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Subtle threats could ruin the Amazon rainforest
An interview with Amazon scientist Dr. Carlos Peres
Rhett A. Butler,
mongabay.com
November 7, 2007
While the mention of Amazon destruction usually conjures up images
of vast stretches of felled and burned rainforest trees, cattle
ranches, and vast soybean farms, some of the biggest threats to the
Amazon rainforest are barely perceptible from above. Selective
logging -- which opens up the forest canopy and allows winds and
sunlight to dry leaf litter on the forest floor -- and 6-inch high
"surface" fires are turning parts of the Amazon into a tinderbox,
putting the world's largest rainforest at risk of ever-more severe
forest fires. At the same time, market-driven hunting is
impoverishing some areas of seed dispersers and predators, making
it more difficult for forests to recover. Climate change -- and its
forecast impacts on the Amazon basin -- further looms large over
the horizon.
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Dr. Carlos Peres in the forest along the Rio Roosevelt in the
Brazilian Amazon
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Few people understand these threats better than Dr. Carlos Peres of
the University of East Anglia, a native Brazilian who grew up in an
Amazonian city with the rainforest as his backyard. Through
affiliations with a roster of universities, Peres has worked
extensively in the Amazon on topics ranging from surface fires to
wildlife ecology to sustainable development. He has been honored by
Time Magazine as an "Environmentalist Leader for the New
Millennium" (2000), published more than 150 papers, and recently
co-edited a definitive book on tropical deforestation (Emerging
Threats to Tropical Forests).
In a November 2007 interview with mongabay.com, Peres fielded
questions about his work, his outlook for the Amazon forest, and
the challenges facing rainforest conservation efforts.
INTERVIEW WITH DR. CARLOS PERES
Mongabay: What is the focus of your research?
Peres: Over the last 25 yrs, I've courted a variety of
themes in ecology and conservation in over 80 Neotropical forest
sites, but the main unifying focus is to understand the effects of
land-use change, large-scale habitat disturbance and game harvest
on tropical forest biodiversity. For example, I've worked on the
effects of forest fragmentation, selective logging, surface fires,
slash-and-burn agriculture, secondary succession, forest conversion
to fast-growing tree monocultures, and subsistence hunting on
forest wildlife. I'm also interested in more fundamental questions
in relation to large-scale spatial patterns of population abundance
and species diversity in tropical forests, and how those are
governed by baseline environmental gradients like rainfall
seasonality, geochemistry, soil fertility and floristic
composition.
Mongabay: How did you become interested in this area?
What is your background?
Peres: I was fortunate to be born and educated in
a major Amazonian city in the 1960s, with the world's largest
tropical forest in my backyard, when less than 1% of Brazilian
Amazonia had been deforested. I've been interested in animals, both
small and large, for as long as I can remember. My mother recalls
that I followed columns of harvest ants for hours around our house
before I could even walk properly. That interest gradually morphed
into several naturalistic hobbies which flourished in my father's
~3,500-hectare landholding (97% of which was primary forest) along
the Rio Acará (90 km south of Belém) which was also a spiritual
retreat. At the young age of 16, I later became a research intern
at Museu Emílio Goeldi in Belém (the premier Amazonian Natural
History research institute) and had the fortune of joining many
collecting expeditions and working for 4 yrs with the leading
zoologists and botanists plowing their trade in the Amazon in the
early 1980s. By then I was avid to take my chances and follow a
science career in tropical ecology and conservation. So my
background is very eclectic and I've worked on the population and
community ecology of Neotropical forest trees, seedlings,
arthropods, freshwater fishes, herps, birds and mammals, and in
both disturbed and undisturbed forests.
Mongabay: Do you have any advice for students hoping to
become conservation scientists?
Peres: Perseverance and persistence. In today's
severely competitive world, it's not exactly straightforward to
conquer a career in tropical conservation, but the opportunities
are there for the most obstinate students who are prepared to go to
great lengths to earn a place in the sun. But there are many ways
one can become useful in conservation, and that includes
conservation policy, advocacy and action, so conservation science
is not the be-all and end-all for everyone.
Mongabay: What is you favorite place in the
tropics?
Peres: That's a really tough choice, but it would
have to be a wide swathe of Amazonian seasonally flooded forest
(várzea or igapó) at its maximum water-level when you can canoe
your way silently through the midstorey early in the morning, at
almost eye-level with the subcanopy wildlife, some 12 m above where
you'd be walking only 6 months earlier.
Mongabay: What is your outlook for the Amazon in 20 years
time? What do you see as the greatest threats to the ecosystem? Do
you see climate change as a significant threat to the Amazon's
tropical forest ecosystem? What is the impact of
wildfires--especially recurrent burning--on plants and wildlife in
forests that do not typically experience burning?
