams in our area. Like false hellbore (which outcompetes it), it favors pockets of rich soil. I moved a single clump from the riverbank to my garden forty years ago and now it grows throughout my garden and much of my meadow, especially where the grass is thinner. So it does well enough in our uplands away from water though I have never seen it in the wild there. Perhaps it hasn’t reached more distant areas in its post glacial travels or perhaps clearing and cattle grazing on the uplands in the nineteenth century led to its retreat to the center of its distribution.
Bloodroot sets lots of seed in plump scimitar shaped pods that poke up under its leaves in June. The seeds must germinate well: ants or birds have spread the plant all over my garden and meadow. I usually however reproduce bloodroot by root division, which is simpler than from seed. The naked reddish rhizomes lie just under the ground. A clump is easily lifted to pot or put elsewhere in the garden. You must do this if the bloodroots are encroaching on your yellow lady’s slippers or trilliums. (Even some hostas are vulnerable.) Bloodroots do well in sun or shade in any garden soil. Their leaves start to look messy in July, when you may cut them off.
A childhood book, Two Little Savages, pointed out the blue hepatica as the first woodland wild flower of spring. Hepaticas hide their heads among their three lobed leaves and only open their starry blue or pink blooms when they’re ready. The more eager bloodroots seem to open all at once, ten days of joyful white blossoms at the edge of the garden and scattered throughout the meadow. Their fat reddish roots (that bleed when cut) choke out other plants, but not all: dutchman’s breeches send up their lacy leaves and stems of nodding pantaloons from tiny bulbs that sit below the roots of the larger plant a few weeks later. Bloodroot grows along the river and some lowland streams in our area. Like false hellbore (which outcompetes it), it favors pockets of rich soil. I moved a single clump from the riverbank to my garden forty years ago and now it grows throughout my garden and much of my meadow, especially where the grass is thinner. So it does well enough in our uplands away from water though I have never seen it in the wild there. Perhaps it hasn’t reached more distant areas in its post glacial travels or perhaps clearing and cattle grazing on the uplands in the nineteenth century led to its retreat to the center of its distribution.
Bloodroot sets lots of seed in plump scimitar shaped pods that poke up under its leaves in June. The seeds must germinate well: ants or birds have spread the plant all over my garden and meadow. I usually however reproduce bloodroot by root division, which is simpler than from seed. The naked reddish rhizomes lie just under the ground. A clump is easily lifted to pot or put elsewhere in the garden. You must do this if the bloodroots are encroaching on your yellow lady’s slippers or trilliums. (Even some hostas are vulnerable.) Bloodroots do well in sun or shade in any garden soil. Their leaves start to look messy in July, when you may cut them off.
Monday, August 23, 2010
Biology Comics
Aliens
My immigrant friend gets defensive when I brake and start pulling up purple loosestrife from the roadside. Another dastardly invasive, I say! What’s wrong with it, he says? It’s pretty!
We’re the invasives of course. Even the Indians only came here 10,000-30,000 years ago, some walking across the Bering Strait with their wary companions the moose and buffalo, others following the fish and manatees of the kelp beds around the coasts of Siberia and Alaska in skin boats. For them it was a new world too, with tame mammoths on the steppe, giant sloths lumbering across the Great Plains, a fruit eating rhinocerous in the forests of Central America.
Hunters and gatherers tend to live in the natural world, though they change it. Agricultural people have been taking apart ecosystems for the last 10,000 years. Industrial people have been creating entirely new worlds for 200.
Vertebrates (except herbivores) access much of the energy in sunlight through insects, which have more protein then beef. Herbivores eat plants (transformed sunlight) directly.
Frogs eat mosquitoes, songbirds caterpillars, falcons dragonflies, many birds beetles, the Everglade Kite snails (an invertebrate, not an insect). Mice eat insects, invertebrates and plants and are eaten by foxes, coyotes, hawks, owls, weasels and men. (Mouse skeletons have been found in fossilized human dung.)
Green plants, the terrestrial transformers of sunlight (let’s ignore the bacteria and archaea), engage in chemical warfare with each other and with the insects that graze on them. (Maybe 20% of the leaf mass of a forest tree is lost to leaf eating insects in a summer.)
The trees and other plants defend themselves by producing so called secondary metabolites (those chemicals not involved in their primary metabolism, that of converting sunlight and carbon dioxide to carbohydrate). These glycosides, phenols, terpenes and alkaloids affect the taste, digestibility and toxicity of plant leaves (and other parts). A caterpillar biting into an aspen leaf begins the production of tannins that will in hours make the leaf indigestible to it. The release of secondary metabolites into the air warns nearby trees of an insect infestation; they also begin producing defensive chemicals.
The insects evolve methods of detoxifying what the trees produce. Some make use of the toxins: thus monarch caterpillars store the glycosides produced by milkweed; the bitter taste of the butterfly keeps the birds from eating it: chemical warfare carried to the next generation.
Insects and plants thus coevolve, for tens of thousands or tens of millions of years. Perhaps 90% of herbivorous insects are thought to be specialists on a few species of plants, which they have evolved the capacity to eat (detoxifying their secondary metabolites). The rest are generalists, that take their chances.
New plants (say, asian rhododendrons in eastern North America) have chemical defenses to which the local insects are not adapted. The new plant thus has an advantage over the natives. New insects, diseases (meeting organisms without immunity), fungi, predators (meeting defenseless populations) and parasites may have similar advantages. The European genotype of Phragmites (giant reed) is eaten by 5 species of insects in the northeastern U.S. and by 170 in Europe, with the result that it is replacing the native strain of Phragmites (eaten by numerous native insects) here. The plants are the same species (they can interbreed) but have different chemical defenses (and their inedible offspring will be selected for).
Over 400 arthropods (insects and spiders) eat the Melaleuca tree in Australia, where it is rare, but 8 eat it in Florida, where it is far too common. (Over time, native insects will learn to eat Melaleuca and also the European Phragmites; but the time may be long.)
Europeans had a similar effect on their own species in the New World, as they brought with them the crowd diseases of the Eurasian agriculturalists to which the native peoples of the Americas had no immunity. So, in seventeenth century opinion, “the good hand of God” cleared the New World of its native peoples. (Europeans suffered a similar fate in Africa, where people and disease had been evolving together longest; approximately half the Europeans emigrating to West Africa died of disease in a year.)
Anyway, the point is that native plants are more edible to native insects and so produce up to 4 times the insect biomass of nonnative plants, and 35 times more caterpillars (a primary food of songbirds). They support a far greater biomass of insect eaters above them.
