Smithsonian Tropical Research Institute, Balboa, Ancón, Panama.
School of Geography, University of Birmingham, Birmingham, UK.
Nat Plants. 2021 Apr;7(4):384-391. doi: 10.1038/s41477-021-00879-0. Epub 2021 Mar 29.
Tropical forests are mitigating the ongoing climate crisis by absorbing more atmospheric carbon than they emit. However, widespread increases in tree mortality rates are decreasing the ability of tropical forests to assimilate and store carbon. A relatively small number of large trees dominate the contributions of these forests to the global carbon budget, yet we know remarkably little about how these large trees die. Here, we propose a cohesive and empirically informed framework for understanding and investigating size-dependent drivers of tree mortality. This theory-based framework enables us to posit that abiotic drivers of tree mortality-particularly drought, wind and lightning-regulate tropical forest carbon cycling via their disproportionate effects on large trees. As global change is predicted to increase the pressure from abiotic drivers, the associated deaths of large trees could rapidly and lastingly reduce tropical forest biomass stocks. Focused investigations of large tree death are needed to understand how shifting drivers of mortality are restructuring carbon cycling in tropical forests.
热带雨林通过吸收大气中更多的碳来减缓当前的气候危机，其排放量超过了自身的排放量。然而，树木死亡率的普遍增加正在降低热带雨林吸收和储存碳的能力。少数大型树木在这些森林对全球碳预算的贡献中占主导地位，但我们对这些大树如何死亡知之甚少。在这里，我们提出了一个连贯的、有经验依据的框架，用于理解和研究树木死亡率与树木大小相关的驱动因素。这个基于理论的框架使我们能够假设，树木死亡率的非生物驱动因素——特别是干旱、风和闪电——通过对大树的不成比例的影响来调节热带森林的碳循环。由于预计全球变化会增加非生物驱动因素的压力，大树的相关死亡可能会迅速而持久地减少热带森林的生物量储备。需要对大树死亡进行有针对性的调查，以了解死亡驱动因素的变化如何重塑热带森林的碳循环。
