This is a repository copy of Increasing human dominance of tropical forests.
White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/93312/
Version: Accepted Version
Article: Lewis, SL, Edwards, DP and Galbraith, D (2015) Increasing human dominance of tropical forests. Science, 349 (6250). pp. 827-832. ISSN 0036-8075 https://doi.org/10.1126/science.aaa9932
© The Authors 2016. This is the author’s version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science (349:6250) on 21st August 2016, DOI: 10.1126/science.aaa9932.
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[email protected] https://eprints.whiterose.ac.uk/ Increasing Human Dominance of Tropical Forests
Simon L. Lewis1,2, David P. Edwards3 & David Galbraith2
1Department of Geography, University College London, London, UK. 2School of Geography, University of Leeds, Leeds, UK. 3Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
Nontechnical Abstract
T E the climate system. These forests are experiencing escalating human influence, altering their health and the provision of important ecosystem functions and services. Impacts started with hunting and millennia-old megafaunal extinctions (Phase I), continuing via low-intensity shifting cultivation (Phase II), to P III), dominated by intensive permanent agriculture, industrial logging, and attendant fires and fragmentation. Such ongoing pressures together with an intensification of global environmental change may severely degrade forests in the future (Phase IV, glob alongside climate change resilient landscape designs.
Main Article
The functioning of Earth is dominated by the redistribution of incoming solar radiation through fluxes of both energy and matter, within which life plays a pivotal role. Tropical forests are critical to this functioning as a major regulator of global climate, via water transpiration, cloud formation and atmospheric circulation (1-3). Overall, they exchange more water and carbon with the atmosphere than any other biome: changes in the balance of photosynthesis and respiration in tropical forests dominate inter- E CO2 concentration (4). Furthermore, over half of E -20 million species reside in tropical forests (5, 6).
Some 1.2-1.5 billion people directly rely on tropical forests for food, timber, medicines and other ecosystem services (7), including both closed-canopy and more open seasonal systems (Fig. 1). This multiplicity of forest functions and services are underpinned by their diverse resident species, such that diverse forests are healthy forests (8). Here we consider threats to tropical forests and their impacts on forest health and the ecosystem services they supply in three parts. First, historical changes since humans began living in the tropical forest biome, because impacts can last millennia; second, the much greater changes over recent decades; and third, the future of tropical forests given the twin pressures of further agricultural expansion and rapid global environmental change.
Historical human impacts on forest health
There are five major biogeographic regions in the moist tropics