So I pull the (inedible) purple loosestrife out of the swamp.
Not all native species are equal. A hundred years ago the chestnut was the primary nut producer in the eastern forest (its production dwarfing that of the oaks and hickories). Its mast supported turkeys, deer, mice, squirrels, bears, decomposers, buffalo and people, and the caterpillars that fed on its tasty leaves supported huge populations of songbirds. The chestnut was killed by an imported fungus and its place (partly) taken by the tulip tree (a native), which supports little wildlife.
How to construct an ecosystem?
The problem is breaking ecosystems apart. In intact ecosystems aliens may establish a niche but are less likely become invasive. Their flowers and fruit may be used by the natives, even if their leaves are inedible. (In 10,000 years the leaves will become edible.)
Against some introductions— some predators, fungi, bacteria, insects, parasites, amphibians—there is no defense. For some time, as ships and planes spread plants and animals around, the world will become poorer (until, say, elms develop resistance to Dutch elm disease, American toads to chytrid fungus, chestnuts to chestnut blight).
As the abundant world fades, few will remember it.
Eventually a new world will blossom.
My immigrant friend gets defensive when I brake and start pulling up purple loosestrife from the roadside. Another dastardly invasive, I say! What’s wrong with it, he says? It’s pretty!
We’re the invasives of course. Even the Indians only came here 10,000-30,000 years ago, some walking across the Bering Strait with their wary companions the moose and buffalo, others following the fish and manatees of the kelp beds around the coasts of Siberia and Alaska in skin boats. For them it was a new world too, with tame mammoths on the steppe, giant sloths lumbering across the Great Plains, a fruit eating rhinocerous in the forests of Central America.
Hunters and gatherers tend to live in the natural world, though they change it. Agricultural people have been taking apart ecosystems for the last 10,000 years. Industrial people have been creating entirely new worlds for 200.
Vertebrates (except herbivores) access much of the energy in sunlight through insects, which have more protein then beef. Herbivores eat plants (transformed sunlight) directly.
Frogs eat mosquitoes, songbirds caterpillars, falcons dragonflies, many birds beetles, the Everglade Kite snails (an invertebrate, not an insect). Mice eat insects, invertebrates and plants and are eaten by foxes, coyotes, hawks, owls, weasels and men. (Mouse skeletons have been found in fossilized human dung.)
Green plants, the terrestrial transformers of sunlight (let’s ignore the bacteria and archaea), engage in chemical warfare with each other and with the insects that graze on them. (Maybe 20% of the leaf mass of a forest tree is lost to leaf eating insects in a summer.)
The trees and other plants defend themselves by producing so called secondary metabolites (those chemicals not involved in their primary metabolism, that of converting sunlight and carbon dioxide to carbohydrate). These glycosides, phenols, terpenes and alkaloids affect the taste, digestibility and toxicity of plant leaves (and other parts). A caterpillar biting into an aspen leaf begins the production of tannins that will in hours make the leaf indigestible to it. The release of secondary metabolites into the air warns nearby trees of an insect infestation; they also begin producing defensive chemicals.
The insects evolve methods of detoxifying what the trees produce. Some make use of the toxins: thus monarch caterpillars store the glycosides produced by milkweed; the bitter taste of the butterfly keeps the birds from eating it: chemical warfare carried to the next generation.
Insects and plants thus coevolve, for tens of thousands or tens of millions of years. Perhaps 90% of herbivorous insects are thought to be specialists on a few species of plants, which they have evolved the capacity to eat (detoxifying their secondary metabolites). The rest are generalists, that take their chances.
New plants (say, asian rhododendrons in eastern North America) have chemical defenses to which the local insects are not adapted. The new plant thus has an advantage over the natives. New insects, diseases (meeting organisms without immunity), fungi, predators (meeting defenseless populations) and parasites may have similar advantages. The European genotype of Phragmites (giant reed) is eaten by 5 species of insects in the northeastern U.S. and by 170 in Europe, with the result that it is replacing the native strain of Phragmites (eaten by numerous native insects) here. The plants are the same species (they can interbreed) but have different chemical defenses (and their inedible offspring will be selected for).
Over 400 arthropods (insects and spiders) eat the Melaleuca tree in Australia, where it is rare, but 8 eat it in Florida, where it is far too common. (Over time, native insects will learn to eat Melaleuca and also the European Phragmites; but the time may be long.)
Europeans had a similar effect on their own species in the New World, as they brought with them the crowd diseases of the Eurasian agriculturalists to which the native peoples of the Americas had no immunity. So, in seventeenth century opinion, “the good hand of God” cleared the New World of its native peoples. (Europeans suffered a similar fate in Africa, where people and disease had been evolving together longest; approximately half the Europeans emigrating to West Africa died of disease in a year.)
Anyway, the point is that native plants are more edible to native insects and so produce up to 4 times the insect biomass of nonnative plants, and 35 times more caterpillars (a primary food of songbirds). They support a far greater biomass of insect eaters above them.
So I pull the (inedible) purple loosestrife out of the swamp.
Not all native species are equal. A hundred years ago the chestnut was the primary nut producer in the eastern forest (its production dwarfing that of the oaks and hickories). Its mast supported turkeys, deer, mice, squirrels, bears, decomposers, buffalo and people, and the caterpillars that fed on its tasty leaves supported huge populations of songbirds. The chestnut was killed by an imported fungus and its place (partly) taken by the tulip tree (a native), which supports little wildlife.
How to construct an ecosystem?
The problem is breaking ecosystems apart. In intact ecosystems aliens may establish a niche but are less likely become invasive. Their flowers and fruit may be used by the natives, even if their leaves are inedible. (In 10,000 years the leaves will become edible.)
Against some introductions— some predators, fungi, bacteria, insects, parasites, amphibians—there is no defense. For some time, as ships and planes spread plants and animals around, the world will become poorer (until, say, elms develop resistance to Dutch elm disease, American toads to chytrid fungus, chestnuts to chestnut blight).
As the abundant world fades, few will remember it.
Eventually a new world will blossom.
Friday, August 6, 2010
Biology Comics
Biochar and Silicate Rocks
Heavy rains are increasing, Arctic ice is melting, Russian peat bogs are burning, methane is bubbling out of the East Siberian Sea, the summer’s heat and humidity grows and grows. Alone each means nothing, together they add up to a changing climate, which only demagogs and idiots ignore.
Of course it may all turn around and (especially here in the U.S. northeast) turn cold for the next 1000 years. We are poking the climate beast, with unpredictable results, as Wallace Broecker remarks.
