NSFDEB-NERC: Gigante: Quantifying and upscaling the causes and drivers of death for giant tropical trees

陆地碳汇取决于热带巨树的持久性。最大的1%的树木储存了热带森林中一半的碳，它们的死亡将这些碳释放回大气，但我们不知道是什么杀死了这些树木，因为它们的死亡很少被描述。需要一种新的采样策略来有效地监测热带巨树的生死。Gigante将结合遥感和频繁的实地调查来回答：（1）是什么杀死了巨树，它们的死亡率在空间和时间上是如何变化的？(2)巨树死亡率变化的潜在风险因素是什么？（3）巨木死亡风险如何影响泛热带碳储量？ 我们将使用多平台，高频率遥感在五个热带森林超级站点的7,500公顷的巨树死亡事件。这些数据将有助于有针对性的实地调查，使用详细的最先进的协议，以分配最近死亡的树木在一个前所未有的大规模实地研究的死亡率接近代理。我们将把这些数据与气候、地形、冠层结构和树木性状的信息结合起来，以验证树木死亡风险的机械模型。最后，将这些风险模型与森林地块和卫星激光雷达相结合，我们将评估巨树死亡的驱动因素如何预测森林动态，结构和碳储量的空间变化。地理空间关系的验证将使我们能够估计巨树死亡率对泛热带森林碳储量的贡献。

The land carbon sink depends on the persistence of giant tropical trees. The largest 1% of trees store half the carbon in tropical forests and their deaths release this carbon back to the atmosphere, but we do not know what kills these trees because their deaths are rarely described. A novel sampling strategy is needed to effectively monitor the life and death of giant tropical trees. Gigante will integrate remote sensing and frequent field surveys to answer: (1) What kills giant trees and how do their mortality rates vary over space and time? (2) What are the risk factors underlying variation in giant tree mortality rates? and (3) How does giant tree mortality risk influence pantropical carbon stocks? We will locate giant tree mortality events using multi-platform, high-frequency remote sensing of 7,500 ha across five tropical forest super sites. These data will facilitate targeted field surveys using detailed state-of-the art protocols to assign proximate agents of mortality to recently dead trees in an unprecedently large field study. We will integrate these data with information about climate, topography, canopy structure, and tree traits to validate mechanistic models of tree mortality risk. Finally, combining these risk models with forest plots and satellite LiDAR, we will evaluate how drivers of giant tree death predict spatial variation in forest dynamics, structure, and carbon storage. The validation of geospatial relationships will allow us estimate the contributions of giant tree mortality to pantropical forest carbon stocks.