Keystones and Cops: An Eco-Mystery Thriller
by Peter Bane
If you'd just witnessed the crime of the century and you thought you knew the culprit and the story, wouldn't you be eager to tell it? No, I don't mean Dubya and the Twin Towers - that one's already been figured out, but another story, from another century, copiously reported but equally misunderstood.
Ninety-nine years ago, also in New York, officials identified a sinister Asian invader as the cause of what would become the catastrophe of modern North American history. Livelihoods would be devastated, vast tracts of the country depopulated, violence and crime would explode in the wake of the disaster; whole communities were dragged into drug trafficking. Slow at first to react, the nation soon grasped the full implications of the tragedy. A crash program to defend the homeland was launched with support of the government in Washington. Restrictions on transit were imposed. Chemical warfare was initiated. A scorched earth policy was attempted but ultimately failed because the enemy was too wily. Escaping from the government legions sent to hunt it down and contain its villainy, the menace reproduced invisibly and spread rapidly throughout the population, wreaking havoc with the economy.
For a more innocent and optimistic America, Cryphonectria parasitica was the Osama bin Laden of its day. A cruel and ruthless murderer, it would ultimately slay one in every four American...
...trees. Chestnuts: the dominant tree of the Eastern forests. Four billion in number, ranging from Maine to Mississippi with outliers in the Midwest, they comprised 25-40% of the mixed deciduous hardwoods. Called "Redwoods of the East" because of their towering height and immense girth (some reached 20 feet in diameter, over 100 feet in both height and spread), the trees formed the backbone of the rural economy over the full length of the Appalachian Mountains and foothills. Valued for their straight-grained, lightweight, and rot-resistant timber; the tannins from their bark and wood; and for their tremendous crops of sweet, delicious, nuts avidly eaten by humans and wildlife alike; the Chestnut was without peers in the vegetable kingdom. Today, all that remain are millions of shrubby stump sprouts (some trees not killed entirely have put up new shoots, but these succumb to the disease after a few years), a handful of erratics in unique situations, and a small number of declining groves in Wisconsin and Michigan that were late to be infected: Victims of the blight, every one.
Every school child in America hears this story sooner or later. It's been repeated in thousands of publications. It's old news, a tragedy long past, if not forgotten: perhaps an early harbinger of America's fall from grace. For the record there are new and promising developments, too. Chestnut enthusiasts began breeding blight resistance (from Asian chestnuts, the presumed agents of infection) into American chestnuts in the late 1970's and expect to have a quantity of blight-resistant seeds and trees for planting out by 2005 or 2006.  Other groups have been working to diminish the virulence of the pathogen by inoculating infected trees with another fungal agent from Europe that renders chestnut blight much less harmful, thus allowing the tree to survive and reproduce, a process known as hypervirulence.  There have even been attempts to bioengineer the disease to limit its destructiveness. These are worthy efforts and the individuals involved are dedicated visionaries, but let's step back for a moment from the drama of loss and recovery to examine what may have been behind this shocking set of events.
Understanding the Terrain
To develop a full sense of the crime that happened to the American chestnut (Castanea dentata), we have to understand its life cycle and evolutionary history, its botany, and its role in the vast biome for botany, and its role in the vast biome for which it had become emblematic. We also need to look at the chronology of its demise to learn what we can about the roots of this epidemic. The pathways of our investigation may take us in some unexpected directions.
When the chestnut blight (Cryphonectria parasitica, sometimes called Endothia parasitica) was first identified on American chestnut in 1904 at the New York Zoological Garden, it's likely that the disease had already been at work for as much as a generation. This is inferred because the spread of the disease was very rapid after 1904.
The first Japanese chestnuts were imported to the United States in 1876 for the nursery trade. Japanese chestnuts (C. crenata), which have very large nuts, are the most blight resistant of the main chestnut species. Their Chinese cousins (C. mollissima) share some of this resistance. The European species (C. sativa) was susceptible, and was infected by the blight in the 1950's after its American cousins had already collapsed, but surprisingly, a hypovirulent (less potent) strain of the fungus appeared in Italy and spread through European groves. After about 15 years of infection the European chestnuts seemed to have recovered; they continue to bear commercial crops.
