EAGER: Vertebrate mortality and decomposition hot spots: soil microbial community dynamics and nutrient cycling.

动物的寿命有限，死亡在陆地生态系统中很常见。在自然界中，动物死后身体会发生什么变化？从生态学的角度来看，分解的动物会产生一个富含营养的有机物的局部脉冲（热点），使下面的土壤肥沃。动物死亡后，可以用来自动物微生物组的微生物接种环境。 人们对这些营养物质和微生物的最终命运知之甚少--有多少被保留在土壤中，被回收利用，或者被释放到大气中？这些问题对于理解生态系统中营养物质是如何产生和消耗的，以及在大规模死亡后评估腐肉输入的重要性都很重要。本研究的重点是确定动物尸体分解对土壤中氮（N）水平的影响。 因此，这项研究将有助于我们了解陆地养分通量，并通过纳入尸体来源的投入，为现有模型提供信息或扩大现有模型。 这项研究将提供有关自然分解过程以及营养物质循环的非生物和生物控制的基础知识。 这一知识在农业（牲畜死亡处理）和法医学（估计死亡时间）方面具有潜在的应用价值。 该项目还将为博士后学者提供微生物生态学，土壤地球化学，法医人类学，分子生物学和生物信息学的跨学科培训，并将支持和本科生实习生和田纳西州4-H计划的土壤和环境科学新课程的开发。 初步研究表明，分解尸体下方土壤中的微生物群落包括原生土壤分类群和从尸体或访问尸体的昆虫引入的分类群。 这些群落的组成和功能都发生了变化，随着时间的推移，它们会转向更厌氧的代谢策略。 本研究的目的是确定N在尸体分解热点的命运，并阐明非生物（温度和氧气）和生物（分解者群落组成）因素如何控制N的命运。 这一目标将通过实验室围隔生态系统和现场尸体分解实验相结合来实现，操纵非生物和生物控制，并记录对氮库（硝酸盐，氨，一氧化二氮）和通量（硝化和反硝化速率）的影响。 分解微生物群落将使用N循环基因的功能基因表达和测序进行检查。 这将揭示参与分解的微生物类型以及它们转化营养物质的机制。最终，这项研究将提供陆地生态系统中脊椎动物营养物质死后命运的理解。

Animals have limited life spans, and mortality is a common occurrence in terrestrial ecosystems. What happens in nature to the body of an animal after it dies? From an ecological perspective, a decomposing animal creates a localized pulse (hot spot) of nutrient-rich organic matter, fertilizing the soil below. Following death of an animal, the environment may be inoculated with microorganisms from the animal's microbiome. Very little is understood about the ultimate fate of these nutrients and microbes - how much is retained in soil, recycled, or released into the atmosphere? These questions are important in terms of understanding how nutrients are produced and consumed in ecosystems, and evaluating the importance of carrion inputs across larger scales, following massive die-offs, for example. The focus of this study will be to determine the impact of decomposing animal carcasses on nitrogen (N) levels in soil. As a result, this research will contribute to our understanding of terrestrial nutrient fluxes, and will inform or expand existing models through the inclusion of carcass-derived inputs. This research will provide foundational knowledge about a natural decomposition process and the abiotic and biotic controls on nutrient recycling. This knowledge has potential applications for agriculture (livestock mortality disposal) and forensic science (time since death estimations). This project will also provide interdisciplinary training for a postdoctoral scholar in microbial ecology, soil biogeochemistry, forensic anthropology, molecular biology, and bioinformatics and will support and undergraduate trainee and the development of new curriculum on soil and environmental science for Tennessee 4-H programs.This research will provide a comprehensive evaluation of N flux in carcass decomposition hotpots. Preliminary research shows that microbial communities in soils below a decomposing carcass include both native soil taxa and introduced taxa from the carcass or insects that visit the carcass. These communities change in both composition and function, shifting to more anaerobic metabolic strategies over time. The objective of this research is to determine the fate of N in carcass decomposition hotspots, and elucidate how abiotic (temperature and oxygen) and biotic (decomposer community composition) factors control the fate of N. The objective will be met using a combination of lab mesocosms and field decomposition experiments with carcasses, manipulating abiotic and biotic controls and documenting the effects on N pools (nitrate, ammonia, nitrous oxide) and fluxes (nitrification and denitrification rates). Decomposer microbial communities will be examined using functional gene expression of N cycling genes and sequencing. This will reveal the types of microbes involved in decomposition and the mechanisms by which they are transforming nutrients. Ultimately this research will provide an understanding of the postmortem fate of vertebrate nutrients in terrestrial ecosystems.