The problem is too much carbon dioxide (and other heat trapping gases, such as methane, nitrous oxide and the chlorofluorocarbons) in the atmosphere. And too much soot and black carbon in the air and falling out on Arctic ice.
We’re putting the gases (and the soot and dust) there. Since modern life runs on fossil fuels, we aren’t likely to stop; or stop fast enough. Is anyone going to make China stop? Or India? Or the U.S. for that matter?
Saving energy is boring, nuclear power risky, wind and solar are expensive and require storage schemes (pumped water reservoirs, chemical batteries) that are expensive, destructive or dangerous. Forget about sequestering carbon from smokestacks, it’s too complicated, it takes too much energy, it’s a pipe dream. What free lunch?
So what about continuing to dig up coal and geoengineer the planet? Launch tiny mirrors into the atmosphere to reflect sunlight back to space. (Of course the ocean and atmosphere would continue to acidify.) Spray sulfur dioxide from planes into the stratosphere to reflect sunlight, or hey!—just remove the controls on sulfur from fossil fuels. Or spray seawater into the atmosphere to increase the reflectivity of clouds. Or pump seawater onto Arctic ice to thicken it. (Why not, to the last two.)
Lime the planet to counter acid rain!
The main downside of schemes to reduce incoming sunlight is that the planet will continue to acidify. As for spraying sulfur dioxide, the sulfur dioxide will eventually fall out on the land and ocean. There are probably other downsides—changes in rainfall or airflow, changes in stratospheric chemistry or the growth rate of plants. To think all such effects are predictable is nonsense.
So what about taking carbon dioxide directly from the air. One idea is to fertilize the oceans with urea (a nitrogen fertilizer), or finely ground iron (a limiting nutrient in the sea), or by installing huge pipes to increase the transfer of nutrients from deep water (where they are common) to the sunlit surface (where they fuel algal growth). The fertilized algae on the surface divide and grow, are eaten by fish (or die), and sink as tiny corpses or fish poop to the bottom of the ocean where the carbon (taken by the algae from the air) is locked up for thousands of years. Unfortunately, fertilization schemes don’t seem to work (the carbon stored is negligible compared to the effort put into fertilization). Their other effects on the sea are also unknown.
On the other hand, our overfishing of the oceans (a natural result of unregulated capitalistic effort) is reducing them to ecosystems of algae and jellyfish, while our heavy fertilization of large continental watersheds, with the resulting dead zones of maximized algal growth at the mouths of major rivers, may be storing more carbon than we realize. (The oil in farm fertilizer producing more oil in sediments.) Of course destroying the oceans to save the planet is nuts.
What to do? Well all that boring stuff (fast breeder reactors, reducing population, cars that get 200 miles to the gallon, insulating houses, reducing poverty, empowering poor women—both the last tend to reduce population growth) helps. Reforesting or revegetating degraded lands stores carbon in soils, plants and trees. Reducing numbers of cattle and sheep on overgrazed lands (say in the U.S. Great Basin and High Plains) lets shrubs and perennial grasses store carbon in soils. So does rotational grazing of dairy cattle on eastern or midwestern pastures. Proper management of croplands lets them store some carbon (or lose less). Some writers claim the soils’ carbon stores are full after 15-30 years, but soil storage capacity undoubtedly varies with the site.
Reforesting degraded lands lets trees store carbon in their tissues and in the soil. Billions of acres of degraded lands are candidates for reforestation: much of the Mediterranean basin, including the mountainous islands; much of China; the Tibetan plateau; the Andean altiplano (both were deforested by people thousands of years ago for their crops and animals); the Himalayan foothills; much of the U.S. Southeast and Midwest; some deserts.
In the Sahel in the 1970s, millet farmers let acacia trees grow in their fields. This was a folk technique that had been mocked by modern agronomists. The trees provided forage for the animals, which meant more manure for the crops. More trees grew, sprouting in the dung of the (more numerous) grazing animals. This let the farmers raise more animals, which meant more dung and more cropland. Eventually several million acres of the Sahel were reclaimed for agriculture. The trees store carbon in the soil and have slightly increased rainfall over the northern Sahel.
The huarango tree of the Atacama Desert in Peru (one of the driest places in the world) captures water from ocean mists. Its roots draw up water from 150 feet down. It breaks the wind over the desert and, by condensing mists, moistens (slightly) the upper layers of the soil. It lives a millennium and (a mesquite) produces a sweet edible pod, which can be used for fodder, ground into flour, or made into a syrup or beer. Its fragrant blossoms support bees. The Nazca of 1500 years ago cut down huarangos to plant irrigated cotton and corn in the river valleys, exposing the desert to floods and wind erosion. Modern residents of the Atacama cut the trees for firewood. The tree is thorny, not particularly attractive, and invasive where successful and could support a life based on carbon storage, goats, honey and beer.
Agricultural revegetation of degraded lands (acacia trees, camels and millet; salicornia, a forage crop irrigable with seawater; huarango trees; jojoba, a shrub with oil bearing seeds; grapevines; mangoes; pomegranates; other fruit and nut trees) lets carbon accumulate in soils. If the prunings from the trees and the crop wastes are converted to charcoal (biochar) and spread on farmland (where the char promotes plant growth) their carbon will be stored for tens of thousands of years. (Perhaps 50,000 years: this will work in industrial agriculture; with poor peasant farmers, the charcoal will be used for cooking.)
Turning the crop residues of industrial agriculture into biochar would store billions of tons of carbon a year. Estimates range from 1-2 billion tons a year. (We release 8-9 billion tons of carbon as carbon dioxide a year to the atmosphere.) The equipment to turn corn stalks or wheat straw into charcoal is cheap, the process simple. Since biochar makes an excellent fertilizer, and reduces fertilizer runoff, the equipment would pay for itself in a year or two.
Revegetated forestlands store carbon in the trees and in the soil. The carbon in the trees is released to the atmosphere when the trees are cut (most processed trees return as carbon to the atmosphere in ten years); or when they die and decay. While growing, the forests continue to store carbon (say, for 300-2000 years). When storage slows, the best way to cut the trees is selectively, so as to expose the soil as little as possible to sunlight, which speeds up its losses of carbon. The best bottom log could be used as sawn lumber (a carbon loss, factored into any payments for carbon storage; but the trunk represents only a fraction of the tree’s mass) and the rest converted to biochar and spread back on the forest; or sold to spread on farmland. If landowners are to be paid for storing carbon, the way to maximize a forest’s carbon storage would have to be worked out; and calculated by the year or decade. We have 300 years to do that. Any payments for carbon storage should be based on real numbers, not guesses. Payments from, say, a tax on fossil fuels.