Not so lucky the American chestnut. Soon after the blight was discovered in the Bronx, infected trees were found in southern New England and New Jersey. The blight began its slow, deadly march south along the Appalachian chain.
A Tree Nonpareil
Chestnuts were more than an important tree in Appalachia - they had been the ridgepole of the economy. Chestnut lumber was far and away the greatest part of the economic value of the hardwood forest. It was used for everything from barns to caskets. The trees provided the nations's main source of tannin for leather processing. Animals, including large herds of domestic hogs, fattened on the nuts, and perhaps most socially significant, the chestnut provided a ready cash income to millions of rural dwellers. In an era when the daily wage averaged $1.75, chestnuts sold for ten cents a pound. A man working the harvest could easily gather 100 pounds in a day, and could put by a year's savings from a few weeks work.  The subsequent loss of the chestnut, simultaneous in most places with Prohibition, drove rural mountain dwellers to "moonshining," converting their corn into mash and thence to bootleg whiskey, as the only way to derive a cash income from the land and to pay the taxes. Later tobacco would join alcohol as a principal replacement for the chestnut in the region's cash economy.
About 1911, as it became obvious that a catastrophe was in the making, the federal government began funding efforts to avert the impending disaster. Plant quarantine legislation was passed in 1912. Fungicides were tried unsuccessfully. Chemical treatment proved ineffective. Attempts were made to cut a wide "firebreak" barrier to prevent the advance of the disease, but the blight jumped past it, spreading as much as 50 miles a year. By 1938, most of the chestnuts were dead.
In the early years of the 20th century, scientific forestry was in its infancy. Evolutionary biology was still a relatively new science, and ecology was scarcely known. Although the chestnut emergency stimulated scientific research into the etiology of the fungal disease, and breeding work based on this research appears promising, a holistic view of the phenomenon has yet to emerge. A crisis and bottom-up action appears, through these same tools of analysis, to be random and chaotic. Its true meaning may only be understood by taking a systems approach or top-down view.
Chestnut first appeared in North America about 40 million years ago. It is a member of the beech family, Fagaceae, to which belong also the oaks, all relatively long-lived, crown-bearing nut trees common to the forests of Europe, North America, and east Asia. These trees are all "mast" bearers, that is, they throw large crops of seed every two to three years rather than annually. Their highly nutritious nuts are rich in carbohydrates and less oily that the walnuts and hickories, to which they are more distantly related. The mast provided seasonal food for a huge number of birds and mammals, as well as humans, and the irregular pulsing of the tree's reproductive cycle was an adaptation to this heavy seed predation, a strategy biologists call "satiation." A periodic dearth of mast suppresses populations of the deer, turkey, squirrels, pigeons, and others who prey upon the tree's seeds. This ensures that when abundance returns a year or two later, some of the billions of seeds will survive the (much reduced) onslaught of hungry seed predators.
Anatomy of a Forest Giant
Among the chestnuts, the American produces the smallest but the sweetest nut, a food that was highly prized by native Americans, the European settlers in the region, and by a plethora of wildlife.
Within the 200 million acres of its native range, American chestnut dominated the forest. At the time of its collapse it was at least one in every four trees throughout the eastern U.S. Favoring north- and east-facing cove slopes where it comprised over half of the forest, it often occurred in pure stands. Dominance was supported by it ability to persist shrub-like in the undergrowth for many years (the reason it has not been eliminated biologically from the forest), its habit of rapid growth following disturbance, and by the production of allelopathic chemicals in its leaves and bark. These substances, leachates of which were constantly dripped into the surrounding soils by regular rains, suppressed the seed germination and growth of other trees such as white pine and hemlock which might otherwise have competed successfully for the same niches chestnut favored.  Great height assured its ability to photosynthesize and bear seed, while rot-resistant wood allowed the tree to persist in the constantly moist environments of its native terrain.
