| Craig Allen
is trying hard to make ecology relevant.
This effort is not only evident in the many articles he has
written for scientific journals, the many lectures he has
given on forests and fire to a wide variety of audiences,
and in the elegant experiments in ecological restoration he
is conducting, but also in the energy he puts into a conversation
about forests while just hiking to a project site.
Clearly, Allen loves what he does,
And what Allen does is try to understand fundamental ecological
processes in the woodlands and forests of the Jemez Mountains,
west of Santa Fe, N.M. Employed by the US Geological Survey
and stationed at Bandelier National Monument, Allen has devoted
nearly 20 years of his professional life to gaining a comprehensive
understanding of landscape health and sickness, and what constitutes
appropriate cures.
Without management intervention,
But it is not merely an academic interest.
Allen has become a vocal advocate for science-based "adaptive
management" – carefully monitored experimentation
– in our forests. By arguing for science-based decision-making,
however, Allen walks a fine line between the research community,
which is methodical by its nature, and land managers, who
are often under pressure to move quickly. By choice, Allen
has a foot in two worlds that historically have had an uneasy
relationship.
He bridges both worlds for a reason: He believes the deteriorating
conditions of some forests require that relationships between
research and management be improved substantially, and quickly.
Functionality Crisis
Like many ecologists working in the West today, Allen will
tell you that all is not well on the land. Anthropogenic change
over the decades – overgrazing by livestock, fire suppression,
exotic plant species introductions and heavy-handed remediation
strategies – have combined to throw many ecosystems
into a state of poor health. He often cites as "Exhibit
A" the widespread changes in tree-choked Southwestern
ponderosa pine forests that have led to dramatic increases
in stand-replacing "crown" fires in recent years.
But it is not just the West's "working landscapes"
that are in trouble. Allen sees serious damage in much of
what conservationists, and the public, might consider to be
"pristine" landscapes, including the federally designated
wilderness of Bandelier National Monument – which is
news for many.
In a 2001 article for the journal "Wild Earth,"
Allen and two colleagues wrote "Most wilderness areas
in the continental United States are not pristine, and ecosystem
research has shown that conditions in many are deteriorating."
The authors documented that the Bandelier Wilderness is suffering
from "unnatural change," mostly as a result of historic
use of the area that triggered unprecedented change in the
park's ecosystems, resulting in degraded and unsustainable
conditions.
"Similar changes," they write, "have occurred
throughout much of the Southwest."
Specifically, semiarid soils in Bandelier pinyon-juniper woodlands
are "eroding at net rates of about one-half inch per
decade. Given soil depths averaging only one to two feet in
many areas, there will be loss of entire soil bodies across
extensive areas."
This is bad because the rapid loss of topsoil, and the resulting
loss of water available for plants, impedes the growth of
all-important grass cover, thus reducing the incidence of
natural and ecologically necessary surface fires and reinforcing
the accelerated erosion. And, several thousand archaeological
sites are being damaged by erosion in the Bandelier area.
While too much bare soil is the root of the problem, eliminating
grazing in this desertified landscape is no panacea for Bandelier's
erosion crisis. Herbivore exclosures established in 1975 show
that protection from grazing, by itself, "fails to promote
vegetative recovery," they write.
Without management intervention, they argue, this human-caused
case of accelerated soil erosion is causing irreversible damage.
They warn, "To a significant degree, the park's biological
productivity and cultural resources are literally washing
away."
Their summation is provocative: "We have a choice when
we know land is 'sick.' We can "make believe," to
quote Aldo Leopold, that everything will turn out all right
if Nature is left to take its course in our unhealthy wildernesses,
or we can intervene — adaptively and with humility —
to facilitate the healing process."
And healing is what Allen is trying to accomplish as he tries
to make ecology relevant.
"Once bare soils are exposed, this becomes is a harsh
environment for plants," Allen said during a hike to
a restoration study site on a dry mesa in Bandelier's wilderness.
"There's pounding rain in the summer, when it rains,
lots of freeze-thaw action in the soil in the winter, when
it snows, and desiccating sunshine and winds in the spring."
These conditions have played havoc on Bandelier's semiarid
and shallow soils – soils which are not atypical of
many around the region.
Which is why Bandelier is a good case study in making the
West "work" again.
Restoration
So what is a modern land manager to do in face of this persistent
"erosion crisis?" Allen and other ecologists have
an idea: restore the natural range of variability to the land.
