REVIEWS REVIEWS REVIEWS
Amnazonia
loss
of
Amazon
revealed:
ecosystem
forest
goods
degradation
and
services
in the
and
Basin
Jonathan A Foley', Gregory P Asner2, Marcos Heil Costa3,Michael T Coe4, Ruth DeFries5, Holly K Gibbs',
Erica A Howard', Sarah Olson', Jonathan Patz', Navin Ramankutty', and Peter Snyder6
The Amazon Basin is one of theworld's most important bioregions, harboring a rich array of plant and animal
species and offering awealth of goods and services to society. Foryears, ecological science has shown how large
scale forest clearings cause declines in biodiversity and the availability of forest products. Yet some important
changes in the rainforests, and in the ecosystem services they provide, have been underappreciated until
recently.Emerging research indicates that land use in theAmazon goes farbeyond clearing large areas of forest;
selective logging and other canopy damage ismuch more pervasive than once believed. Deforestation causes
collateral damage to the surrounding forests - through enhanced drying of the forest floor, increased frequency
of fires, and lowered productivity. The lossof healthy forests can degrade key ecosystem services, such as carbon
storage in biomass and soils, the regulation of water balance and river flow, themodulation of regional climate
patterns, and the amelioration of infectious diseases.We review these newly revealed changes in the Amazon
rainforests and the ecosystem services that they provide.
FrontEcolEnviron2007; 5(1): 25-32
T
he Amazon Basin isgenerally regardedas one of the Raven 2003), including a rich arrayof plant, animal, and
world's most important ecological systems, mainly microbial life-forms,which are vital for the functioning of
because it includes the largest remaining area of tropical the biosphere.
The rainforests of the Amazon also provide crucial
rainforest (Figure 1). These forestscontain one of Earth's
greatest collections of biological diversity (Dirzo and ecosystem goods and services to humanity, includingmany
thathave considerableeconomic and societal value (Myers
The term "ecosystem goods and services" has
1997).
In a nutshell:
become widely used in recent years, and typically refers to
*While tropical deforestation is a well-known environmental
the supply of valuable products and materials (including
problem, many aspects of this issue have been overlooked
agricultural,
forest,mineral, and pharmaceuticalcommodi
until recently
ties), the supportand regulationof environmental condi
* The degradation of tropical rainforests goes far beyond clear
ing large areas of trees; selective logging, collateral forest
tions (through processes like pollination, flood control,
damage, and the replacement of old growth stands are also
and water purification), and the provision of cultural and
widespread
* Inadditiontoprovidingagricultural
and timbercommodities aesthetic benefits (including ecotourism, heritage, and
sense of place) by ecosystems (Daily 1997; Millenium
these landscapes may also sequester carbon, regulate fresh
EcosystemAssessment 2003; DeFries et al. 2004).
water and river flows, modulate regional patterns of climate,
diseases
andameliorateinfectious
Many of the ecosystem goods and services derived from
* The loss and degradation of tropical rainforests and the ser
the Amazon Basin (eg from timber,pasture, and soybean
vices they provide may be greater and more widespread than
production), are easily recognizedand are revealedon local
previouslyreported
scales- often within individual landparcels that are specif
icallymanaged for those purposes.Other ecosystem ser
vices, such as pollination and flood control, are somewhat
'Center for Sustainability and the Global Environment (SAGE),
less obvious and may appear over larger spatial scales,
Nelson Institute for Environmental Studies, University ofWisconsin,
extending over complex landscapesandwhole watersheds.
