Collaborative research: Defining the scope and consequences of ectomycorrhizal fungal control on forest organic matter decomposition

真菌在森林生态系统中发挥着重要作用，分解掉在森林地面上的落叶和木质残体。 随着这些有机物被真菌分解，其中大部分被纳入土壤，增加了它们所拥有的重要碳和氮库。人们越来越认识到，与许多森林树木形成营养共生的外生菌根真菌可以减缓有机质的分解并稳定土壤碳。本研究旨在批判性地评估外生菌根真菌如何抑制有机质分解，并描述这种抑制对土壤碳和氮动态的影响。确定外生菌根真菌如何在有机质分解过程中介导碳和养分通量，将有助于森林管理，重点是土壤中的碳保持和树木健康。此外，定义在不同的温度和湿度条件下，外生菌根真菌抑制有机物分解的范围对于准确制定地球系统模型中的碳和氮动态将是重要的。该项目提供科学，技术，工程和数学（STEM）研究生和本科生指导，K-12体验式学习，并通过与雪松溪生态系统科学保护区，分钟地球，科学的加州科学院和自然历史的佛罗里达博物馆合作公众参与的支持。外生菌根真菌的能力，修改有机质分解假设取决于三个因素：有机质化学，外生菌根真菌群落组成，和环境条件。这一假设将在明尼苏达州、佛罗里达州和加州州的研究地点进行一系列实地实验来检验。通过利用一个单一的研究地点在明尼苏达州，其中广泛的有机质类型，同时部署在不同的外生菌根真菌群落组成的林分，有机质化学和外生菌根真菌群落组成的独立和互动的作用，可以确定，同时保持多个环境变量不变。同时，通过在温度和降水量不同的多个地点（明尼苏达州，佛罗里达和加州）部署一个共同的有机物类型，土壤条件的变化影响外生菌根真菌抑制有机物分解的程度也可以评估。此外，对不同土壤组分中碳的详细分析将提供外生菌根真菌引起的有机物分解率变化和土壤中碳保留之间的关键缺失环节。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Fungi play an essential role in forest ecosystems, breaking down leaf litter and woody debris that has fallen to the forest floor. As this organic matter is decomposed by fungi, much of it is incorporated into soils, adding to the significant carbon and nitrogen pools they harbor. There is growing recognition that ectomycorrhizal fungi, which form nutritional symbioses with many forest trees, can slow the breakdown of organic matter and stabilize soil carbon. This research seeks to critically assess how ectomycorrhizal fungal suppress organic matter decomposition, and to characterize the impacts of this suppression on soil carbon and nitrogen dynamics. Determining how ectomycorrhizal fungi mediate carbon and nutrient fluxes during the decomposition of organic matter will be useful for forest management focused on carbon retention in soils and on tree health. In addition, defining the scope of ectomycorrhizal fungal suppression of organic matter decomposition across diverse temperature and moisture conditions will be important for accurately formulating carbon and nitrogen dynamics in Earth system models. This project provides support for science, technology, engineering and math (STEM) graduate and undergraduate mentoring, K-12 experiential learning, and public engagement through collaborations with the Cedar Creek Ecosystem Science Reserve, Minute Earth, California Academy of Sciences, and the Florida Museum of Natural History. The capacity of ectomycorrhizal fungi to modify organic matter decomposition is hypothesized to depend on three factors: organic matter chemistry, ectomycorrhizal fungal community composition, and environmental conditions. This hypothesis will be tested with a series of field-based experiments at research sites in Minnesota, Florida, and California. By utilizing a single research site in Minnesota in which a wide range of organic matter types are concurrently deployed across forest stands differing in ectomycorrhizal fungal community composition, the independent and interactive roles of organic matter chemistry and ectomycorrhizal fungal community composition can be determined while holding multiple environmental variables constant. At the same time, by deploying a common organic matter type across multiple sites varying in temperature and precipitation (in Minnesota, Florida, and California), the extent to which variation in edaphic conditions influence ectomycorrhizal fungal suppression of organic decomposition can also be assessed. Additionally, detailed analyses of the carbon held in various soil fractions will provide a critical missing link between ectomycorrhizal fungal-induced changes in organic matter decomposition rates and retention of carbon in soil.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.