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Surface fire burning in the Brazilian Amazon. Photo by Jos
Barlow
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Peres: At current rates of deforestation and forest
degradation by logging, wildfires and forest fragmentation, two
decades is a very long time for the Amazon, so the most robust
projections of future forest cover and forest intactness scenarios
look pretty bleak. The pace of government-sponsored agricultural
resettlement programs, road-building, other infrastructure
expansion and ensuing forest conversion is not exactly slowing
down, and we're yet to be able to show that market-integrated
forest dwellers, whether they are indigenous, 19th-20th Century
immigrants, or neocolonists, can make a decent living in the
long-term while coexisting with a reasonably intact forest cover.
But the most extensive threat to the very viability of vast tracts
of closed-canopy Amazonian forest ecosystems is logging, because
timber extraction changes the forest microclimate primarily by
opening up the canopy and drying down the understorey, thereby
eroding the natural immunity of the forest against recurrent
surface fires. Because this was never part of the evolutionary
history of rainforests, most of the Amazonian biota is extremely
sensitive to even low-intensity fires, which can trigger mass
delayed die-offs of trees and woody lianas, thereby adding to the
fuel load and paving the way to even more severe recurrent fires.
And under current scenarios of climate change, the unusual seasonal
droughts that we have seen in the last decade will become even more
severe and more frequent, exacerbating the spread of the onset of a
fire-dominated disturbance regime that, as we have shown in our
work, will dramatically impoverish the structure and species
composition of Amazonian forests, in many cases irreversibly. As a
result of recurrent fires and wholesale mortality of old-growth
canopy trees, high-biomass closed-canopy primary forests can
gradually slip into a system dominated by low-biomass trees and
shrubs with fast life histories that is more akin to a scrubby
secondary forests, and this has huge implications to both
biodiversity retention, water cycling and carbon storage.
Mongabay: How important, in terms of scale and impact on
biodiversity, is hunting in tropical forests?
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Three White-lipped peccaries entering a village on the way to the
pot. Photo by Luke Parry
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Peres: Game harvest is arguably the most widespread form of
tropical forest disturbance, and amounts to profound consequences
to the structure of large vertebrate communities. Yet hunting is a
diffuse and relatively invisible activity that takes place
underneath the canopy and is virtually undetectable at large
spatial scales so this cannot be easily mapped using any
conventional remote sensing approach from the comfort of your
armchair. Admittedly, hunting only affects a very small proportion
of all vertebrate species in a tropical forest because in most
cases both subsistence and commercial hunters cannot afford to be
unselective, and most species are too small and simply not worth
pursuing. However, the large-bodied vertebrate fauna that is
frequently decimated by overhunting has a disproportionately large
contribution to the structure and functioning of these ecosystems
in terms of their high crude biomass, their trophic roles, as
agents of physical disturbance, and their direct or indirect
ecological interactions with other species which often govern plant
reproductive fitness. The bottom-line is that a tropical deciduous
or a tropical evergreen forest without the large mammals, large
birds and large reptiles with which they have evolved can never be
defined as an intact, healthy ecosystem — complete with all its
constituent parts — no matter how undisturbed the physical
structure of the forest appears to be. And seeing the wood for the
trees in a tropical forest means that you have to consider the full
complement of species in what were once pristine forest systems,
replete with all creatures great and small.
Mongabay: What is the best way to address hunting?
Peres: Game harvest in itself is not a bad thing.
Subsistence hunters one way or the other can help justify
maintaining forest wildlife habitat in millions of hectares in the
form of extractive and indigenous reserves, just like recreational
game hunting can be a huge boost to wildlife conservation in many
temperate countries. The problem is that local game populations
need to be managed carefully, and in tropical forests worldwide
we're still a long ways off from being able to do that — not least
because we still lack the basic information, implementation tools
and know-how that is grounded in applied ecological research. As a
consequence, many game species are often severely overhunted or
driven to local extinction. For a start, the safest way to protect
many harvest-sensitive game species is to make sure that
sufficiently large populations are effectively protected from any
kind of harvest in different categories of forest reserves. But
these reserves will unavoidably account for but a relatively small
proportion of the ecological distribution of these species, so we
also need to work with local [tribal and nontribal] communities who
depend on wildlife resources both within legally occupied protected
areas and outside formal reserves. In some cases these resources
can be co-managed by local communities and there are a number of
measures that can help spread the burden of hunting pressure both
spatially and across game species of varying desirability and
resilience to hunting, thereby prevent overharvesting of any given
stock. The issue of both small and large domestic livestock
substitution remains controversial, but in some cases that, too,
can help relieve the pressure on those species that are most
susceptible to population declines where hunting can and should
take place. But some low-fecundity species are just too sensitive
to even low-intensity offtakes, and although those could also be
managed in theory, it is extremely difficult to be able to achieve
truly sustainable harvests in practice, so in many cases those
populations will be safest if they are not harvested at all at any
given site, either temporarily or permanently. Finally, in many
tropical forest countries we still lack the basic institutional
framework, rural extension mechanisms and a technical advisory
protocol that can ensure the link between what we already know now
about natural resource management and the implementation of
management policies at local, regional or national scales.
