Quantifying Plant Mediation of Ecosystem Multifunction in Response to Fire and Warming

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。野火和温暖的温度会影响生态系统的功能，但它们的影响也可以通过植物群落来调节。例如，野火和气候变暖可能会加速土壤的分解速度，但如果植物群落产生更厚、更难以分解的叶子，这种趋势就可以减缓。生态系统受到火灾等干扰的影响，当这些干扰发生变化时，一些物种可能无法生存。该项目研究了火灾严重程度和实验变暖如何相互作用，以塑造植物性状、植物群落和多种生态系统功能，如分解和植物生产力。该项目研究了亚利桑那州黄松森林的林下植被群落。随着气候变暖，美国西部大片地区发生越来越严重的火灾，这项工作至关重要。研究结果为未来的生物多样性、生态系统功能和生态系统稳定性提供了有价值的信息。此外，该项目还培养了新一代生态系统科学科学家。该项目实施了一项温度操纵实验，模拟未来气候情景，跨越火灾严重程度梯度，包括一系列火灾严重程度。该项目提出了三个关键假设：1)相对于未经处理的控制，火灾严重程度、气候变化及其相互作用将加强非生物过滤；2)与未处理对照相比，火灾严重程度、气候变化及其相互作用会降低植物性状多样性；3)随着时间的推移，火灾严重程度和气候变化的间接、植物介导效应的相对重要性将增加，最终导致燃烧和升温地块的生态系统功能降低。通过对植物群落和生态系统功能变化进行量化，计算出生态系统功能的两个指标。最后，使用结构方程模型来回答我们的首要研究问题：随着时间的推移，林下植物群落如何调节火灾严重程度和气候变化对生态系统多功能的影响？该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Wildfire and warm temperatures affect how ecosystems function, but their impacts can also be mediated by plant communities. For example, wildfire and warming may speed up decomposition rates in the soil, but this trend can be slowed if the plant community produces leaves that are thicker and tougher to decompose. Ecosystems are shaped by disturbances like fire, and when these disturbances change, some species may be unable to survive. This project examines how fire severity and experimental warming interact to shape plant traits, plant communities, and multiple ecosystem functions such as decomposition and plant productivity. The project studies ponderosa pine forest understory communities in Arizona. This work is of critical importance as the climate warms and increasingly severe fires occur over large area of the western United States. Results from the study provide valuable information about biodiversity, ecosystem function, and ecosystem stability in the future. In addition, the project trains a new generation of scientists in ecosystem science.The project implements an experimental manipulation of temperature that mimics future climate scenarios across a fire severity gradient that encompasses a range of fire severities. The project addresses three key hypotheses: 1) Fire severity, climate alteration, and their interactions will strengthen abiotic filtering relative to untreated controls; 2) Fire severity, climate alterations, and their interactions will reduce plant trait diversity relative to untreated controls; and 3) The relative importance of indirect, plant mediated effects of fire severity and climate alterations will increase over time, ultimately leading to a reduction in ecosystem function in burned and warmed plots. Changes in the plant community and ecosystem function are quantified, and then used to calculate two metrics of ecosystem function. Finally, structural equation modelling is used to answer our overarching research question: How does the understory plant community mediate the effects of fire severity and climate change on ecosystem multifunction over time?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.