Global Effects of Tropical Deforestation: Towards an Integrated Perspective (original) (raw)

Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation

Concerted political attention has focused on reducing deforestation 1−3 , and this remains the cornerstone of many biodiversity conservation strategies 4−6 . Yet maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes 6 . These disturbances occur both within-forests, including selective logging and wildfires 7,8 , and at the landscape level, through edge, area and isolation effects 9 . To date, the total combined effect of anthropogenic disturbance on the conservation value of remnant primary forests is unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. We address these knowledge gaps using an unparalleled data set of plants, birds, and dung beetles (1538, 460 and 156 species, respectively) sampled in 36 catchments in the Amazonian state of Pará. Catchments retaining > 69-80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code 5 , resulted in a 39-54% loss of conservation value, 96-171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, an area larger than South Africa covering 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared to deforested areas, the toll of disturbance outside Pará's strictly protected areas is equivalent to the loss of 92,000-139,000 km 2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 10 . Species distribution models showed that landscape and within-forest disturbance both made substantial contributions to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the mainte-nance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems.

Tropical reforestation and climate change: beyond carbon

Restoration Ecology, 2015

Tropical reforestation (TR) has been highlighted as an important intervention for climate change mitigation because of its carbon storage potential. TR can also play other frequently overlooked, but significant, roles in helping society and ecosystems adapt to climate variability and change. For example, reforestation can ameliorate climate-associated impacts of altered hydrological cycles in watersheds, protect coastal areas from increased storms, and provide habitat to reduce the probability of species' extinctions under a changing climate. Consequently, reforestation should be managed with both adaptation and mitigation objectives in mind, so as to maximize synergies among these diverse roles, and to avoid trade-offs in which the achievement of one goal is detrimental to another. Management of increased forest cover must also incorporate measures for reducing the direct and indirect impacts of changing climate on reforestation itself. Here we advocate a focus on "climate-smart reforestation," defined as reforesting for climate change mitigation and adaptation, while ensuring that the direct and indirect impacts of climate change on reforestation are anticipated and minimized.

A multi-region assessment of tropical forest biodiversity in a human-modified world

Biological Conservation, 2010

The fate of much of the world's terrestrial biodiversity is linked to the management of human-modified forest landscapes in the humid tropics. This Special Issue presents the first pan-tropical synthesis of research on the prospects for biodiversity in such systems, with eight individual regional summaries covering Mesoamerica, Amazonia, Atlantic forest of South America, West Africa, Madagascar, Western Ghats, Southeast Asia and Oceania. Two additional papers compare the state of conservation science in tropical forests with both temperate forests and savannah systems. This overview paper provides a comparative analysis of the threats and opportunities facing tropical forest biodiversity, thereby helping to identify the most pressing areas of future research and region-specific factors that contribute towards the effectiveness of individual conservation initiatives. While many of the threats facing tropical forest biodiversity are commonplace they vary markedly in their relative importance across different regions. There is a critical lack of comparable data to understand scale dependent processes, or the relative importance of varying geographic and historical contexts in determining present-day patterns. Conservation science has a key role to play in safeguarding the future of tropical forest biodiversity, but needs to become more effectively embedded in the context of real-world conservation challenges and opportunities. Significant progress can be achieved by improving the cost-effectiveness of research as well as the exchange of ideas and data amongst scientists working in different, often isolated parts of the world. We hope this special issue goes some way top achieving this exchange of knowledge.

Manuscript 2012-02-02558B Averting biodiversity collapse in tropical forest protected areas

2016

Author contributions W. Laurance conceived the study and coordinated its design, analysis and manuscript preparation. D. Useche, J. Rendeiro and M. Kalka conducted the interviews; C. Bradshaw assisted with data analysis and some writing; and S. Laurance, S. Sloan, M. Campbell and W. Logsdon organized data or collected metadata. The remaining authors provided detailed interviews on protected areas and offered feedback on the manuscript.

Loss in Species Caused by Deforestation and Their Recovery through Management

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ICLE Tropical reforestation and climate change : beyond carbon

2015

Tropical reforestation (TR) has been highlighted as an important intervention for climate change mitigation because of its carbon storage potential. TR can also play other frequently overlooked, but significant, roles in helping society and ecosystems adapt to climate variability and change. For example, reforestation can ameliorate climate-associated impacts of altered hydrological cycles in watersheds, protect coastal areas from increased storms, and provide habitat to reduce the probability of species’ extinctions under a changing climate. Consequently, reforestation should be managed with both adaptation and mitigation objectives in mind, so as to maximize synergies among these diverse roles, and to avoid trade-offs in which the achievement of one goal is detrimental to another. Management of increased forest cover must also incorporate measures for reducing the direct and indirect impacts of changing climate on reforestation itself. Here we advocate a focus on “climate-smart re...

Averting biodiversity collapse in tropical forest protected areas by Laurence et al

Nature, 2012

The rapid disruption of tropical forests probably imperils global bio- diversity more than any other contemporary phenomenon1–3. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are them- selves vulnerable to human encroachment and other environmental stresses4–9. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environ- mental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

Tropical moist forests: destruction and species extinction

Biological conservation, 1991

Tropical moist forests are currently being altered or destroyed at a rapid rate. A 1980 assessment by the Food and Agricultural Organisation (FA O)for all tropical countries has now been superseded for some by new assessments based largely on more recent satellite imagery. Comparison of different estimates are complex because of different definitions of'forest ', 'alteration', 'degradation'and 'destruction'. Making allowance for these problems, the new estimates show that rate of deforestation has, in general, increased.

Have we overstated the tropical biodiversity crisis?

Trends in Ecology & Evolution, 2007

Tropical forests are the most biologically diverse and ecologically complex of terrestrial ecosystems, and are disappearing at alarming rates. It has long been suggested that rapid forest loss and degradation in the tropics, if unabated, could ultimately precipitate a wave of species extinctions, perhaps comparable to mass extinction events in the geological history of the Earth. However, a vigorous debate has erupted following a study by Wright and Muller-Landau that challenges the notion of large-scale tropical extinctions, at least over the next century. Here, I summarize this controversy and describe how the debate is stimulating a serious examination of the causes and biological consequences of future tropical deforestation.