Mongabay: What have you learned from indigenous use of
forest resources in the Amazon?
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A young Kaxinawa hunter with a howler and a white-faced capuchin
monkey. Photo courtesy of Dr. Peres
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Peres: Indigenous peoples are not necessarily wise guardians
of the forest and forest resources. For centuries and millennia
they were able to coexist harmoniously with relatively intact
systems because these populations in almost all cases were very
sparsely settled, and there were many density-dependent mechanisms,
such as diseases, warfare, and mutual avoidance, to keep their
numbers and distribution in the landscape in check. Unlike many
parts of the Old World, they also lacked the technology to impart
rapid wholesale changes in the structure of the ecosystem. Having
said that, I am a profound admirer of the way Indians live and have
worked with three indigenous groups in different poles of the
Amazon who have taught me a great deal about the forest. In many
cases, many generations of trial and error experimenting with the
flora have molded a body of ethnobotanical knowledge that is
unrivalled anywhere else. Yet, slowly but surely, these populations
are still losing out to outside conquistadores, so we must make
sure that we can ensure indigenous territorial rights, and most
importantly be able to work with them as the logging, mining and
agricultural frontiers inevitably close in on them.
Mongabay: What do you see as the best way to protect
tropical ecosystems and conserve biodiversity for future
generations?
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The Amazon forest going up in flames. Photo courtesy of Dr. Carlos
Peres
Slash-and-burn plot after a deforestation fire in Alta Floresta in
the Brazilian Amazon. Photo by Alex
Lees
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Peres: The backbone of any national scale strategy to ensure
the persistence of all species in any native biota well into the
future has to be a robust, representative network of sufficiently
large protected areas that are created and implemented by the state
or federal government. In the case of tropical forests, these
preserves should always ensure largely intact forest cover but to
some degree they could vary in the form in which they can be used,
all the way from strictly protected areas that exclude all
consumptive uses to those that are occupied by manageable numbers
of legal residents harvesting sustainable quotas of nontimber
forest products. This basic strategy should also be complemented by
other approaches such as forest reserves inside private
landholdings, benign extractive and forestry activities in the
wider unprotected forest matrix, and appropriate design of
landscapes dominated by agro-forestry or conventional agriculture.
But given the socioeconomic realities of different countries, the
opportunities and financial viability of creating sizeable
protected areas of old-growth forest are rapidly diminishing, so it
is crucial that we act sooner rather than later. And there is also
the issue of permanence in that most protected areas, or the
legislation ensuring their status continuity, will come under
mounting pressure as the world's last tropical forest regions are
developed and rural populations grow, so it is crucial that
protected areas are designed and created to endure the test of
time. This may require continuous vigilance on the part of national
and international conservation organizations, and field and/or
remote-sensing based monitoring programs so that we can be sure
that these conservation units are performing well and delivering
their original biodiversity conservation objectives.
Mongabay: What can the general public do at home to
help?
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Dr. Peres's PhD study area in the Urucu (700 km southwest of
Manaus) showing a vast landscape of completely undisturbed forest.
Photo courtesy of Dr. Peres
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Peres: Ordinary well-meaning people can support conservation
organizations that strive to minimize trickle-down administrative
inefficiencies by plowing most, if not all, of their conservation
dollars or euros directly into sound biodiversity conservation
projects on the ground. But there's also a policy arena that anyone
can influence by lobbying politicians and decision-makers, and
becoming involved in the main conservation debates of our times.
But to do that, concerned citizens will have to think globally and
beyond local constituencies because the most decisive conservation
problems of our times may be happening in far-flung places that we
may never have a chance to see.
About Dr. Carlos A. Peres
Carlos Peres, born in Belém, Brazil (1963); Tropical forest
ecologist and Conservation Biologist; originally trained as a
tropical field biologist and tropical agronomist. Education:
University of Pará (Brasil), University of Florida (USA),
University of Cambridge (UK), and Duke University (USA); later a
Professor of Ecology at University of São Paulo (Brasil), and
currently a Reader in Conservation Biology at the University of
East Anglia (UK).
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