The chestnut, unlike its cousins the oaks and beeches, with which it was often associated, is a shallow-rooted tree. It achieved its towering heights and great spreads by the use of lightweight wood and a massive reach of lateral roots. It typically grew on well-drained, sloping soils, in moist microclimates under high rainfall regimes, all factors consistent with its rooting habit.
So, we should ask: How did this tree, which grew so fast and bore copious crops of nutrient-rich seeds, feed itself?
Like other deciduous species in the Eastern North American forest, chestnut dropped its leaves each autumn to blanket the soils at its roots, and these droppings over millennia built up deep humus-rich soils which, like a battery, were able to hold the vast quantities of nutrient needed to feed the trees. But what charged the battery? Soils in the southern Appalachians (where the chestnuts reached their greatest glory), despite present forest cover, are heavily leached and nutrient-poor. The trees still drop their leaves, but the soil battery has been run down. Some of this, to be sure, is a historic consequence: logging throughout the Appalachians was ruthless and soil erosion losses were immense. But we have to see past this. Chestnuts grew on slopes where soils were always thinner and less fertile than in the bottomlands. Rainfall of 50-60 inches per year promotes soil acidity which in turn ties up some minerals, and together with warm summer temperatures stimulates rapid leaching of the rest. Are we facing a paradox?
The heaviest logging and the most destructive erosion occurred after the chestnut blight began to spread, in the 1920's. In part this was an effect of the blight, which encouraged landowners to cut chestnuts for their wood before, or shortly after infection. With one of every four trees removed from the forest, some in pure stands, a shock wave rolled over the mountains. In the wake of this logging and with the loss of the chestnut gutting the local cash economy, massive depopulation took place throughout rural Appalachia.
Our question remains, however, what was at the root of this collapse, the end phases of which were so grim? Human activity without a doubt: The chestnuts fell victim to foreign imports. They were an early casualty of global trade: a host of helpful, noble, innocent natives felled by a dastardly foreign villain. That story played well to a society grappling with endemic racism, but it's rather too simple. Something is missing.
Let's consider the heroic success of the chestnut.
The Chestnut Ascendancy
Following the last glaciation and southward retreat of the hardwood forests, the chestnut began to spread out of the southern Appalachian coves where it had taken refuge, back into the Ohio Valley and New England. Pollen records indicate that it reached Connecticut and Massachusetts in large numbers about 2500 years ago.  A parallel but even more pronounced spike in New England chestnut populations appears to have followed on the arrival of Europeans in the area some four hundred years ago, suggesting that disturbance favors its spread.
We appear to be dealing with an opportunistic and aggressive tribal tree species that was at the same time long-lived and dependent on relatively high levels of available soil nutrient. It both suppressed unrelated competitors in its own niche by the use of allelopathic chemicals, and outstripped the growth of those close relatives, oak and beech, which could tolerate its chemical effusions. What sustained it?
Plants that produce fruits are always interested in attracting bird or other animal seed dispersers as part of their reproductive strategies. The energetic investment in fruit is paid back by the manifold opportunities to reach distant niches with one's offspring delivered in a high-nutrient packet of fertilizer. But chestnut seems not to have adopted this evolutionary approach; rather it depended on the scatterbrained habit of squirrels to plant its seeds nearby and forget where most of them went! Since the tree was tolerant of understory conditions and content to live in pure stands, distant spread of its progeny apparently wasn't needed, while the advantages of growth close by the protective boughs and chemistry of the tribe were considerable.
Most of the animals that fed on chestnuts were seed predators: deer, turkey, and the now extinct passenger pigeon. While deer populations at upwards of 10 million may now exceed historic levels (because of the increase of patchiness in the landscape and the absence of large predators), and turkey numbers are recovering from a low of 30,000 a century ago to nearly a million and a half today, in sheer numbers, in total biomass, and in the rapidity of cycling of food resources, these surviving creatures were completely dwarfed by the passenger pigeon. It is to the saga of the pigeon's glory and final days that we must turn for clues to the nutrient base of the chestnut.