Madison, WI 53726; 2Department of Global Ecology, Carnegie
Institution of Washington, Stanford, CA 94305; 3Department of
Tropical rainforestsalso provide ecosystem services that are
manifested at the scale of the whole Amazon Basin and,
Agricultural and Environmental Engineering, Federal University of
indeed, the planet. For example, rainforestsin theAmazon
Viqosa, Viqosa, MG 36571-000, Brazil; 'Woods Hole Research
Center, Falmouth, MA 02543; 5Department of Geography and
sequestercarbon from the global atmosphere, regulate the
water balance and flow of the entireAmazon River system,
Earth System Science Interdisciplinary Center, University of
influence the patterns of climate and air chemistry over
Maryland, College Park, College Park,MD 20742; 6Department of
much of the continent, andmay even ameliorate the spread
Atmospheric Sciences, University of Illinois, Urbana, IL 61801
ofAmerica
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Society
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Forestdegradation in theAmazon
JA Foley et at.
forest clearance in the Basin (eg Skole and
Tucker 1993; Morton et al. 2005). These
efforts have given us themeans to quantita
tively describe the amounts and spatial pat
tems of deforestation. For example, we now
know that deforestation is largely focused in
the transition areas between forest and cer
rado (tropical savanna), along roads, and in
the frontier border areas such as Acre and
Rond-nia (Houghton et al. 2000; Cardille
and Foley 2003; Soares-Filho et al. 2004).
Nevertheless, there are still many gaps in
our understanding of Amazon deforestation.
Until recently, characterizing deforesta
tion from satellites has focusedmainly on
estimating the changing areasof "forest"and
"non-forest" pixels over time. However,
Amazonian landscapes are actually much
more dynamic and complex: they experi
Figure 1. TheAmazonBasin.Map illustrating
thespatialextentof theAmazon ence cycles of clearing, cultivation, grazing,
on a vegetationmap of the and secondary forest regrowth, resulting in a
drainagebasinacrossSouthAmerica, superimposed
region.Green indicatesthecurrentdistribution
of forest,whereas tanandwhite complex mosaic of intact rainforest, lands
indicateareas of deforestationand non-forest, respectively.The geographic under varying management regimes, and
locationof major roads is also indicated:black linesare paved roads,grey are recovering secondary forests (Fearnside
1993;Nepstad et al. 1999;Cardille and Foley
unpavedroads,anddashedlinesindicateroadsthatare scheduledtobepaved.
2003). "Forest" and "non-forest" are not
of vector-borne andwater-borne diseases across the region. adequate descriptions of the real landscape. Unfor
But the long-term sustainability of Amazonian rain
tunately,we still do not have a complete understanding of
forests, and themultiple goods and services they provide,
the landscapedynamics of the Basin, that reflects the dif
ferent rates of gross deforestation (clearing of primary
may now be under threat from human actions. The
region has been experiencing high rates of deforestation rainforest to establish pastures or croplands), the widely
varying management regimes of croplands and pastures,
formany years, and thismay now be affecting the ecolog
ical integrityof the forests.By the year 2000, nearly 15% the abandonment of fields leading to regrowth of sec
of the forests in the basin (-400000-500000 kmi2)had ondary forests (followed by possible reclearance), and the
already been cleared (Nepstad et al. 1999). Recent rates resulting net changes in forested area (gross clearing
of deforestation continue to be very high; between 2002 minus regrowth;Figure 2). In particular, it iscrucial to dis
and 2004, the highest rateof forestclearing for any 3-year tinguish regionsof regrowingsecondary forest, as they pro
period to date was recorded (INPE 2004). This trend is vide areasof carbon uptake (Houghton et al. 2000), tem
likely to continue as more roads are built through the porary reservoirsof genetic diversity, and some level of soil
core of the forest, and growing internationalmarkets for conservation and flood amelioration.
Selective logging representsan even greater gap in our
free-rangebeef and soybeans drive increasingdemand for
agriculturalproducts (Carvalho et al. 2001; Alencar et al. knowledge. Until recently, clearing forests for croplands
and pastures has received themost attention in scientific
2004; Soares-Filho et al. 2004).
Here we review recent research on changes in the and political arenas (Houghton et al. 2000; Achard et al.
