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

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。野火和温暖的温度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，野火和变暖可能会加快土壤的分解速度，但如果植物群落生产出更厚、更难分解的叶子，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。这个项目研究了火灾严重程度和实验变暖如何相互作用来塑造植物特征、植物群落和多种生态系统功能，如分解和植物生产力。该项目研究亚利桑那州的黄松林林下群落。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。研究结果提供了关于生物多样性、生态系统功能和未来生态系统稳定性的有价值的信息。此外，该项目还培训了新一代生态系统科学科学家。该项目对温度进行了实验性的操纵，模拟了火灾严重程度梯度上的未来气候情景，该梯度涵盖了一系列火灾严重程度。该项目提出了三个关键假设：1)与未经处理的对照相比，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)相对于未处理的对照，火灾严重程度、气候变化及其相互作用将减少植物特征多样性；以及3)火灾严重程度和气候变化的间接植物中介效应的相对重要性将随着时间的推移而增加，最终导致烧毁和变暖地块的生态系统功能下降。对植物群落的变化和生态系统功能的变化进行了量化，并用来计算生态系统功能的两个指标。最后，结构方程模型被用来回答我们的首要研究问题：林下植物群落如何随着时间的推移调节火灾严重程度和气候变化对生态系统多功能的影响？这一奖项反映了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。

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.