A Bird Made for Flight
There was never a sight in all the world we humans have known to match the splendor of the passenger pigeon in its flights. Vivid in their red, gold, and purple plumage, with long tails and streamlined bodies, they were grace incarnate as they sped by overhead in veritable torrents of birds, wheeling and turing, rising and diving with a thunderous flapping of their wings, as if the whole were an avian embodiment of the aurora borealis. Perhaps the great herds of wildlife moving over the Serengeti may inspire a similar feeling of awe.
Numbering, like the chestnut, about four billion individuals in the early 19th century, the passenger pigeon may have been the most successful social bird ever to have lived. Completely dominating the skies within its range, it may have been as much as 40% of the bird population of the continent, the most numerous higher animal species on earth at the time.  Intensely gregarious, it massed in numbers beyond comprehension. J.J. Audubon describes a flock that passed him over Kentucky. He began tallying groups as they passed overhead but soon gave up as the sky was darkened with their vast number for more than three days. Hundreds of millions of birds in each mass may have flown together. The largest roosting of passenger pigeons ever recorded was seen in Wisconsin in 1871: it spread over 850 square miles, and was estimate at 136 million, over 250 birds per acre. This, however, was after their numbers had already begun to decline significantly.
The pigeons were adapted to prime functions: they fed voraciously and systematically, and they flew like mad. Having effectively escaped the limits of predation, they drew strength in sheer numbers and great speed, overwhelming the ability of any predators (save ultimately humans) to seriously dent the size of the colony. Audubon again reports that birds taken in New York had undigested grains of rice in their crops, seed that could only have been eaten fresh from the fields in South Carolina or Georgia. Since the power of the bird's digestion is great and complete passage of food takes no more than 12 hours, he concluded that they must have exceeded a sustained speed of 60 miles per hour in their marathon flights.
With keen eyesight they could survey the countryside at high speed to assess the availability of large food resources. After locating a sufficiently rich country the colony would roost in dense forest, settling into the upper branches at such densities that large limbs regularly fell crashing through the masses of birds perched below, and "many trees two feet in diameter, I observed, were broken off at no great distance above the ground..."wrote the master artist and naturalist. On their departure the roosting areas would resemble "very much a section of country over which has passed a violent hurricane," noted Col. David Crockett in 1835.
Once roosted, the colony would range, en masse, up to 200 miles a day in search of food, returning at night to the woods. They ate like the whirlwind, observers commenting on the rolling wheel of birds that would move through an area. The colony would land and the lead birds would move systematically through the fields or wood, eating seeds, nuts, berries, earthworms, grasshoppers, and even burrowing with their beaks for tubers and legume nodules. As the front exhausted an area, birds in the rear would rise up, swoop over the flock, and settling to earth just ahead of the colony's advance, take their place on the feeding line. This continued patiently throughout the day or until predators menaced, then the whole mass would take wing and speed off to another area. They continued harvesting until the resources of the whole region were depleted; then they would depart to find the next landscape of surplus. In their migrations they never took the same path twice, but always sought territories rich with food.
Undaunted by cold (they ranged north to Hudson's Bay and to the south end of Lake Winnipeg, 58 degrees and 62 degrees N. latitude respectively), they were recorded moving north in early March while temperatures hovered at -20 degrees F. Winters were spent in the upland of Louisiana, Mississippi, Alabama, Georgia, and the Carolinas. They reached the Atlantic only sporadically, but inhabited both flanks of the Appalachians and ranged west of the Mississippi River and south to the Texas Hill country.