Amazon rainforestsand the ecosystem goods and services 2002; Defries et al. 2002), but selective logging has now
they provide.Many of these resultsbuild upon our previous become recognized as another major form of land use in
the Amazon. In a ground-breaking estimate of logging
notions of deforestation and the subsequent loss of biodi
versity and ecological functioning. However, some new activity, based on surveys of mill operators, Nepstad
et al. (1999) reported that the extent of logging
resultshave dramaticallychanged our perceptions of defor
estation, the ecological and societal value of the tropical (-9000-15 000 km2per year in 1996-97) nearlymatched
rainforests, and how changes in the forest may affect the amount of gross deforestation occurring in the same
human relationshipswith these unique ecosystems.
period.Using a new, high-resolution satellite analysis sys
tem, Asner et al. (2005) found that selective logging
over more than 12 000 km2 each year between
extended
* Revisiting deforestation in the Amazon
1999 and 2002, with some years seeing rates as high as
20 000 km2yr-. More surprisingwas the finding that this
Many previous studies have used satellite-based
"snapshot" imagesof forest cover to estimate the ratesof newly detected logging only overlappedwith older defor
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JA Foley et al.
Forestdegradation in theAmazon
estation maps - provided by the
1 50
Brazilian Space Institute (INPE
2004) - by about 6%. Even more
unexpected was the finding that
only 16% of the logged area turned
.35
into deforested (clear-cut) land the
~30
following year, and only 32% of the
logged forests were consumed by
~25
clear-cut deforestation within 4
- - - - - --- - - - - - - - - - -- - - - - -- years (Asner et al. 2006). These
20 0 15. . . . . ..
.-- .
results completely change our view
of logging as a form of land use in
theAmazon: first, selective logging
often matches, and can even
O10
I
exceed, deforestation each year;
second, for the most part, logging
does not immediately precede
deforestation - it is a distinct form Figure 2. Gross versusnet deforestation.
Deforestationin theAmazon isnot just thesimple
of forestdisturbance in and of itself. removalof trees.A more completedescription
must considerthedifferentratesof gross
In short, the footprint of human deforestation (clearing of rainforest for pastures or croplands), themanagement regimens of
activity on the Amazon landscape croplandsand pastures, theabandonmentof fields leadingto the regrowthof secondary
is roughly double that of previous forests,and theresulting
net changesinforestedarea (grossclearing
minus regrowth).
Here
estimates of deforestation alone we have adapted a Markov land-use transition model developed by Fearaside (1993) to
(Asner et al. 2005).
estimate that roughly a third of the total deforested land in theAmazon between 1961 and
The ecological impactsof logging 1997 iscurrentlyregrowing
(seealsoCardilleandFoley[2003]). (M= megatons.)
are quite different than those of
clear-cutting, and vary dramatically across the basin. In
These recent studies highlight previously underappreci
some areas, logging is highly selective because interna ated manifestations of land use in the Amazon and
tionalmarkets accept only a few tree species for use as tim
underscore the realization that the degradation of the
ber.However, in areas that supply lumbertoBrazilianmar
Amazon rainforestmay be farmore pervasive than previ
kets, only about 80 species are acceptable (Verissimoet al. ously believed. Taken together, this research forces us to
1995). Such variations in logging practices lead to con
adopt a new perspective on the changing nature of these
comitant variations in forestdamage.Canopy openings in forests, requiring a new look at the ecological implica
the eastern and centralAmazon can encompass 25-50% of
tions of human land-usepractices inAmazonia.
the total logged area, and up to 30 trees can be damaged
with each tree harvested (Asner et al. 2004). The extent * Assessing the ecological impacts of forest decline
and intensity of harvest operations also determines the
impact on carbon storage and loss of biomass and soils Many previous scientific studies of tropical deforestation
(Kelleret al. 2004), the stocks and flowsof importantplant focused on the negative consequences for biodiversity
nutrients, and long-term patterns of forest production and ecosystem functioning (eg Turner 1996; Laurance et
(Olander et al. 2005).
