Publication Date:
2015-03-06
Description:
In 2005 and 2010 the Amazon basin experienced two strong droughts, driven by shifts in the tropical hydrological regime possibly associated with global climate change, as predicted by some global models. Tree mortality increased after the 2005 drought, and regional atmospheric inversion modelling showed basin-wide decreases in CO2 uptake in 2010 compared with 2011 (ref. 5). But the response of tropical forest carbon cycling to these droughts is not fully understood and there has been no detailed multi-site investigation in situ. Here we use several years of data from a network of thirteen 1-ha forest plots spread throughout South America, where each component of net primary production (NPP), autotrophic respiration and heterotrophic respiration is measured separately, to develop a better mechanistic understanding of the impact of the 2010 drought on the Amazon forest. We find that total NPP remained constant throughout the drought. However, towards the end of the drought, autotrophic respiration, especially in roots and stems, declined significantly compared with measurements in 2009 made in the absence of drought, with extended decreases in autotrophic respiration in the three driest plots. In the year after the drought, total NPP remained constant but the allocation of carbon shifted towards canopy NPP and away from fine-root NPP. Both leaf-level and plot-level measurements indicate that severe drought suppresses photosynthesis. Scaling these measurements to the entire Amazon basin with rainfall data, we estimate that drought suppressed Amazon-wide photosynthesis in 2010 by 0.38 petagrams of carbon (0.23-0.53 petagrams of carbon). Overall, we find that during this drought, instead of reducing total NPP, trees prioritized growth by reducing autotrophic respiration that was unrelated to growth. This suggests that trees decrease investment in tissue maintenance and defence, in line with eco-evolutionary theories that trees are competitively disadvantaged in the absence of growth. We propose that weakened maintenance and defence investment may, in turn, cause the increase in post-drought tree mortality observed at our plots.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Doughty, Christopher E -- Metcalfe, D B -- Girardin, C A J -- Amezquita, F Farfan -- Cabrera, D Galiano -- Huasco, W Huaraca -- Silva-Espejo, J E -- Araujo-Murakami, A -- da Costa, M C -- Rocha, W -- Feldpausch, T R -- Mendoza, A L M -- da Costa, A C L -- Meir, P -- Phillips, O L -- Malhi, Y -- England -- Nature. 2015 Mar 5;519(7541):78-82. doi: 10.1038/nature14213.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK. ; Department of Physical Geography and Ecosystem Science, Lund University, Solvegatan 12, 223 62 Lund, Sweden. ; Universidad Nacional San Antonio Abad de Cusco, Apartado Postal Nro 921, Cusco, Peru ; Museo de Historia Natural Noel Kempff Mercado, Universidad Autonoma Gabriel Rene Moreno, Av. Irala 565, Casilla 2489, Santa Cruz, Bolivia. ; Universidade Federal do Para, Instituto de Geociencias, Faculdade de Meteorologia, Rua Augusto Correa, n degrees 01, CEP 66075 - 110, Belem, Para, Brazil. ; IPAM Instituto de Pesquisa Ambiental da Amazonia Rua Horizontina, 104, Centro, 78640-000 Canarana, Mato Grosso, Brazil. ; Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK. ; 1] School of Geosciences, University of Edinburgh, Edinburgh EH9 3FF, UK [2] Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia. ; School of Geography, University of Leeds, Leeds LS2 9JT, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25739631" target="_blank"〉PubMed〈/a〉
Keywords:
Brazil
;
Carbon/*metabolism
;
Carbon Dioxide/metabolism
;
Cell Respiration
;
*Droughts
;
*Forests
;
Photosynthesis
;
Trees/cytology/metabolism
;
*Tropical Climate
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
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