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Drought impact on forest carbon dynamics and fluxes in Amazonia

机译：干旱对亚马逊地区森林碳动态和通量的影响

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摘要

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 CO_2 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), auto trophic respiration and het-erotrophic 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, autotro-phic 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.
机译：正如某些全球模式所预测的那样，在2005年和2010年，亚马逊河流域经历了两次强烈干旱，这是由于热带水文系统的变化可能与全球气候变化有关。 2005年干旱后树木死亡率增加，区域大气反演模型显示，与2011年相比，2010年整个盆地的CO_2吸收量均有下降（参考文献5）。但是，热带森林碳循环对这些干旱的反应还没有完全了解，也没有详细的现场调查。在这里，我们使用了来自整个南美的13个1公顷林地的网络中的数年数据，其中分别测量了净初级生产（NPP），自营养呼吸和异养呼吸的每个组成部分，以开发更好的机制了解2010年干旱对亚马逊森林的影响。我们发现在整个干旱期间总NPP保持恒定。但是，在干旱快要结束时，与2009年无干旱时相比，自养呼吸（尤其是根和茎）的自养呼吸显着下降，在三个最干旱的土地上自养呼吸持续下降。干旱后的一年中，总NPP保持不变，但碳的分配向冠层NPP转移，而不再是细根NPP。叶片水平和样地水平的测量均表明严重干旱抑制了光合作用。通过使用降雨数据将这些测量结果扩展到整个亚马逊流域，我们估计干旱在2010年使整个亚马逊地区的光合作用抑制了0.38毫克碳（0.23-0.53毫克碳）。总体而言，我们发现在干旱期间，树木通过减少与生长无关的自养呼吸来优先生长，而不是减少总NPP。这表明树木减少了在组织维护和防御方面的投资，这与生态进化论一致，即在没有生长的情况下树木在竞争上处于劣势。我们建议减弱的维护和国防投资可能反过来导致在我们的样地中观察到的干旱后树木死亡率增加。

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  • 来源
    《Nature》 |2015年第7541期|78-82|共5页
  • 作者

    Christopher E. Doughty; D. B. Metcalfe; C. A. J. Girardin; F. Farfan Amezquita; D. Galiano Cabrera; W. Huaraca Huasco; J. E. Silva-Espejo; A. Araujo-Murakami; M. C. da Costa; W. Rocha; T. R. Feldpausch; A. L. M. Mendoza; A. C. L. da Costa; P. Meir; O. L. Phillips; Y. Malhi;

  • 作者单位

    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;

    Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK;

    Universidad Nacional San Antonio Abad de Cusco, Apartado Postal Nro 921, Cusco, Peru;

    Universidad Nacional San Antonio Abad de Cusco, Apartado Postal Nro 921, Cusco, Peru;

    Universidad Nacional San Antonio Abad de Cusco, Apartado Postal Nro 921, Cusco, Peru;

    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, Institute de Geociencias, Faculdade de Meteorologia, Rua Augusto Correa, n 01, CEP 66075 -110, Belem, Para, Brazil;

    IPAM Institute de Pesquisa Ambiental da Amazonia Rua Horizontina, 104, Centra, 78640-000 Canarana, Mato Grosso, Brazil;

    Department of Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK;

    Universidad Nacional San Antonio Abad de Cusco, Apartado Postal Nro 921, Cusco, Peru;

    Universidade Federal do Para, Institute de Geociencias, Faculdade de Meteorologia, Rua Augusto Correa, n 01, CEP 66075 -110, Belem, Para, Brazil;

    School of Geosciences, University of Edinburgh, Edinburgh EH9 3FF, UK,Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia;

    School of Geography, University of Leeds, Leeds LS2 9JT, UK;

    Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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