Collaborative Research: Drought Effects on Moist Tropical Forests: A Throughfall Reduction Experiment in Amazonia

随着厄尔尼诺现象变得更加频繁和严重，亚马逊流域和其他地区的热带雨林正在经历更严重的干旱。这种干旱趋势将如何影响这些物种丰富的热带生态系统？1998年，我们在热带雨林中启动了世界上第一个大规模的降雨控制实验，部分排除了亚马逊中部一公顷森林地区的降雨。我们发现树干的生长对干旱非常敏感，森林的可燃性也是如此。在接下来的五年里，我们将确定在树木开花和结果开始失败，大树开始死亡之前，这片雨林所能承受的干旱压力的程度。然后，我们将把森林从实验性干旱中释放出来，以记录森林恢复的机制和速度。已经很清楚的是，干旱对树木生长和树木死亡的影响可能在很大程度上导致大气中的二氧化碳浓度。

Tropical rainforests in the Amazon Basin and elsewhere are experiencing stronger droughts as El Nino episodes become more frequent and more severe. How will this drying trend affect these species-rich tropical ecosystems? We initiated the world's first large-scale rainfall manipulation experiment in a tropical rainforest in 1998, partially excluding rainfall from a one-hectare forest area in central Amazonia. We discovered that the growth of tree trunks is very sensitive to drought, as is forest flammability. During the next five years, we will determine the level of drought stress that this rainforest can tolerate before tree flowering and fruiting begin to fail, and large trees begin to die. We will then release the forest from experimental drought to document the mechanisms and rates of forest recovery. It is already clear that drought effects on tree growth and tree mortality may contribute substantially to the carbon dioxide concentration of the atmosphere.