Collaborative Research: Role of soil microbiome resilience in ecosystem recovery following severe wildfire

野火是健康森林生态系统的自然特征。之所以令人担忧，是因为随着气候变暖，这些事件的频率和强度都在增加。在其众多影响中，野火干扰影响了森林土壤中存在的微生物，这些微生物催化了一系列关键的生态系统过程，从树苗的建立到碳和氮的循环。到目前为止的研究表明，野火会改变土壤微生物群落的组成，但对于美国西部森林日益严重的野火将如何影响土壤微生物群落的恢复，以及对森林生态系统的连锁影响，缺乏关键信息。这项研究使用了科罗拉多州北部一片小松林中一系列独特的燃烧堆疤痕，作为严重野火后土壤环境十年来恢复的代表。这项工作将使用不同的微生物和地球化学分析来确定火灾发生后长达50年的土壤化学和微生物群落的变化。在此获得的见解将有助于美国西部严重野火后的森林管理，并将被纳入参与研究机构的新教育机会中。该项目将丰富研究人员教授的各种课程，包括为本科生和研究生提供培训机会，并为森林管理者提供合作推广以及公共宣传活动。人们越来越认识到，野火制度的变化可能会导致地上和地下生态系统结构的长期变化。这项研究将调查松林在严重野火后土壤微生物群落的弹性(即它们恢复到火灾前水平的能力)，(2)微生物群落结构变化的功能意义，以及(3)改变的土壤微生物群落通过根际相互作用支持树木更新的能力。总之，这项研究将检验这一假说，即在严重的野火发生后，土壤化学和物理性质的改变将使土壤微生物群进入交替的稳定状态，并对建立新的松树苗木和随后的生态系统恢复产生影响。为了验证这一点，这项工作利用了一个独特的实验机会，包括整个森林生态系统中燃烧堆积的伤疤，从而确保燃料类型和负载、海拔、气候和坡向的时序控制。此外，该方法集成了不同的分析工具，包括土壤微生物群的元基因组学询问、土壤化学的质谱学表征和植被操纵温室实验。总而言之，我们的结果将是对火灾后50年恢复期内被烧毁土壤微生物的弹性程度，以及小松幼苗招募有助于树木重建的有益根际群落的能力的首次洞察。这一奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfire is a natural feature of healthy forest ecosystems. There is concern because the frequency and intensity of these events are increasing as our climate warms. Among their many impacts, wildfire disturbances impact the microorganisms present in forest soils that catalyze a series of key ecosystem processes, ranging from the establishment of tree seedlings to the cycling of carbon and nitrogen. Research to date has revealed that the composition of soil microbiomes is altered by wildfire, but critical information is lacking on how increasingly severe wildfires in western US forests will affect the recovery of soil microbial communities, with cascading impacts on forest ecosystems. This research uses a unique series of burn pile scars in a lodgepole pine forest in northern Colorado as a proxy for the decadal recovery of the soil environment following severe wildfire. The work will use diverse microbiological and geochemical analyses to determine how soil chemistry and microbiomes change up to 50-years following fire. Insights gained here will assist with forest management following severe wildfire in the western US and will be incorporated into new educational opportunities at the participating research institutions. The project will enrich a variety of courses taught by the researchers, include training opportunities for undergraduate and graduate students, and provide cooperative extension to forest managers as well as public outreach activities.There is an increasing appreciation that changing wildfire regimes may drive long-term alterations in both above- and below-ground ecosystem structure. This research will investigate the resilience of soil microbiomes (i.e., their ability to return to pre-fire levels) following severe wildfire in lodgepole pine forests, (2) the functional implications of shifts in microbiome structure, and (3) the ability of altered soil microbiomes to support tree regeneration via rhizosphere interactions. Together, this research will test the hypothesis that altered soil chemical and physical properties drive the soil microbiome to an alternate steady state following severe wildfire, with implications for the establishment of new pine seedlings and subsequent ecosystem recovery. To test this, the work leverages a unique experimental opportunity consisting of burn pile scars throughout a forest ecosystem, thus ensuring that the chrono-sequence controls for fuel type and load, elevation, climate, and aspect. Furthermore, the approach integrates diverse analytical tools including metagenomic interrogations of soil microbiomes, mass-spectrometry characterization of soil chemistry, and vegetation manipulation greenhouse experiments. Together, our results will represent the first insights into the extent of resilience of burned soil microbiomes across a 50-year post-fire recovery period, and the ability of lodgepole pine seedlings to recruit beneficial rhizosphere communities that aid in tree re-establishment.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.