al. 1998). In fact, tropical deforestation has become a
The effects of deforestation and selective loggingmay
cause cele5re among many environmental activists and
also change the local microclimate and fire regimes, NGOs. However, such land-usepractices also offermany
resulting in widespread collateral damage to the forest. benefits.Whether for securing food, freshwater, or raw
For instance, forest clearance and selective logging materials, land use isultimately central to the sustainabil
increase fire occurrence by providing abundant fuel loads ity- indeed, the long-term survival - of all human soci
and forest edges that aremore vulnerable to desiccation
eties (DeFries et al. 2004). Even tropicaldeforestation has
during prolonged periods of dryweather (Laurance et al. positive outcomes: it provides essential resources (eg
1998;Cochrane et al. 1999;Nepstad et al. 1999;Alencar
food, timber, other rawmaterials) to society, as well as
et al. 2004; Barlow and Peres 2004). Under natural condi
badly needed jobs and income tomany developing coun
tions, fires are a rare occurrence in Amazonian rain
triesaround theworld.
forests, so many tree species are highly vulnerable and
Tropical deforestation therefore representsan inherent
can be killed by even low-intensity fires.Such changes in societal tradeoff (DeFries et al. 2004). Ingeneral, land-use
the fire regimemay have contributed to the catastrophic practices allow some ecosystem goods to be more readily
wildfires that consumed millions of hectares of appropriatedby human societies, often yielding key eco
Amazonian forests in 1997-98 (Laurance et al. 1998; nomic and social benefits, at least in the short term.
Nepstad et al. 1999).
However, land use may degrade other ecosystem services
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Forestdegradation in theAmazon
JA Foley et al.
biomass and soil carbon. Inmost instances, a
largeand visible portion of the carbon stored
in vegetation is released rapidly to the
atmosphere through biomass burning. But a
smaller, though still substantial, portion of
and
the carbon is returned to the soil as slash
P~~~~~~~roduct
i/
0
(dead plant materials), or is converted to
* 0 .3
durable products such as paper, lumber,
derived wood products, etc. These carbon
pools decompose slowly and release CO2
over amuch longer timescale (Figure3). As
a result, some CO2 emissions from deforesta
200
1990
1970
14960
CD
tion occur rapidly (from initial clearing and
Regrowth ~~~~~~~~~~~flux
C.)
fire),while others occur graduallyover many
years and decades (from subsequent decom
-0.1
position of slash and forest products;
We haveestimatedthe Houghton et al. 2000). In fact, some of
Figure 3. Estimatedcarbonemissionsfromdeforestation.
over theAmazonBasin from1961-2000, using today'sCO2 emissions may reflect land-use
carbonfluxesfromdeforestation
carboncyclemodel adaptedfromHoughtonet al. (2000). In that activities fromdecades ago.
a bookkeeping
paper,it isnotablethatthelargestfluxesof carbonin the 1980s and 1990sresulted There are some complicating factors to this
from thedecayof accumulatedslashand productpools,and not from theburnt picture. First,many estimates of carbon losses
was of from deforestation only account for gross
regrowth
fluxfromfires.Moreover, thefluxof carbonfromaccumulating
=
as
burnt
deforestation,while the carbon uptake from
the
and
flux. (Gt gigatons.)
opposite sign
equal magnitude
recovering secondary forests is sometimes
- especially those tied to the long-term functioning of the overlooked (Figure 3). Second, deforestation may also
ecosystem. For example, the lossof rainforestsmay reduce indirectly affect carbon storage in nearby forest regions,
throughchanges in local climate and fire regimes (Alencar
several critical ecosystem services, such as the supply of
pollinating
et
of
al. 2004; Barlow and Peres 2004). As noted above, defor
the
availability
forest
products,
non-timber
and selective logging can enhance fuel loads and
and
stocks,
estation
and
carbon
of
climate
insects, the regulation
more vulnerable to desiccation and fire. It is
make
forests
flows.
of
the regulation and purification freshwater
these indirect impacts of deforestation may
regarding
the
possible
that
decisions
more
informed
In order tomake
magnify
the lossof carbon storage across the basin
greatly
it
is
to
bal
necessary
futureof tropical land-usepractices,
et
al.
real
1999;Nepstad et al. 1999).
