Voles are adorable and horrifying creatures. When I forget
them, it’s tempting to think that the ecosystem is mostly about plants. But
when chocolate-brown meadow voles are eating every rare gentian every year, I’m
forced to remember that ecosystems are equally animal.
There’s a comparison with you and me. Our bodies are
ecosystems that include more bacterial cells than human cells. As microbes are to us - voles, insects, etc. are to
the prairie. Venerable ecologist E.O. Wilson called them “the little things
that run the world.” (In case you like numbers, each of our human bodies
supports one hundred trillion bacteria, molds and other micro biota, most of
which help us more than they hurt.)
We who seek to save prairies, woodlands and wetlands
once thought that our mission was simply to restore nature, and then nature
would take care of itself. As we explored restoration, successes unfolded like
magic. Hundreds of (until recently) rare plant species eventually found their
niches and became abundant, and the ecosystem grew progressively more diverse and healthy.
Animals (including some endangered ones) also voted their support.
Rare butterflies, snakes and birds increased dramatically. When the first
white-tailed deer returned to the North Branch, we felt we were seeing, in all
our innocence, another confirmation that our prairies and woods were on the
right track. By the time the deer had multiplied out of control and we started
shooting them, conservationists considered them an easily understood exception.
Deer may be nature, but they were wrecking the ecosystem because they lacked predators.
The common meadow vole is promiscuous and barbaric. The similar but
now-rare prairie vole is monogamous and territorial. Is there a clue
hiding in these rodents' morals?
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Then came meadow voles. Why should they get out of balance? Somme
Prairie Grove has a host of vole predators. Red-tailed hawks, great-horned
owls, red foxes, and coyotes all feast so heavily on voles that these little
rodents have been called “the hamburger of the grassland.”
Then rare plants started to vanish. For some species, when
we caged them from the deer, the voles mowed down pretty much every one. Vole numbers follow a “boom and bust” cycle. Could we hope that
their devastations were just temporary? But year after year it was the same
thing, not just in the savanna but in the very high quality and original Somme
Prairie as well. Tom Vanderpoel found the same thing at Grigsby Prairie twenty
miles to the west.
White-footed mice are common at Somme, but we never find them
wiping out a species. Why does this mouse “work well with others” while the voles don’t? |
Are some species populations being lost because of obscure
out-of-balance species? Take the example of the globally-rare eared false foxglove
(Tomanthera auriculata). This plant is an annual. It does not sprout again and get
another chance next year if its reproduction is foiled. A seed bank may keep
producing new plants for some seasons. But sooner or later the last seed will
germinate, and the last plant will enter the bowels of a deer or vole, never to
feel the sun on its chlorophyll again. At Somme, at least in some summers, the
voles eat every foxglove.
We’ve invented “vole exclusion cages” to protect key plants.
But there’s a limit to how many species we can protect that way. Every year, for
example, every uncaged prairie gentian gets cut before the seeds mature.
What could be going wrong? Certain weasels and certain snakes feed
heavily on voles. Those predators are missing at Somme. Should we work to
restore them? That could be a compelling challenge! Are there vole diseases or
insect pests or other controls that have vanished in these small and isolated
sites? Who would study that?
When people, rather than ecosystems, have imbalances, we
call it sickness. The fifth most common reason for people to take antibiotics
is sinus disease. People with sinusitis on average have nine hundred species of
bacteria up their noses. But people with healthy sinuses have more – twelve
hundred species. This is another case where diversity is better than control.
As Dr. Martin Blazer, chairman of the Department of Medicine at NYU said of
human ‘germs,’ “Everyone focuses on the harm. And it’s not that simple, because
without most of these organisms we could never survive.”
In ecosystem restoration we tend to restore one species at a
time, usually by seeds. We could learn something from an earwax story that’s a
favorite of Dr. Andrew Goldberg of U.C.S.F Medical Center. A patient had years
of agony from an infection of his left year. He went through many doctors, who
prescribed a variety of “antibiotics, anti-mold drops – the works.” Except that
nothing did work. Then one day the patient came in smiling and happy. Goldberg assumed he’d tried another
medicine, but no. “I took some wax out of my good ear and put it into my bad
ear, and in a few days I was fine,” the patient told him. This was human
ecosystem restoration.
When we conservationists rescue a rare plant from the
bulldozers at a prairie remnant and move it (and its dirt) to a site under
restoration, we copy Dr. Goldberg’s patient. Tom Vanderpoel wondered how the
rare Mead’s sedge got to the restored-from-scratch Grigsby Prairie. Then he
noticed that each spreading clone of sedge had a hoary puccoon in the middle of
it. Tom had rescued the puccoons from a high-quality remnant that was being
destroyed. Unnoticed, the rare sedge came along for the ride. So, no doubt,
did many species of bacteria, fungi, nematodes, and innumerable others. We
don’t study the results of that sort of thing. We should. Not that it would be easy.
The medical quotes in this post are from Michael Specter’s “Germs
Are Us – Bacteria make us sick. Do they also keep us alive?” in the October 22,
2012 New Yorker. There we learn that a person has about twenty-three thousand
genes. Impressive? Our human
“microbiome” – the bacteria, molds, etc. that live on and in every part of us –
has at least four million genes that help us in countless ways. Our bacteria outdo
us, gene-wise.
Every plant and animal in the wild ecosystem has something
comparable. That means Somme Prairie Grove has a lot of genes. Let’s see: 478
native species times four million genes, give or take a few, yields 1,912,000,000
genes for Somme Prairie Grove.
For every plant species, a natural area is said to have ten animal species.
But then we have to add fungi, bacteria, and God-knows-how-many others.
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Oops, as Ronald Regan would say, there I go again. I forgot
the animals. A “rule of thumb” guesstimates that for every plant species an
ecosystem has about ten animals species (mostly small of course, but yet part
of that petite elite that rules). Thus we compute that a natural area with 478
plant species (and 4,780 animal species) would boast a gene total of a bit over
19 trillion genes. That’s what we save when we’re good stewards. That’s what we
lose if we let bulldozers or “the evil shade of buckthorn” eliminate the
diversity.
Next, I find my perspective flipped by Dr. David Relman,
professor of microbiology and immunology at Stanford. I’ve long claimed that we
need to see ecosystem stewardship as less like physics or chemistry – and more
like human medicine. That is, we have to make many decisions based on best
expert judgment – when we don’t have certain scientific fact. But Relman was
speaking of human health care: “We have to stop looking at medicine as a war
between invading pathogens and our bodies,” he said. “This sort of stewardship
has more in common with park management than it does with our current practice
of trying, in the broadest way possible, to kill microbes.”
Caring for our bodies is like ecosystem management? Well, of
course it is. But here’s the implication for our forests, grasslands and
aquatics: we have to learn as much as we can, make the best use of specialists (both
‘expert’ specialists and ‘local knowledge’ specialists), and then make the best
use of generalists – to decide and act before it’s too late.
Among the Cook County forest preserves, most get no
stewardship help, year after year. In the words of one ecologist, "County-wide (and no doubt region-wide) there
are many good areas of rich diversity whose figurative fingers are sinking
below the waves for the last time."
That’s why many of us find it so rewarding to work (as volunteers
or staff) at this pioneering quest. As one high-schooler said last week at the
Solstice bonfire, “We need people winning Nobel prizes in this stuff.” Yes, we
do. But some of the needed awards would fit better in the Peace Prize category than
in any "hard" science. Conservation needs young new leaders who can span categories
and invent ecosystem futures that work.