Long-lived (the last passenger pigeon died in captivity at 29 years of age), the birds bred in affectionate, talkative pairs, nested clumsily, and raised one or two squabs per nesting, most typically one male, the other female. The nests, made hastily of coarse twigs, were so poorly constructed that often one of the two eggs laid or the two squabs hatched would fall to the ground inadvertently, there to make a meal for some eager animal. The breeding cycle took a little less than a month and was repeated several times each season. Audubon estimates their increase to be two to four times their number per year. Since the population had probably peaked near the capacity of the subcontinent to support their profligacy, it can be imagined that several billion passenger year (at 10-12 oz / 280-335g each, some 10 to the 9th power kilograms of protein) were consumed by various organisms, and that they converted an immense amount of vegetable and insect matter into meat and dung.
"...and their dung would fall like hail." 
"The dung fell in spots not unlike melting flakes of snow."
"The dung lay several inches deep covering the whole extent of the roosting places."
They favored beechnuts, chestnuts, and oaks, eating so avidly that on swallowing a particularly large acorn, a bird might be seen to gasp for some time as if choking. Undoubtedly they preferred the smaller beech and chestnut mast for its ease of consumption. They harvested not only fallen nuts but those still on the tree, having perfected a method of grasping the nuts in the husks and flapping their wings backwards to extract the kernels.
What the observers imply, but do not record, is the action of the birds in concentrating nutrients from the surrounding territories onto the soils of the larger forest tracts. For the birds always sought out large unbroken woodlands for their roosts (so much so that late 19th-century deforestation together with commercial hunting almost ensured the pigeons' doom). No more perfect description of a nutrient pump ideally matched to the demands of the shallow-rooted deep-forest dominating chestnut could be conceived. The birds, which began their nesting in mid-May, would lay down a thick mat of mineral-rich manure just ahead of the chestnut's June-July bloom, a delivery of trace elements well-timed to support the chestnut's profuse flowering, its white blossoms giving the mountains the appearance of freshly fallen snow at mid-summer.
In addition, the devastation wrought by the pigeons' roosting would have been an advantage for young chestnuts growing understory, opening holes in the canopy that probably allowed the trees to consolidate their hold on an area.
But the flocks Audubon had observed in the 1830's began to diminish after the Civil War. By the 1870's clearing of forests for farmland accelerated their decline as the telegraph and railroad networks allowed commercial hunters at last to compete with the birds' prodigious speed. Markets in teeming eastern cities made wholesale slaughter financially attractive and literally trainloads of pigeons were shipped to the cities. Huge volumes were fed to hogs. Michigan recorded its last large nesting in 1878, Oklahoma and Pennsylvania in 1886. By 1890 the passenger pigeon was functionally extinct, though isolated birds were still seen in the wild for another ten years. The last wild pigeon was shot about 1900. 
Though they had bred successfully in captivity since the 1870's, efforts to raise the pigeons artificially failed when they disappeared from the wild. The first phase of the crime was complete. "Martha," the last captive pigeon in the Cincinnati Zoo, took with her to eternity the heartbeat of this remarkable race on September 1st, 1914.
The thesis that these two great American extinctions may be causally linked appears to have received little attention. Popular historians and ecologists of every stripe list them in virtually the same breath as landmark, human-generated events, yet the ornithologists seem to not be communicating with the forest biologists. Ecologists might seem a likely group to have given this notion a passing glance. Surely a few have at least entertained the thought.
A Possible Test
This hypothesis, which, absent one of its main components, is not susceptible to ironclad proof, could nevertheless be tested by exploring in greater detail than has been done heretofore, the link between mineral availability and blight infection in chestnut. My brief researches turned up some references to present-day blight-free (though stunted) populations of chestnut in association with mineral tailings from a zinc mine in Pennsylvania. If zinc tailings (containing who knows what, at undoubtedly hideous levels of acidity) can keep chestnut blight-free, what about two or three inches a year of bird manure?