Changing agricultural practices to capture carbon; revegetating degraded lands; producing biochar involve no downsides of which I am aware. Such practices would produce a return on investment and improve the nutrient storage capacity of watersheds, and thus improve the health of riverine and ocean fisheries. We might store a quarter of the carbon dioxide we currently produce by such methods, perhaps more.
One other technique offers carbon storage, but with a limited downside. This involves capturing carbon dioxide through its natural (exothermic) reaction with magnesium oxide or calcium oxide rocks. The reaction forms stable carbonates (limestones). One can foster this reaction by mining and grinding the rocks and spreading them on land or on the sea. The energy involved in the mining and pulverizing is inconsequential in comparison with the carbon stored. Spreading the powder on the ocean (especially over the productive continental shelves) lets one reduce the acidification of the sea as well as capture carbon dioxide from the air. (A free lunch?) One picks cliffs of the appropriate rocks on a seacoast (volcanic rocks are good), sets up a mine and sends the powder down to slow moving ships that spread it over the sea. (Schemes like this have been suggested for the Scottish coast to produce builders gravel.)
In biologically appropriate situations, the mine could be made into a pit for pumped storage of seawater (another munch at lunch). This isn’t appropriate where marine life would be harmed, thus not, say, on the Palisade escarpment north of New York City, above the Hudson estuary, where the rock is appropriate and the pumped storage capacity could use the photovoltaic output of the city, but the damage to the estuary would likely be great.
The variability of solar power means it has to be backed up. The power supply for a modern grid cannot be interrupted or the system will crash. Since the output from the sun and wind is unpredictable, one must either invest in double the capacity—the fossil or nuclear fuelled grid as well as the unreliable photovoltaic or wind capacity— or have some storage that can be switched on when the solar supply falters. Flywheels; chemical batteries; compressed air in abandoned mines; pumped storage all work. Pumped water from the sea is a natural (say, on Oahu in Hawaii; in the Canaries; in California or Maine; in Scotland). A pumped storage scheme was suggested for Storm King Mountain on the Hudson in the late sixties but was abandoned after an outcry from environmentalists (me included). The high dams on the ruined rivers of the U.S. west (the Colorado, the Yellowstone, the Columbia) offer obvious sites for pumped storage: all they lack are the pumps and a safe way (for the riverine biota) to pump sufficient volumes of water back up behind the dams. (A nonbiologically invasive way to extract water from rivers would make many things better.)
Of course, the ultimate solution to climate change is fewer people, saving energy, fast breeder reactors, the electrification of transport and the energy supply (so all energy can be provided by the sun). Alleviating poverty and empowering women, the projects of the “skeptical environmentalist,” a foolish and publicity hungry Dane, will also reduce population.
Let’s do it all! Make biochar, mine silicate rocks, have one child, and plant trees.
Heavy rains are increasing, Arctic ice is melting, Russian peat bogs are burning, methane is bubbling out of the East Siberian Sea, the summer’s heat and humidity grows and grows. Alone each means nothing, together they add up to a changing climate, which only demagogs and idiots ignore.
Of course it may all turn around and (especially here in the U.S. northeast) turn cold for the next 1000 years. We are poking the climate beast, with unpredictable results, as Wallace Broecker remarks.
The problem is too much carbon dioxide (and other heat trapping gases, such as methane, nitrous oxide and the chlorofluorocarbons) in the atmosphere. And too much soot and black carbon in the air and falling out on Arctic ice.
We’re putting the gases (and the soot and dust) there. Since modern life runs on fossil fuels, we aren’t likely to stop; or stop fast enough. Is anyone going to make China stop? Or India? Or the U.S. for that matter?
Saving energy is boring, nuclear power risky, wind and solar are expensive and require storage schemes (pumped water reservoirs, chemical batteries) that are expensive, destructive or dangerous. Forget about sequestering carbon from smokestacks, it’s too complicated, it takes too much energy, it’s a pipe dream. What free lunch?
So what about continuing to dig up coal and geoengineer the planet? Launch tiny mirrors into the atmosphere to reflect sunlight back to space. (Of course the ocean and atmosphere would continue to acidify.) Spray sulfur dioxide from planes into the stratosphere to reflect sunlight, or hey!—just remove the controls on sulfur from fossil fuels. Or spray seawater into the atmosphere to increase the reflectivity of clouds. Or pump seawater onto Arctic ice to thicken it. (Why not, to the last two.)
Lime the planet to counter acid rain!
The main downside of schemes to reduce incoming sunlight is that the planet will continue to acidify. As for spraying sulfur dioxide, the sulfur dioxide will eventually fall out on the land and ocean. There are probably other downsides—changes in rainfall or airflow, changes in stratospheric chemistry or the growth rate of plants. To think all such effects are predictable is nonsense.
So what about taking carbon dioxide directly from the air. One idea is to fertilize the oceans with urea (a nitrogen fertilizer), or finely ground iron (a limiting nutrient in the sea), or by installing huge pipes to increase the transfer of nutrients from deep water (where they are common) to the sunlit surface (where they fuel algal growth). The fertilized algae on the surface divide and grow, are eaten by fish (or die), and sink as tiny corpses or fish poop to the bottom of the ocean where the carbon (taken by the algae from the air) is locked up for thousands of years. Unfortunately, fertilization schemes don’t seem to work (the carbon stored is negligible compared to the effort put into fertilization). Their other effects on the sea are also unknown.
On the other hand, our overfishing of the oceans (a natural result of unregulated capitalistic effort) is reducing them to ecosystems of algae and jellyfish, while our heavy fertilization of large continental watersheds, with the resulting dead zones of maximized algal growth at the mouths of major rivers, may be storing more carbon than we realize. (The oil in farm fertilizer producing more oil in sediments.) Of course destroying the oceans to save the planet is nuts.
What to do? Well all that boring stuff (fast breeder reactors, reducing population, cars that get 200 miles to the gallon, insulating houses, reducing poverty, empowering poor women—both the last tend to reduce population growth) helps. Reforesting or revegetating degraded lands stores carbon in soils, plants and trees. Reducing numbers of cattle and sheep on overgrazed lands (say in the U.S. Great Basin and High Plains) lets shrubs and perennial grasses store carbon in soils. So does rotational grazing of dairy cattle on eastern or midwestern pastures. Proper management of croplands lets them store some carbon (or lose less). Some writers claim the soils’ carbon stores are full after 15-30 years, but soil storage capacity undoubtedly varies with the site.