short-term
(Cochrane
ance the societal benefits (typically the
valuable
ization of ecosystem goods and commercially
commodities) against the long-term costs of ecological Water flow regulation
degradation (Millennium Ecosystem Assessment 2003;
DeFries et al. 2004; Foley et al. 2005). Such an assessment The Amazon is the largestriversystemon Earth, providing
navigablewaters, importantfood sources,hydroelectricity,
of tradeoffsmust be informed by the best available eco
logical science, but ultimately these assessmentsmust also and habitat for countless plants and animals (Lundberget
al. 2000). The forestsof the basin strongly influence this
be based on societal values (DeFries et al. 2004). Recent
complex hydrological system, largelybecause they regulate
research has provided new insights into how deforesta
tion and selective loggingmay negatively affect the flow the volume and timing of water and nutrient flows into it.
of many ecosystem goods and services. Here we review As a result,deforestation has the potential to degrade the
regulationof hydrological flows, through changes in evap
four examples.
otranspiration, canopy interception, surface runoff, and
groundwater recharge (Meher-Homji 1992; Costa and
Carbon storage
Foley 1997;Williams andMelack 1997).
There is now compelling evidence to show that
The forests of the Amazon play a particularly important
role in the Earth'scarbon cycle, as they account fornearly changes in forest cover can affect the water balance and
10% of the world's terrestrialproductivity and biomass hydrology of the Amazon, even if precipitation remains
(Melillo et al. 1996;Malhi andGrace 2000). As such, the constant. Studies of small watersheds (< 10 kM2)
Amazon provides an important ecosystem service to the throughout the tropics reveal that runoff and stream dis
planet by storing organic carbon in biomass and soil, charge generally increasewith increasing deforestation
thereby keeping greenhouse gases (CO2 and CH4) from (Sahin and Hall 1996). In addition, a recent study by
Costa et al. (2003) showed that changes in land cover
the atmosphere.
The reduction or degradation of forest cover can have a substantial effect on large river systems; the
authors examined the links between river discharge and
directly affect carbon storage through lossesof vegetation
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JA Foley et al.
Forestdegradation in theAmazon
vegetation cover in a 176 000 km2 sub
7000 Observed discharge of Tocantins River
catchment of the Tocantins River
6000,
basin in eastern Amazonia and found
.
6000
1950s-60s
co
that land-cover changes between the
5000 --E
-----1980s-90s
1960s and 1990swere associatedwith a
4000
-25% increase in riverdischarge, even
though precipitation in the region did
33000
not change (Figure4).
.2000
At largerscales of deforestation, we
1000
..
have onlymathematical models to rely
upon. Using a detailed biophysical
land surfacemodel, Costa and Foley
J
F M A M
J
J
A
S O
N D
(1997) analyzed the effects of forest
removalon thewater balance and river Figure 4. Effectsof landcoverchangeon riverflow.Here we illustratetheobserved
discharge of the entire Amazon Basin. changesin riverdischargein theTocantinsriverbasin that resultedfrom land-cover
Their resultsshowed that deforestation changeand agriculturalclearingin themid-20th century.The solid line is themean
could produce significant increases in monthly dischargefor theperiod 1950-60s, when cropsand pasturecoveredabout
runoff and river discharge. Averaged 30% of the landareaof the176 000 km2basin.The dotted line is theriverdischarge
across the entire basin, the model duringthe 1980s and 1990s,when cropsandpasturehad increasedtocovermore than
resultssuggested thatwidespread defor 50% of thebasin(adaptedfromCosta et al. 2003).
estation would increase runoff and
riverdischarge by about 20%, although individualwater
European storm tracks, which could cause substantial
shedswithin the basin exhibited increases in discharge cooling in southern Europe and warming across parts of
ranging from between 5 and 45%, depending on the cli
Asia inwinter.
mate, watershed position, and original vegetation cover.
Regional and global climate regulation
The rainforestsof theAmazon play a crucial role in regu
lating the general circulation of the atmosphere.As one
of the threemajor convection centers in the tropics, the
Amazon helps to fuel the Hadley andWalker circula
tions. As deforestation becomes more extensive, the
resulting reductions in evapotranspiration and atmos
pheric heating may weaken moisture recycling and deep
convection in the atmosphere over the Amazon, with
major repercussions for South American climate (eg
Nobre et al. 1991;Costa and Foley 2000). Climate model
simulations of large-scale deforestation in the Amazon
Basin generally show a considerable reduction in evapo
transpirationas tropical forest vegetation is replacedwith
grasses and shrubs; this has the effect of substantially
warming the surface and inhibiting convection, regional
precipitation, and cloud cover (Figure5).
