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Shifting dynamics of climate-functional groups in old-growth Amazonian forests

2012; Taylor & Francis; Volume: 7; Issue: 1-2 Linguagem: Inglês

10.1080/17550874.2012.715210

1755-1668

Nathalie Butt, Yadvinder Malhi, Mark New, Manuel J. Macía, Simon L. Lewis, Gabriela López‐González, William F. Laurance, Susan G. W. Laurance, Regina C. C. Luizão, Ana Andrade, Timothy R. Baker, Samuel Almeida, Oliver L. Phillips,

Plant Water Relations and Carbon Dynamics

Abstract Background: Climate change is driving ecosystem shifts, which has implications for tropical forest system function and productivity. Aim: To investigate Amazon forest dynamics and test for compositional changes between 1985 and 2005 across different plant groups. Methods: Tree census data from 46 long-term RAINFOR forest plots in Amazonia for three climate-functional groups were used: dry-affiliate, climate-generalist and wet affiliate. Membership of each group was ascribed at genus level from the distribution of individuals across a wet–dry gradient in Amazonia, and then used to determine whether the proportions of these functional groups have changed over time, and the direction of any change. Results: In total, 91 genera, representing 59% of the stems and 18% of genera in the plots, were analysed. Wet-affiliates tended to move from a state of net basal area gain towards dynamic equilibrium, defined as where gain ≈ loss, governed by an increase in loss rather than a decrease in growth and mainly driven by plots in north-west Amazonia, the wettest part of the region. Dry-affiliates remained in a state of strong net basal area gain across western Amazonia and showed a strong increase in stem recruitment. Wet-affiliates and climate-generalists showed increases in stem mortality, and climate-generalists showed increased stem recruitment, resulting in overall equilibrium of stem numbers. Conclusions: While there were no significant shifts in most genera, the results suggest an overall shift in climate-functional forest composition in western Amazonia away from wet-affiliates, and potential for increased forest persistence under projected drier conditions in the future. Keywords: climate trendsforest compositionmoisture affiliationmoisture seasonalitytropical forest Acknowledgements N. Butt's Ph.D. was funded by the UK Natural Environment Research Council. We thank those who contributed field data: L. Arroyo, F. Cornejo, N. Higuchi, E. Honorio, I. Huamantupa, N. Jaramillo, R. Luizão, A. Monteagudo, D. Neill, A. Pena Cruz, J. Pipoly, J. Terborgh, M. Silva, P. Nuñez, and R. Vasquez. Thanks also to Toby Marthews for his help with R coding. Funding for plot monitoring in Amazonia was provided by grants to OP and YM from NERC, the EU Framework V, and the National Geographic Society. OP is supported by an Advanced Grant from the European Research Council. Simon L. Lewis is supported by the Royal Society. The manuscript was improved by comments from Lourens Poorter, Sharon Strauss and two anonymous referees. This paper is dedicated to the memory of co-author Samuel Almeida, a committed Amazon forest ecologist who passed away during the preparation of the manuscript. Table 3. Comparison of changes for the dry-affiliate group by including vs. excluding Aspidosperma Download CSVDisplay Table Notes + Died 2011.