Reforesting degraded lands lets trees store carbon in their tissues and in the soil. Billions of acres of degraded lands are candidates for reforestation: much of the Mediterranean basin, including the mountainous islands; much of China; the Tibetan plateau; the Andean altiplano (both were deforested by people thousands of years ago for their crops and animals); the Himalayan foothills; much of the U.S. Southeast and Midwest; some deserts.
In the Sahel in the 1970s, millet farmers let acacia trees grow in their fields. This was a folk technique that had been mocked by modern agronomists. The trees provided forage for the animals, which meant more manure for the crops. More trees grew, sprouting in the dung of the (more numerous) grazing animals. This let the farmers raise more animals, which meant more dung and more cropland. Eventually several million acres of the Sahel were reclaimed for agriculture. The trees store carbon in the soil and have slightly increased rainfall over the northern Sahel.
The huarango tree of the Atacama Desert in Peru (one of the driest places in the world) captures water from ocean mists. Its roots draw up water from 150 feet down. It breaks the wind over the desert and, by condensing mists, moistens (slightly) the upper layers of the soil. It lives a millennium and (a mesquite) produces a sweet edible pod, which can be used for fodder, ground into flour, or made into a syrup or beer. Its fragrant blossoms support bees. The Nazca of 1500 years ago cut down huarangos to plant irrigated cotton and corn in the river valleys, exposing the desert to floods and wind erosion. Modern residents of the Atacama cut the trees for firewood. The tree is thorny, not particularly attractive, and invasive where successful and could support a life based on carbon storage, goats, honey and beer.
Agricultural revegetation of degraded lands (acacia trees, camels and millet; salicornia, a forage crop irrigable with seawater; huarango trees; jojoba, a shrub with oil bearing seeds; grapevines; mangoes; pomegranates; other fruit and nut trees) lets carbon accumulate in soils. If the prunings from the trees and the crop wastes are converted to charcoal (biochar) and spread on farmland (where the char promotes plant growth) their carbon will be stored for tens of thousands of years. (Perhaps 50,000 years: this will work in industrial agriculture; with poor peasant farmers, the charcoal will be used for cooking.)
Turning the crop residues of industrial agriculture into biochar would store billions of tons of carbon a year. Estimates range from 1-2 billion tons a year. (We release 8-9 billion tons of carbon as carbon dioxide a year to the atmosphere.) The equipment to turn corn stalks or wheat straw into charcoal is cheap, the process simple. Since biochar makes an excellent fertilizer, and reduces fertilizer runoff, the equipment would pay for itself in a year or two.
Revegetated forestlands store carbon in the trees and in the soil. The carbon in the trees is released to the atmosphere when the trees are cut (most processed trees return as carbon to the atmosphere in ten years); or when they die and decay. While growing, the forests continue to store carbon (say, for 300-2000 years). When storage slows, the best way to cut the trees is selectively, so as to expose the soil as little as possible to sunlight, which speeds up its losses of carbon. The best bottom log could be used as sawn lumber (a carbon loss, factored into any payments for carbon storage; but the trunk represents only a fraction of the tree’s mass) and the rest converted to biochar and spread back on the forest; or sold to spread on farmland. If landowners are to be paid for storing carbon, the way to maximize a forest’s carbon storage would have to be worked out; and calculated by the year or decade. We have 300 years to do that. Any payments for carbon storage should be based on real numbers, not guesses. Payments from, say, a tax on fossil fuels.
Changing agricultural practices to capture carbon; revegetating degraded lands; producing biochar involve no downsides of which I am aware. Such practices would produce a return on investment and improve the nutrient storage capacity of watersheds, and thus improve the health of riverine and ocean fisheries. We might store a quarter of the carbon dioxide we currently produce by such methods, perhaps more.
One other technique offers carbon storage, but with a limited downside. This involves capturing carbon dioxide through its natural (exothermic) reaction with magnesium oxide or calcium oxide rocks. The reaction forms stable carbonates (limestones). One can foster this reaction by mining and grinding the rocks and spreading them on land or on the sea. The energy involved in the mining and pulverizing is inconsequential in comparison with the carbon stored. Spreading the powder on the ocean (especially over the productive continental shelves) lets one reduce the acidification of the sea as well as capture carbon dioxide from the air. (A free lunch?) One picks cliffs of the appropriate rocks on a seacoast (volcanic rocks are good), sets up a mine and sends the powder down to slow moving ships that spread it over the sea. (Schemes like this have been suggested for the Scottish coast to produce builders gravel.)
In biologically appropriate situations, the mine could be made into a pit for pumped storage of seawater (another munch at lunch). This isn’t appropriate where marine life would be harmed, thus not, say, on the Palisade escarpment north of New York City, above the Hudson estuary, where the rock is appropriate and the pumped storage capacity could use the photovoltaic output of the city, but the damage to the estuary would likely be great.
The variability of solar power means it has to be backed up. The power supply for a modern grid cannot be interrupted or the system will crash. Since the output from the sun and wind is unpredictable, one must either invest in double the capacity—the fossil or nuclear fuelled grid as well as the unreliable photovoltaic or wind capacity— or have some storage that can be switched on when the solar supply falters. Flywheels; chemical batteries; compressed air in abandoned mines; pumped storage all work. Pumped water from the sea is a natural (say, on Oahu in Hawaii; in the Canaries; in California or Maine; in Scotland). A pumped storage scheme was suggested for Storm King Mountain on the Hudson in the late sixties but was abandoned after an outcry from environmentalists (me included). The high dams on the ruined rivers of the U.S. west (the Colorado, the Yellowstone, the Columbia) offer obvious sites for pumped storage: all they lack are the pumps and a safe way (for the riverine biota) to pump sufficient volumes of water back up behind the dams. (A nonbiologically invasive way to extract water from rivers would make many things better.)
Of course, the ultimate solution to climate change is fewer people, saving energy, fast breeder reactors, the electrification of transport and the energy supply (so all energy can be provided by the sun). Alleviating poverty and empowering women, the projects of the “skeptical environmentalist,” a foolish and publicity hungry Dane, will also reduce population.
Let’s do it all! Make biochar, mine silicate rocks, have one child, and plant trees.
Thursday, July 22, 2010
Biology Comics
Suburbs are for the Birds!
In an earlier Comic I mentioned the local cowbirds terrorized by sharpshinned hawks and merlins. The cowbirds lay their eggs in the nests of other birds and let them raise their young; the growing cowbirds push the competing young out of the nest. Over the last century cowbirds have spread from the plains and prairies east into the artificial human prairie that has replaced the eastern forest in North America and (along with midsized predators like raccoons, opossums, house cats and skunks) have helped reduce songbirds populations by 50% or more (habitat change and industrial pollution also helped). When I moved to the Adirondacks in 1972 the spring sighting of a male cowbird gurgling from the top of our bare apple tree, the glossy black singer perched above his two dove gray companions, made me smile. The cowbird was a common bird in central New York, where I grew up, but (like the raven or the turkey vulture) uncommon in the Adirondacks in the 1950s.
