Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates of deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia’s GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. Our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.

全球各地森林流失热点区域的森林丧失，不仅会对流失发生地的局地气候造成影响，还会通过生态气候遥相关（ecoclimate teleconnections）对全球偏远区域的气候与植被产生作用。这类远程影响的强度与作用机制，大概率取决于森林流失热点区域的位置与分布格局，但目前尚未有研究对这类依存关系的本质展开探讨。本研究借助全球气候模式模拟，估算了两处热点区域森林丧失所引发的、与生态密切相关的气候变化分布：一是正经历加速森林枯死的北美西部（western North America, wNA），二是正遭受高强度森林砍伐的亚马孙流域。当两处区域同时发生森林丧失时，其所产生的远程气候与生态净效应，与分别模拟两处区域森林流失后的总效应存在显著差异，这一点在三处受影响区域中均有体现：南美东部的总初级生产力（Gross Primary Productivity, GPP）之所以提升，是因为亚马孙森林丧失引发的季节降水变化，以及北美西部森林丧失带来的气温变化共同作用的结果；欧亚大陆的总初级生产力则因北美西部森林丧失导致的气温下降、土壤冰量增加而出现下降；北美东南部的植被生产力在两处区域同时发生森林丧失时有所提升，但仅在北美西部森林丧失的情况下则会下降，这源于水汽压亏缺（Vapor Pressure Deficit, VPD）的变化。本研究结果表明，我们亟需开展新一代从局地到全球尺度的分析工作，以识别潜在的生态气候遥相关、其背后的作用机制，而最为关键的是厘清它们之间的协同交互关系，从而预测未来土地利用变化与气候变化背景下，森林丧失加剧所引发的生态气候响应。