|
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. [1] 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. [2] 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.
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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. [3] 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
Botany
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. [4] 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.
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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. [5] 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. [6] 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." [7]
"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. [8]
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. [9] 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. [10] 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. [11]
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. [12] 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). [13]
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?
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References
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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