While doing his laundry in a nearby village a friend watched a merlin (a fierce little falcon the size of a robin) harassing the starlings that nested in the eves of the laundromat. Merlins were extremely uncommon 40-50 years ago but over the last decade have been on a roll.
Until fairly recently it was legal to shoot hawks (many of them ate domestic chickens and ducks) and in the early twentieth century thousands were shot each fall as they slid south on air currents above Appalachian ridges, or cruised along Atlantic beaches. Walkers in the woods shot them. Pennsylvania had a $5 bounty on goshawks in the 1930s (not a small sum at the time) when Hawk Mountain Sanctuary was established. Bird books from the early twentieth century debated which raptors should be eliminated: usually the verdict fell on the bird killers, the three short winged hunters of the forest, the sharpshin, the Cooper’s hawk, the goshawk, birds of similar form and abilities in different sizes. The merlin’s rarity made it unimportant. The writers of the books were ornithologists (they favored more songbirds). The story is the same as for mountain lions and wolves (to which many hawks were compared): shot to save the deer.
These books have tales from when hawks were more abundant. Goshawks, the largest of the accepters (and thus the least common, but commonly seen) would strike a rabbit or a hen with such force that the animal’s side would be torn off. When shot at while striking a hen, a goshawk would attack the man with the gun. In thick cover they would bound under trees after rabbits they had missed. Anything that flew or ran was fair game. One battle between a goshawk and a barred owl ended with both birds dead, the owl bleeding to death, the goshawk beheaded.
Large hunters are used to getting their way. They don’t like to be told what to do. Their fierceness helps them survive.
Hawks also suffered from eggshell thinning during the age of DDT (1945-1972 in the United States; approximately the economic life of the manufacturing facility). DDT interfered with calcium metabolism in birds; the result was eggshells that broke under the weight of a brooding bird. Not only hawks suffered, smaller birds did also, but being at the top of long food chains that accumulated the chemical, hawks suffered the most. Peregrine falcons more or less disappeared from Great Britain and the eastern United States. Goshawks, which eat gamebirds and small mammals, which eat leaves, berries and grass (thus situated at the end of shorter foodchains), suffered less.
Lately other chemicals, including other industrial chlorinated hydrocarbons that act as hormone mimics, like DDT, and heavy metals like mercury, a neurotoxin released by burning coal, have become problems for some birds (gulls, cormorants, thrushes); but some raptors seem to be increasing.
Not only hawks were more abundant. Flocks of black billed cuckoos followed infestations of tent caterpillars and would clear small orchards of their nests in a day. One of the common names for the rose breasted grosbeak was potato bug bird; but I have never seen grosbeaks eating potato bugs (or in numbers that could eat enough to help). Cuckoos are now rather uncommon and the silken nests of tent caterpillars on roadside trees (most birds won’t eat the hairy adults) go unmolested.
Such stories make one suspect that populations of North American breeding birds are really down 90-95% from the time of European settlement.
Conservationists who want to restore large animals speak of the three Cs: cores, corridors, carnivores. Cores are ecosystems restored as much as possible to their wild state (thus without people in the developed world). Corridors connect cores, turning separate populations of plants and animals into metapopulations. Carnivores influence the growth of plants and the abundance and types of animals and so are necessary for the health of cores.
This influence of carnivores happens on all size levels, from microbes to moose. Large carnivores influence forest succession by eating large herbivores like deer and moose, which through their feeding habits influence forest succession and the plants of the forest floor. Large carnivores also eat midsized carnivores (their competition; or a tasty snack) and so influence songbird numbers. (Many so called mid size predators are nest predators of songbirds.)
The same is true in birds. Large raptors like goshawks eat crows (a nest robber, also on the increase since shooting of crows has been regulated) as well as rabbits and squirrels. Some great horned owls specialize in crows, which roost communally. Thus one sees flocks of crows roosting at night in the bright lights near malls or superhighways. Smaller raptors eat jays (another nest predator) as well birds the size of starlings and waxwings and also smaller ones like indigo buntings, house wrens and English sparrows.
North Americans are unlikely to live with mountain lions or wolves, despite the fact that deer, which are involved in 1.5 million car accidents yearly in North America, kill many more people than either. (Mountain lions will stalk and kill people but wolves, at least in North America, avoid them.) From a purely utilitarian point of view, we would be better off if mountain lions were abundant enough to control deer numbers and so reduce the number of people killed in collisions with deer (about 225 annually), even if the lions killed 10-20 people a year.
But the emotional difference between dying from a collision with a long legged herbivore that dashes into the road and from being stalked by a large cat that pounces on you from behind, breaks your neck, opens your chest and eats your heart and lungs, is of course considerable.
North Americans may manage to live with coyotes (many millions of Los Angelenos already do), which kill feral (and pet) cats, a major predator of songbirds (and keep many house cats, terrified, indoors). Coyotes have a major influence on songbird populations in Californian canyons: where there are coyotes there are songbirds, where not, not. Coyotes probably have some influence on deer populations through capturing fawns. (They may have more as, in the absence of the wolf, some populations evolve into a larger animal, better able to deal with larger prey.) Coyotes also eat chipmunks and white footed mice, a carrier of Lyme disease.
All this brings us to the suburbs, the modern barnyard, where dogs, cats and cars replace cattle, pigs and chickens: the home of modern people.
In dry climate suburbs are oases of damp. Screech owls are more abundant in Texas suburbs with their sprinkled lawns, and abundant insect life (a major part of the owl’s diet), than out in the dry countryside. (How long the sprinkling will last is another matter.) Many people feed songbirds, attracting at the same time raccoons, Norway rats, skunks, coyotes, crows, bears, red squirrels, chipmunks, white footed mice and other animals, whose presence they often come to regard as a problem. So suburban homes are equipped with pellet guns.
There are two problems. The first is deciding which animals we want to live with; the second is managing the habitat so as to provide a more complete compliment of species and so help control animals like crows, jays, opossums, English sparrows, feral cats and perhaps infections like Lyme disease. (The more species for the Ixodes ticks to bite, the less their level of infection—most animals are not competent carriers of the disease.)