In other words, get natural processes, especially water retention
and fire, up and running again.
He explained the strategy at the restoration site.
"In 1997, crews came in here and cut the smaller trees,
lopped the branches and spread everything out over the land,"
he said. "The idea was to get a more natural water cycle
going by allowing more infiltration by rain so grass would
grow. We wanted to do this by improving microenvironments
in the bare interspaces between grass clumps and trees, and
we did that with the slash."
"There was an immediate response," said Allen. "Erosion
nearly ceased, remnant grass bunches started growing again,
a weedy successional cycle started, and new plants grew."
The slash did this, according to Allen, for three reasons:
The branches and needles increased "surface roughness"
by creating a "zillion" little checkdams that held
back water and soil; the foliage provided a pulse of nutrients
to plants and seeds; and shading by the branches reduced evaporation
and the stress on plants.
"By reducing the harshness of the microenvironment,"
he said, "we increased the amount of plant-available
water, which is essential to grow plants that slow and stop
sheet erosion."
If rain runs off too quickly, grass and plants can't grow,
and if grasses can't grow, they can't be become fuel for a
fire, and if a fire can't run its course, then too many trees
grow, which compete with grasses and further reduces the amount
of ground cover, which encourages additional erosion - round
and round it goes, as it has for nearly a century.
When Allen and other scientists compared the restoration site
to an adjacent "control" watershed that did not
receive treatment, they were pleasantly surprised by the results.
"Overall herbacious biomass went up four-fold,"
Allen said, "and sediment yield dropped a hundred-fold.
Biodiversity and abundance went up, too. We even started to
see many more butterflies because the plants were flowering."
"It was very encouraging," he continued. "It
showed us that you can kick-start natural processes again
without too much work or money. We didn't plant any seeds.
All we really needed were chainsaws." ... In a wilderness
area.
New Approach
All of this represents a new approach to restoration. First
and foremost, it's humble.
"We can't erase history," Allen noted, "but
what we can do is encourage ecological processes to function
again as naturally as possible. And continue to learn and
be ready to admit mistakes."
Allen is the first to acknowledge they don't know when they
will reach the endpoint of this experiment exactly, but he
does know they can't be actively managing it forever.
"We don't want to be endlessly intervening, deciding
who lives and who dies out here," he says. That's why
their approach has the goal of letting nature take over as
soon as possible.
Their basic approach is also practical. Allen thinks this
"mulching" method will appeal to landowners because
of its simplicity. Outside of designated wilderness, or on
a larger scale, with larger trees, he recommends also trying
a "splatterer" – a machine on rubber tires
that "eats" trees from the top down using a fast-spinning
rotary head and a rotating cab.
The irregularly shaped debris from this process is "splattered"
for 200 feet in a random manner that Allen considers to be
natural enough.
"Chipping" he said, "doesn't do it," because
small uniform chips tend to blanket soils, choking grass and
tying up too much nitrogen.
"Popping trees out of the ground may not be enough either,"
he warned. "You're just reducing tree competition, not
addressing the problem of poor water cycling." Removing
a piñon or juniper does not necessarily mean the grass
will return, he notes. Often additional work is required,
such as mulching.
Don't lose sight of the ultimate goal, he reminds us –
which is to get fire back into the system.
Allen candidly admits that their approach may not be ideal
for everyone, but he said some sort of approach is urgently
needed.
"We've got 100,000-year-old soils in Bandelier that will
be gone in two centuries if we don't do something," he
said. "Some might argue that we should sit back and let
nature take its course, but I'm not one of them them when
people have clearly caused the problem."
Once ecosystems have crossed a threshold, as they have in
Bandelier and many other places, hands-off protection does
not help much, he says. Action is required.
"Aldo Leopold observed 80 years ago that many Southwestern
ecosystems were in trouble," said Allen. "They're
still in trouble. We know now they've fallen out of their
natural range of variability. The difference is today we know
enough to make progress in repairing the damage."
That is in large part due to scientists like Craig Allen.
"We don't know it all," said Allen, "but we
know enough to get started."
Citation: "Would Ecological Landscape
Restoration Make the Bandelier Wilderness More or Less of a
Wilderness?" by Charisse Sydoriak, Craig Allen, and Brian
Jacobs. In "Wild Earth," Winter 2000/2001, pp.83-90.
|
Courtney
White writes