Forest clearance has been widely understood as contributing to the demise of the pigeon, but the bird's pre-eminence - let me now call it a keystone species - in cycling nutrients over the eastern half of the continent cannot be underestimated. Writers have noted, in the context of pigeon extinction, the "inexplicable" shrinkage of the beech forests since early colonial times, but have made little of it. I posit that the chestnuts (which did indeed succumb to the blight organism, truly imported from the Orient)were rendered dramatically more susceptible than they might otherwise have been by the choking off of a main nutrient flow in the generation immediately preceding 1904. Indeed, the blight, probably present from the 1870's onward, may have been kept in check by the residual effects of the great nutrient pump. I suspect that European chestnuts weathered the attack of the blight and survived because of agricultureal cycling of nutrients in the orchards by the sue of swine, a creature whose manure is even higher in zinc than that of poultry. We must ask ourselves: Might not more of the American chestnuts have survived had the pigeons still been roosting in them, and had the trees not been mowed down in a kind of "salvage-logging" hysteria, which surely eliminated any evidence of native genetic resistance? These surface-feeding trees required a powerful replenishment of mineral nutrient for their steady production of mast and their rapid growth. In the high-rainfall environments of their native range, soils are readily leached of these nutrients unless continuously "topped up". The balance is a delicate one.
A Modern Parallel
Though no one cognizant of modern ecological theory was able to record the interactions of pigeons with chestnut trees, I have personally observed parallels with other surface-feeding nut trees.
Macadamia nuts were established in Hawaii from about 1964 to diversify an agriculture heavily dependent on sugarcane. These large nut plantations, managed by the Big Five sugar companies throughout the islands, were treated to the full range of conventional agro-technology: chemicals and mechanical harvesting. By the early nineties a mysterious fungal organism had appeared which caused many macadamia trees to die suddenly, within 90 days of infection. I witnessed in one orchard the harvesting of nuts by mechanical vacuum acton that sucked everything of the orchard floor up to and including stones the size of golf balls. Simultaneous with the pillage, a scientist on the other side of the orchard was explaining earnestly to a group of tourist about the grim fate of trees growing sick with this mystery fungus. Since the macadamia is a surface-feeding rain forest species, it should have been no surprise that 30 years of abuse to the roots of these trees, even on rich volcanic soils, would result in nutrient depletion, and weakening, for which the mystery fungus was only the cleanup crew.
Restoration of the chestnut proceeds and I await it as eagerly as any, but the eventual re-establishment of chestnut groves would be greatly supported by the incorporation of an element of rapid nutrient cycling such as the pigeons once supplied.
Our confounding by the germ theory of disease and a century of phony medicine has crippled our civilization's ability to understand biological phenomena holistically, especially in the arena of death.  The same focus on actors and objects rather than processes and energies has crippled our political understanding as well. But let me conclude with a brief consideration of the concept of key species.
A Keystone of the Continent's Arch
I believe that the passenger pigeon was a key nutrient cycler that maintained forest health on a sub-continental scale throughout the eastern forest biome. By the nature of its scale it could have but few parallels. Two others that come to mind immediately are the bison, which numbering in excess of 50 millions maintained the tall-and short-grass prairies over a million square miles of the mid-continent - and which were also ecologically extinguished in the late 19th century; and secondly, the salmon, whose final days we may be tragically fated to mark soon. These anadromous (ocean-living, river-spawning) fish translocated huge quantities of marine minerals and protein to the headwaters of western rivers where they form a key link in the food web, supplying, with the help of top carnivore bear and birds of prey, phosphorus, calcium, and trace minerals of inestimable value to inland ecosystems.  These minerals moved not in the salmon's feces, as did the nutrients harvested by the bison and the passenger pigeon, but as their bodies, which are sacrificed annually by the millions of pounds.
Of course the bison and the pigeon all fed large numbers of carnivores and small consumers. Nutrient flows from the pigeon may have reached 10 billion kilograms / year or more (concentrated on the forests); from the bison herds, two or three times as much, though more uniformly spread across the grasslands. In aggregate these volumes approach the scale of modern commercial fertilizer use (much of which is wasted anyway). Salon harvest (over a smaller though still significant territory) may have reached approximately 500 million pounds annually in Washington, Oregon, California and Idaho; we can only guess what prehistoric quantities were involved, to say nothing of the Canadian and Alaskan streams. 