Large undeveloped areas help. Not building the suburb but rebuilding the city to be more livable with trees, parks and public transportation, and still holding more people, helps the most. Deer may retreat to the wooded parts of cemeteries or golf courses during the day. Foxes, skunks and raccoons will make do with little cover, living under porches and becoming mostly nocturnal. More bears in Nevada live in Las Vegas than in the countryside. The city bears grow larger and have more young (on abundant dumpster food); but die more frequently in automobile accidents.
Keeping bears out of Las Vegas thus means bear proof dumpsters, and probably hunting; while keeping mountain lions out of western suburbs means keeping out deer, and probably shooting lions.
But we can deal with coyotes, as we do with (much more dangerous) pet dogs. Thus the undeveloped areas in the suburbs, ideally near watercourses. Coyotes need a retreat, as do great horned owls, barred owls and goshawks. Goshawks prefer a substantial tree (though not as substantial as those favored by the long winged ospreys and eagles), owls like dense cover for resting and nesting (a clump of hemlocks in a larger wood). Some owls will use nest boxes and, like bluebirds or wood ducks, their number can probably be increased this way, with salutary effects on populations of small rodents (like white footed mice).
Resident Canada geese can be controlled partly by manipulating their landscape: letting the grass grow. Geese will avoid tall grass or other cover in which coyotes can hide, while large areas of freshly mowed grass are ideal for them: long vistas; and a new meal, every day. Actually the cycle of grass, goose poop, grass is a virtuous circle which intelligent landscape managers could use (and thus save their fertilizer expenses) by devising a machine to pick up the poop to pile and compost (or pulverize and scatter). Clever construction of golf courses or playing fields would help keep geese away from people and their sandals. Some tolerance is necessary in any situation with animals, as is some predation on the geese, young or old, by humans, egg eating foxes, neck snapping coyotes, owls, goshawks and eagles.
So I imagine suburbs as fingers of settlement in larger swaths of desert, prairie or forest; the people generally on higher ground, away from water, near the breezes. Trees shade suburban roads, deciduous trees shade the south side of houses, clumps of evergreens block northwest winds. Banks of solar collectors shade roofs, laundry decorates the yards. Water drains in open ditches with cattails, frogs, nesting wrens, and probably a few mosquitoes. Such drains also absorb runoff from streets and parking lots (some also covered with solar collectors). The open land near the houses has playing fields and places for dogs to run, while the land further away (or near damper habitat) is left alone, with a few trails for birdwatchers or budding naturalists. Dead trees in the woods are left standing. Fallen trees are left on the ground. Larger streams run through the suburbs as corridors of native habitat, thus further filtering (along with the open vegetated drains) the runoff water that reaches them. Ideally, the sewage effluent from the town, purged of toxins (or free of them, since none go down the drain) only add sufficient nutrients to the water to improve the fishery (as that notable one for brown trout in the Bow River that runs through Calgary, Alberta; the brown trout is not native to the Bow and is out competing the native cutthroat trout—the same story as with browns and brook trout in the East—but nothing’s perfect). This is a matter of the volume of nutrients and of the stream.
Of course most of the nutrients in the sewage belong back on nearby farmland, with which, like the urban center, the suburb is allied.
In an earlier Comic I mentioned the local cowbirds terrorized by sharpshinned hawks and merlins. The cowbirds lay their eggs in the nests of other birds and let them raise their young; the growing cowbirds push the competing young out of the nest. Over the last century cowbirds have spread from the plains and prairies east into the artificial human prairie that has replaced the eastern forest in North America and (along with midsized predators like raccoons, opossums, house cats and skunks) have helped reduce songbirds populations by 50% or more (habitat change and industrial pollution also helped). When I moved to the Adirondacks in 1972 the spring sighting of a male cowbird gurgling from the top of our bare apple tree, the glossy black singer perched above his two dove gray companions, made me smile. The cowbird was a common bird in central New York, where I grew up, but (like the raven or the turkey vulture) uncommon in the Adirondacks in the 1950s.
While doing his laundry in a nearby village a friend watched a merlin (a fierce little falcon the size of a robin) harassing the starlings that nested in the eves of the laundromat. Merlins were extremely uncommon 40-50 years ago but over the last decade have been on a roll.
Until fairly recently it was legal to shoot hawks (many of them ate domestic chickens and ducks) and in the early twentieth century thousands were shot each fall as they slid south on air currents above Appalachian ridges, or cruised along Atlantic beaches. Walkers in the woods shot them. Pennsylvania had a $5 bounty on goshawks in the 1930s (not a small sum at the time) when Hawk Mountain Sanctuary was established. Bird books from the early twentieth century debated which raptors should be eliminated: usually the verdict fell on the bird killers, the three short winged hunters of the forest, the sharpshin, the Cooper’s hawk, the goshawk, birds of similar form and abilities in different sizes. The merlin’s rarity made it unimportant. The writers of the books were ornithologists (they favored more songbirds). The story is the same as for mountain lions and wolves (to which many hawks were compared): shot to save the deer.
These books have tales from when hawks were more abundant. Goshawks, the largest of the accepters (and thus the least common, but commonly seen) would strike a rabbit or a hen with such force that the animal’s side would be torn off. When shot at while striking a hen, a goshawk would attack the man with the gun. In thick cover they would bound under trees after rabbits they had missed. Anything that flew or ran was fair game. One battle between a goshawk and a barred owl ended with both birds dead, the owl bleeding to death, the goshawk beheaded.
Large hunters are used to getting their way. They don’t like to be told what to do. Their fierceness helps them survive.
Hawks also suffered from eggshell thinning during the age of DDT (1945-1972 in the United States; approximately the economic life of the manufacturing facility). DDT interfered with calcium metabolism in birds; the result was eggshells that broke under the weight of a brooding bird. Not only hawks suffered, smaller birds did also, but being at the top of long food chains that accumulated the chemical, hawks suffered the most. Peregrine falcons more or less disappeared from Great Britain and the eastern United States. Goshawks, which eat gamebirds and small mammals, which eat leaves, berries and grass (thus situated at the end of shorter foodchains), suffered less.
Lately other chemicals, including other industrial chlorinated hydrocarbons that act as hormone mimics, like DDT, and heavy metals like mercury, a neurotoxin released by burning coal, have become problems for some birds (gulls, cormorants, thrushes); but some raptors seem to be increasing.
Not only hawks were more abundant. Flocks of black billed cuckoos followed infestations of tent caterpillars and would clear small orchards of their nests in a day. One of the common names for the rose breasted grosbeak was potato bug bird; but I have never seen grosbeaks eating potato bugs (or in numbers that could eat enough to help). Cuckoos are now rather uncommon and the silken nests of tent caterpillars on roadside trees (most birds won’t eat the hairy adults) go unmolested.