The influence of deforestation on climate may also
extend farbeyond theAmazon Basin. A few recent stud
ies have now illustrated the potential for "teleconnec
tions" from Amazonian climate change, where atmos
pheric signals may propagate into the middle latitudes,
causing changes in the climate of other regions (Snyder et
al. unpublished;Werth and Avissar 2002). Snyder et al.
(unpublished) found that deforestation weakens atmos
pheric convection over the basin and reduces the high
level outflow out of the tropics that interactswith the cir
culation of the atmosphere in themid and high latitudes.
In their simulations, widespread deforestation causes
changes in circulation that alter theNorth Atlantic and
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Vector-borne diseases
Some of the world's most serious infectious diseases,
including malaria, dengue, Leishmaniasis, and several
arboviruses,are found in theAmazon basin.Malaria alone
kills 1.2million people worldwide each year, and approxi
mately 40% of theworld's population lives in areaswhere
malaria is endemic (WHO 2005). In the Brazilian
Amazon alone, there are typically 400 000-600 000 cases
contracted annually (WHO 2005).
Rainforestsmay provide another valuable ecosystem ser
vice, moderating the riskof infectious disease by regulat
ing the populations of disease organisms (viruses,bacteria,
and other parasites), their animal hosts, or the intermedi
ary disease vectors (most often insects or rodents). For
example, the lossof forestcovermay affect the abundance
and behavior of mosquitoes - a common disease vector in
the tropics- throughchanges in local habitat conditions.
Individual mosquito species occupy unique ecological
niches and can react rapidly to changes in habitat. For
example, in Africa, the larvae of Anopheles gambiae are
much more likely to survive in deforested landscapes than
in intact, forestedhabitats (Tuno et al. 2005).
Previous studies conducted in the Amazon indicated
that malaria risk rose sharply during the late 1980s and
1990s (AramburuGuarda et al. 1999). New evidence sug
gests that changes in forest cover, through effects on the
distribution patterns of mosquito vectors, may have con
tributed to this upsurge in the disease. In particular, a
recent project in the Peruvian Amazon examined the
links between deforestation and the principle mosquito
vector formalaria in South America, Anopheles darlingi
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Forestdegradation in theAmazon
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* Summary and conclusions
This is a critical point in the history of the
Amazon Basin, when human stresses could
affect the ecology of the region for decades
and centuries to come. Cross-disciplinary
0
0
scientific research is particularly vital in
helping us to understand how this crucial
region functions, and how itmay be chang
ing. In response, one of themajor priorities
of the Brazilian-led Large-Scale Atmos
300S
300S
phere Biosphere Experiment in Amazonia
(LBA) has been to understand how
Amazonia functions as an integrated entity,
including interactions among terrestrial
ecosystems, freshwater systems, and the
600S600S
atmosphere. Recent research stemming
800W 60VW 400W
80?W 600W
400W
from the LBA, aswell as other efforts, have
already improved our understanding of
human activities and their potential conse
-4 -2
0 2 4
-3-2-1
0 1 2 3
quences for the sustainability of ecosystem
Figure 5. Changes in climateoverAmazonia from completedeforestation. goods and services in the basin.
Snyderet al. (unpublished)used the coupledCCM3-IBIS climate-biosphere Much of this increasedunderstanding has
onAmazonianclimate. resulted from remote sensing observations,
model todeterminetheeffectsof large-scale
deforestation
The resultssuggestthattheAmazon climatemay be highlysensitiveto large-scale intensive and coordinated field measure
ments, and synthetic modeling exercises.
deforestation (adapted from Snyder et al. unpublished).
However. despite this new understanding.
observational and modeling capabilities are still lacking.
