LTREB: How does inter-annual variation in rainfall interact with soil fertility and chronic disruption of soil moisture dynamics to alter soil C cycling in tropical forests?

LTREB：降雨量的年际变化如何与土壤肥力和土壤湿度动态的长期破坏相互作用，从而改变热带森林的土壤碳循环？

• 批准号: 2332006
• 负责人: Daniela Cusack
• 金额: $ 59.83万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2029-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2332006&HistoricalAwards=false
• 关键词: LTREB; How; does; inter; annual

Many tropical forests are experiencing drying and increased variation in rainfall events. Tropical forests are among the most diverse ecosystems on Earth and hold some of the largest stocks of carbon in plants and soils globally. Thus, they are a “carbon bank,” storing carbon in solid form and reducing potential carbon in the atmosphere as the greenhouse gas carbon dioxide (CO2). Therefore, these ecosystems are important to global societies for biodiversity, nutrient cycling, and climate moderation. This project studies the effects of drying on carbon storage and cycling in tropical forests, using a long-term experiment that reduces rainfall inputs to four distinct tropical forests in Panama. The forests have different background rainfall and soil fertility, which could influence how they respond to drying. The project was established in 2015, and thus is accumulating a long-term dataset. In the initial seven years of data there was large variation in carbon fluxes and cycling from year to year, possibly related to variation in rainfall between different years. This new project, called Panama Rainforest Changes with Experimental Drying (PARCHED), will now continue for an additional 5 – 10 years of measurements. These results will help improve understanding of how tropical forest carbon storage changes over decades in response to climate variability. Undergraduate students will have opportunities to be involved in research, and there will be outreach materials produced in both English and Spanish. Results from the past seven years of the PARCHED experiment have some anomalies relative to what would be predicted. Some model predictions matched experimental results, while some mismatches suggested that important processes in tropical forests were not represented in the model. In particular, the importance of reduced water fluxes into soils, and related reductions in delivery of nutrients into soils, were lacking from the model, which could be important in the context of inter-annual variation in rainfall and soil hydrology. This project works to: a) determine whether observed chronic drying effects on tropical carbon cycling years persist over one to two decades of background rainfall variation; b) allow for detection of changes in long-term soil carbon storage in tropical forests. The project measures tree stem and root growth, soil carbon levels, and changes in carbon losses from soils via CO2 fluxes. Ongoing work aims to improve the model characterization of important processes in rainforests under drying. In conducting these scientific activities, the project trains and support a full-time field technician, involves undergraduate researchers, and will be used as part of the Smithsonian’s science outreach efforts.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.

许多热带森林正在经历干旱，降雨事件的变化增加。热带森林是地球上最多样化的生态系统之一，在全球植物和土壤中拥有一些最大的碳储量。因此，它们是一个“碳库”，以固体形式储存碳，并以温室气体二氧化碳(CO2)的形式减少大气中潜在的碳。因此，这些生态系统对全球社会的生物多样性、养分循环和气候缓和都很重要。这个项目研究了干燥对热带森林碳储存和循环的影响，使用了一个长期实验，减少了巴拿马四个不同热带森林的降雨量。这些森林的背景降雨量和土壤肥力不同，这可能会影响它们对干旱的反应。该项目于2015年建立，因此正在积累长期数据集。在最初的七年数据中，碳通量和循环在年年之间有很大的变化，可能与不同年份之间降雨量的变化有关。这个新项目名为巴拿马热带雨林变化与实验干燥(干燥期)，现在将继续进行另外5-10年的测量。这些结果将有助于更好地理解热带森林碳储量几十年来是如何随着气候变化而变化的。本科生将有机会参与研究，并将有英语和西班牙语的外展材料制作。过去七年的炎热实验的结果与预测的结果有一些反常。一些模型预测与实验结果相吻合，而一些不匹配表明热带森林中的重要过程没有在模型中表现出来。特别是，该模型缺乏减少进入土壤的水通量的重要性，以及减少向土壤输送养分的重要性，这在降雨量和土壤水文年际变化的背景下可能是重要的。该项目的工作是：(A)确定观察到的对热带碳循环年份的长期干旱影响是否持续一到二十年的背景降雨变化；(B)能够检测到热带森林土壤长期碳储存的变化。该项目测量树干和树根的生长、土壤碳水平，以及通过二氧化碳通量从土壤中损失的碳的变化。正在进行的工作旨在改进干燥情况下热带雨林中重要过程的模型特征。在进行这些科学活动时，该项目培训和支持一名全职现场技术人员，包括本科生研究人员，并将被用作史密森学会科学推广工作的一部分。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。