Such stories make one suspect that populations of North American breeding birds are really down 90-95% from the time of European settlement.
Conservationists who want to restore large animals speak of the three Cs: cores, corridors, carnivores. Cores are ecosystems restored as much as possible to their wild state (thus without people in the developed world). Corridors connect cores, turning separate populations of plants and animals into metapopulations. Carnivores influence the growth of plants and the abundance and types of animals and so are necessary for the health of cores.
This influence of carnivores happens on all size levels, from microbes to moose. Large carnivores influence forest succession by eating large herbivores like deer and moose, which through their feeding habits influence forest succession and the plants of the forest floor. Large carnivores also eat midsized carnivores (their competition; or a tasty snack) and so influence songbird numbers. (Many so called mid size predators are nest predators of songbirds.)
The same is true in birds. Large raptors like goshawks eat crows (a nest robber, also on the increase since shooting of crows has been regulated) as well as rabbits and squirrels. Some great horned owls specialize in crows, which roost communally. Thus one sees flocks of crows roosting at night in the bright lights near malls or superhighways. Smaller raptors eat jays (another nest predator) as well birds the size of starlings and waxwings and also smaller ones like indigo buntings, house wrens and English sparrows.
North Americans are unlikely to live with mountain lions or wolves, despite the fact that deer, which are involved in 1.5 million car accidents yearly in North America, kill many more people than either. (Mountain lions will stalk and kill people but wolves, at least in North America, avoid them.) From a purely utilitarian point of view, we would be better off if mountain lions were abundant enough to control deer numbers and so reduce the number of people killed in collisions with deer (about 225 annually), even if the lions killed 10-20 people a year.
But the emotional difference between dying from a collision with a long legged herbivore that dashes into the road and from being stalked by a large cat that pounces on you from behind, breaks your neck, opens your chest and eats your heart and lungs, is of course considerable.
North Americans may manage to live with coyotes (many millions of Los Angelenos already do), which kill feral (and pet) cats, a major predator of songbirds (and keep many house cats, terrified, indoors). Coyotes have a major influence on songbird populations in Californian canyons: where there are coyotes there are songbirds, where not, not. Coyotes probably have some influence on deer populations through capturing fawns. (They may have more as, in the absence of the wolf, some populations evolve into a larger animal, better able to deal with larger prey.) Coyotes also eat chipmunks and white footed mice, a carrier of Lyme disease.
All this brings us to the suburbs, the modern barnyard, where dogs, cats and cars replace cattle, pigs and chickens: the home of modern people.
In dry climate suburbs are oases of damp. Screech owls are more abundant in Texas suburbs with their sprinkled lawns, and abundant insect life (a major part of the owl’s diet), than out in the dry countryside. (How long the sprinkling will last is another matter.) Many people feed songbirds, attracting at the same time raccoons, Norway rats, skunks, coyotes, crows, bears, red squirrels, chipmunks, white footed mice and other animals, whose presence they often come to regard as a problem. So suburban homes are equipped with pellet guns.
There are two problems. The first is deciding which animals we want to live with; the second is managing the habitat so as to provide a more complete compliment of species and so help control animals like crows, jays, opossums, English sparrows, feral cats and perhaps infections like Lyme disease. (The more species for the Ixodes ticks to bite, the less their level of infection—most animals are not competent carriers of the disease.)
Large undeveloped areas help. Not building the suburb but rebuilding the city to be more livable with trees, parks and public transportation, and still holding more people, helps the most. Deer may retreat to the wooded parts of cemeteries or golf courses during the day. Foxes, skunks and raccoons will make do with little cover, living under porches and becoming mostly nocturnal. More bears in Nevada live in Las Vegas than in the countryside. The city bears grow larger and have more young (on abundant dumpster food); but die more frequently in automobile accidents.
Keeping bears out of Las Vegas thus means bear proof dumpsters, and probably hunting; while keeping mountain lions out of western suburbs means keeping out deer, and probably shooting lions.
But we can deal with coyotes, as we do with (much more dangerous) pet dogs. Thus the undeveloped areas in the suburbs, ideally near watercourses. Coyotes need a retreat, as do great horned owls, barred owls and goshawks. Goshawks prefer a substantial tree (though not as substantial as those favored by the long winged ospreys and eagles), owls like dense cover for resting and nesting (a clump of hemlocks in a larger wood). Some owls will use nest boxes and, like bluebirds or wood ducks, their number can probably be increased this way, with salutary effects on populations of small rodents (like white footed mice).
Resident Canada geese can be controlled partly by manipulating their landscape: letting the grass grow. Geese will avoid tall grass or other cover in which coyotes can hide, while large areas of freshly mowed grass are ideal for them: long vistas; and a new meal, every day. Actually the cycle of grass, goose poop, grass is a virtuous circle which intelligent landscape managers could use (and thus save their fertilizer expenses) by devising a machine to pick up the poop to pile and compost (or pulverize and scatter). Clever construction of golf courses or playing fields would help keep geese away from people and their sandals. Some tolerance is necessary in any situation with animals, as is some predation on the geese, young or old, by humans, egg eating foxes, neck snapping coyotes, owls, goshawks and eagles.
So I imagine suburbs as fingers of settlement in larger swaths of desert, prairie or forest; the people generally on higher ground, away from water, near the breezes. Trees shade suburban roads, deciduous trees shade the south side of houses, clumps of evergreens block northwest winds. Banks of solar collectors shade roofs, laundry decorates the yards. Water drains in open ditches with cattails, frogs, nesting wrens, and probably a few mosquitoes. Such drains also absorb runoff from streets and parking lots (some also covered with solar collectors). The open land near the houses has playing fields and places for dogs to run, while the land further away (or near damper habitat) is left alone, with a few trails for birdwatchers or budding naturalists. Dead trees in the woods are left standing. Fallen trees are left on the ground. Larger streams run through the suburbs as corridors of native habitat, thus further filtering (along with the open vegetated drains) the runoff water that reaches them. Ideally, the sewage effluent from the town, purged of toxins (or free of them, since none go down the drain) only add sufficient nutrients to the water to improve the fishery (as that notable one for brown trout in the Bow River that runs through Calgary, Alberta; the brown trout is not native to the Bow and is out competing the native cutthroat trout—the same story as with browns and brook trout in the East—but nothing’s perfect). This is a matter of the volume of nutrients and of the stream.
Of course most of the nutrients in the sewage belong back on nearby farmland, with which, like the urban center, the suburb is allied.
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