Resource availability and disturbance shape maximum tree height across the Amazon
Resource availability and disturbance shape maximum tree height across the Amazon
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DOI：
10.1101/2020.05.15.097683
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发表时间：
2020-05
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通讯作者：
E. Gorgens;M. Nunes;Tobias Jackson;D. Coomes;M. Keller;C. R. Reis;R. Valbuena;J. Rosette;D. R. D. de Almeida-D.-R.-D.-de-Almeida-29769378;B. Gimenez;R. Cantinho;Alline Zagnolli Motta;Mauro Assis;Francisca Rocha de Souza Pereira;Gustavo C. Spanner;N. Higuchi;J. Ometto
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作者：
E. Gorgens;M. Nunes;Tobias Jackson;D. Coomes;M. Keller;C. R. Reis;R. Valbuena;J. Rosette;D. R. D. de Almeida-D.-R.-D.-de-Almeida-29769378;B. Gimenez;R. Cantinho;Alline Zagnolli Motta;Mauro Assis;Francisca Rocha de Souza Pereira;Gustavo C. Spanner;N. Higuchi;J. Ometto
尽管热带巨树是进化生物学和生态系统地球化学之间的重要联系，但对影响热带巨树分布的因素知之甚少。最近在亚马逊雨林的圭亚那地盾地区发现了80米高的树木集群，这对目前对控制巨树生长和生存的因素的理解提出了挑战。这一新发现让我们重新思考这个问题：是什么决定了亚马逊最高树木的分布？在这里，我们使用高分辨率的机载激光雷达（光探测和测距）测量了整个巴西亚马逊地区282，750公顷原始古老森林和次生林的树冠高度，以调查巨型树木的发生与影响其生长和生存的环境因素之间的关系。我们的研究结果表明，控制树木生长高度的因素与控制其寿命的因素不同。树木生长在土壤粘土含量高（> 42%），辐射（每年< 130个晴天）和风速较低的地区，避免冲积区（海拔高于40米），最佳降水量范围为1，500至2，500毫米。然后，我们使用包络模型来确定支持最高树木（即超过70米高）的环境条件。我们发现，与控制大规模最大高度的无数相互作用的因素相反，风速对这些哨兵树的分布影响最大，并解释了在巴西亚马逊森林中发现70米以上树木的概率的67%。高分辨率的泛亚马逊激光雷达数据显示，推动身高增长的环境变量与支持其生存的环境变量有着根本的不同。虽然降水和温度对它们生存的重要性似乎低于以前的研究，但风和辐射状况的变化可能会重塑我们的森林生物群落。决策者在确定保护亚马逊生物多样性的重要热点时应认真考虑这一点。
The factors shaping the distribution of giant tropical trees are poorly understood, despite its importance as a link between evolutionary biology and ecosystem biogeochemistry. The recent discovery of clusters of trees over 80 metres tall in the Guiana Shield region of the Amazon rainforest challenges the current understanding of the factors controlling the growth and survival of giant trees. The new discovery led us to revisit the question: what determines the distribution of the tallest trees of the Amazon? Here, we used high-resolution airborne LiDAR (Light Detection and Ranging) surveys to measure canopy height across 282,750 ha of primary old-growth and secondary forests throughout the entire Brazilian Amazon to investigate the relationship between the occurrence of giant trees and the environmental factors that influence their growth and survival. Our results suggest that the factors controlling where trees grow extremely tall are distinct from those controlling their longevity. Trees grow taller in areas with high soil clay content (> 42%), lower radiation (< 130 clear days per year) and wind speeds, avoiding alluvial areas (elevations higher than 40 m a.s.l), and with an optimal precipitation range of 1,500 to 2,500 mm yr-1. We then used an envelope model to determine the environmental conditions that support the very tallest trees (i.e. over 70 m height). We found that, as opposed to the myriad of interacting factors that control the maximum height at a large scale, wind speed had by far the largest influence on the distribution of these sentinel trees, and explained 67% of the probability of finding trees over 70 m in the Brazilian Amazon forest. The high-resolution pan-Amazon LiDAR data showed that environmental variables that drive growth in height are fundamentally different from environmental variables that support their survival. While precipitation and temperature seem to have lower importance for their survival than expected from previous studies, changes in wind and radiation regimes could reshape our forested biomes. This should be carefully considered by policy-makers when identifying important hotspots for the conservation of biodiversity in the Amazon.