LTREB: A Mechanistic Understanding of Ecosystem Resilience and Recovery In Seasonally Dry Tropical Forest Experiencing Disturbance

热带森林为无数生物提供了栖息地，并通过在树木和土壤中储存大量碳来帮助保护地球气候。这些森林中有许多是次生林，在砍伐或放牧后重新生长。热带次生森林更新还没有完全被了解。这使得很难预测热带森林的特征随着时间的推移如何变化，以及它们恢复生物多样性保护和碳储存等重要功能的速度有多快。跟踪树木的出生、生长和死亡，并测量随着森林生态系统重新生长而发生的其他变化的长期研究，对于了解森林在发展过程中如何变化是必要的。该项目扩展了哥斯达黎加不同年龄和土壤类型的季节性干燥森林地块的森林更新的长期实地测量，然后利用这些见解来改进森林生长的生物现实模拟模型。这些结果有广泛的应用，从改善碳储存的恢复项目到模拟一系列气候情景下热带森林的未来状态。该项目的核心数据将用于本科生的热带生态学在线学习模块。长期数据对于了解生态系统随时间的变化至关重要。在哥斯达黎加瓜纳卡斯特的演替和土壤梯度上建立了18个林地，自2008年以来一直在进行连续测量。这些地块包括土壤特性的空间梯度和气候条件的巨大年际变异性，包括有记录以来最严重的干旱。由于2015年的极端干旱，森林地块经历了不同的死亡率，并处于不同的恢复阶段。这个项目扩展了对生物量、凋落物、树木和木本藤本植物的组成和人口学、土壤生物地球化学和果树降雨量(作为鳞翅目幼虫丰度的间接指标)等关键响应变量的测量，以测试五个假说，这些假说涉及生物和非生物对演替过程的控制，以及干旱森林对极端气候事件的抵抗力和恢复力。该项目将产生新的基本知识，了解热带干燥森林如何因土地利用和干旱的干扰而在时间和空间上发生变化，以及两个关键群体--固氮豆科树木和木本藤本植物--在调节这些过程中的作用。所有数据、模型输出和模型代码将在在线资源库中免费提供给科学界。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Tropical forests provide habitat for countless organisms and help to protect the Earth’s climate by storing large amounts of carbon in trees and soils. Many of these forests are secondary forests that have regrown after being cleared for cropping or grazing. Secondary forest regeneration in the tropics is not fully understood. This makes it difficult to predict how the characteristics of tropical forests change over time and how quickly they regain important functions like biodiversity conservation and carbon storage. Long-term studies that track the birth, growth, and death of trees and measure other changes as forest ecosystems regrow are necessary to understand how forests change as they develop. This project extends long-term field measurements of forest regeneration in plots of seasonally dry forest in Costa Rica that have different ages and soil types, and then uses these insights to improve biologically realistic simulation models of forest growth. These results have a wide range of applications, from improving restoration projects for carbon storage to simulating the future state of tropical forests under a range of climate scenarios. The core data from this project will be used in an online learning module about tropical ecology for undergraduate students.Long-term data are critical for understanding ecosystem change over time. Eighteen forest plots were established across successional and soil gradients in Guanacaste, Costa Rica, and have been measured continuously since 2008. The plots encompass spatial gradients in soil characteristics and large inter-annual variability in climatic conditions, including the strongest drought on record. Forest plots experienced variable mortality in response to the extreme drought of 2015 and are in various stages of recovery. This project extends measurements of the key response variables of biomass, litterfall, tree and woody vine composition and demography, soil biogeochemistry, and frass fall (as an indirect proxy for Lepidoptera larvae abundance) to test five hypotheses addressing biotic and abiotic controls on successional processes as well as the resistance and resilience of dry forest to extreme climate events. This project will generate new fundamental knowledge on how tropical dry forests change through time and space in response to disturbance from land use and drought as well as the roles of two key groups, nitrogen-fixing legume trees and woody vines in mediating these processes. All data, model output, and model code will be freely available to the scientific community in online repositories.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.