Toby Hemenway has written in the magazine (PcA #48) of the profound role played by beavers in shaping North American river valleys. To encompass the full suite of ecological functions now derelict (not merely species extinct), we must look beyond the beaver, the pigeon, the bison, and the salmon, to see the key role of elephants (gone a mere 10,000 years) in maintaining the nearly vanished American savannas of the southern plains, and of camels (more distantly removed) in cycling nutrient through the deserts of the Southwest.
We are looking out at a landscape bereft of its most dramatic living forces. If we are seriously interested in restoring North American ecosystems, we must at least admit the abundance that once was here and that humans have destroyed, before we can hope to reclaim it. We might also entertain, as ecologist Paul Martin and others have proposed, the return of a few elephants.  It might give the California condor (our top-order avian scavenger, which once ranged to New England) an invitation to move east again.
Ecologists argue over the meaning of the term keystone species. Strict constructionists prefer the definition they attribute to R.T. Paine, a biologist who coined the term in 1966, which insists that keystone species are predators whose selective predation helps to maintain greater diversity at lower trophic levels (that is, among smaller prey organisms).  The other school of thought holds that keystone functions can be played by many actors on the ecological stage: prey species, habitat modifiers, predators, and more. I prefer the latter view, as it invites free play of the imagination; we are in a situation where the scientific method alone will not save us. Great engagement by the public in scientific inquiry is desperately needed.
At the level of events and organisms, ecological systems are inherently chaotic. To understand the dynamics of North American ecosystems we must lift our view. We can't afford to neglect either history or the system's fundamental organizing processes. Upstream, upwind, and antecedent factors are frequently decisive. Where once the surplus energies of the continent were channeled through animal bodies, great storages that have been squandered, today they are harnessed to human constructs, the greatest of which are our cities. And just as we have seen the collapse of the largest-order populations of the crucial birds, ruminants, trees, and fish due to sporadic action based on the bottom-up fragmented, or strictly social thinking, we are likely seeing the incipient collapse of our largest-order settlements from the same kinds of action; this time I fear, from a very different kind of thinking. [14, 15]
Camels, elephants, pigeons, bison, and salmon. These are the keystones. Now, where are the cops?
1. American Chestnut Foundation. www.acf.org
2. American Chestnut Cooperators Foundation. www.accf-online.org
3. Judy C. Treadwell, Mar. 1996 NC Natural
4. D.B. Vandermasta, D.H. Van Lear, B.D. Clinton. "American chestnut as an allelopath in southern Appalachians", in Forest Ecology and Management (2002) pp. 165, 173-181. www.elesvier.com/locate/foreco.
5. F.L. Paillet. "Chestnut: history & ecology of a transformed species: in Journal of Biogeography, 29, 1517-1530
6. Chipper Woods Bird Observatory. www.cwbo.org.
7. Illinois Natural History Survey Reports, May-June '98. www.inhs.uiuc.edu
8. David E. Blockstein, "Passenger Pigeons, Lyme Disease, and Us: the unintended consequences of the death of a species." www.ncseonline.org/Directory/Staff/DBlockstein/birding_Aug_01.pdf
9. Adeha Feustel, "Bacteria: Pathogens or Agents of Decay," in Permaculture Activist 45, Feb. 2000 10. Associated Press, "Salmon are Natural Recyclers." March, 2000
11. Brock Dolman, personal communication, October, 2000
12. Connie Barlow, Ghosts of Evolution. 2000
13. R.D.Davic, 2000. "Ecological dominants vs. keystone species: A call for reason." Conservation Ecology 4(1): r2. www.consecol.org/vol4/iss1/resp2 14.David Holmgren, Permaculture: Principles and Pathways Beyond Sustainability. 2002
15. Mike Davis, Dead Cities. 2001
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