(Vittor et al. 2006). This analysis suggests a direct rela
tionship between the extent of deforested land and For example, there is a pressing need to observe smaller
scale patterns of forest degradation by increasing the spa
increasingbiting ratesof A darlingi.In fact, heavily defor
tial or spectral resolution of satellite observations (eg
ested areas can see up to a 300-fold increase in the riskof
Asner et al. 2005; DeFries et al. 2005), and characterizing
malaria infection, compared to areasof intact forest, con
the fate of land use following clearing (egMorton et al. in
trolling for changes in human population density.
Furthermore, there appears to be a threshold effect in press). Others have suggested the need for monitoring
these data:when the landscape is about 20% deforested, changes in forest structure, possibly using active radaror
mosquito biting activity increases substantially. In short, lidarmeasurements (eg Drake et al. 2002; Lefsky et al.
deforestation appears to greatlymagnify mosquito biting 2002). In the end, we must balance the need for these
data, their cost, and competing needs for global environ
ratesand the riskof spreadingmalaria by increasinghabi
mental observation capabilities.
tat available forA darlingi.
Recent assessments of the ecological impacts of land
This work demonstrates that the extent and pattern of
deforestation may degrade the disease regulation services use practices have focused on the need to balance the
tradeoffs resulting from human actions (Millennium
of the rainforest. Specifically, links between deforesta
Ecosystem Assessment 2003; DeFries et al. 2004; Foley et
tion, changes in local habitat conditions and biodiver
sity, and the ecology of A darlingi resulted in greatly al. 2005). In this framework,deforestation is recognized
to have importantbenefits for society, as it increases eco
increased risk of malaria. However, this result could be
even more general; deforestation may also amplify other nomic opportunities and the availability of many ecosys
disease risksaswell (Patz et al. 2005). It is also likely that tem goods, at least in the short term.However, the lossof
changes in forest cover (and associated changes in rivers rainforestsmay also degrademany critical ecosystem ser
and regional climate) could affect human health through vices, such as carbon storage in forests and soils, regula
tion of water balance and river flow, modulation of
changes in food and freshwater availability, or inwater
and air quality. Overall, an important conclusion of atmospheric circulation and regional climate, and the
amelioration of infectious diseases. Thus, the deforesta
these studies is thatmaintaining intact rainforestecosys
tion tradeoff is a balance between realizing short-term
tems may provide many health-related ecosystem ser
gains in selected ecosystem goods, while potentially
vices to the region (Patz et al. 2005).
degrading ecological function and other ecosystem ser
These new scientific results demonstrate the potential
for losingmany important ecosystem services, including vices in the long term.
In this paper,we have distinguished between the local,
some that aremanifest across regional and global scales,
regional, and global effects of deforestation, which also
as tropical forestscontinue to be cleared and degraded.
Change in
temperature (K)
Change in precipitation
(mm day 1)
~~~~~~~~~~~~Ii~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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occur over a wide range of timescales, and the inherent
tradeoffsthey represent.While these cross-scale phenom
ena are increasingly recognized in ecology, it is important
to note that each of these space and time scales (ie local
to global-scale, short- to long-term time horizons) have
profoundly different effects on human society. Each eco
logical scale, in both space and time, potentially interacts
with different groups of people, each with different levels
of vulnerability and control.
Additional research is still needed to quantify the
tradeoffs in ecosystem goods and services resulting from
deforestation, and how they aremanifested across local,
regional, and global scales. Furthermore, continued
efforts are needed to link the scientific quantification of
ecosystem goods and services to policy-relevant terms,
such as economic, political, or cultural valuation, allow
ing formultiple perspectives in the assessmentof the con
sequences of deforestation.
The scientific community hasmade tremendousprogress
in understanding the continued loss and degradation of
Amazonian rainforests,and their connections to human
society.What we have learned is alarming, and reinforces
the need to clearly communicate these new findings to
stakeholdersand decision makers acrossmany levels.
Carvalho
Moutinho
AC,
P,
could
protect
development
it. Nature
131-31.
409:
destroying
Cochrane
MA, Alencar
A, Schulze
in the fire dynamic
of
backs
MD,
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