Collaborative Research: Microbial Communities as Biochemical Inputs to Forest Soil Humification Processes

土壤有机质（SOM）的形成，腐殖质化，包含了一系列复杂的生化过程。虽然已知微生物参与腐殖质化，但关于微生物如何调节植物物质向腐殖质转化的信息很少。土壤微生物对腐殖质化的一个经常被忽视的影响是，它们的身体或生物量是腐殖质物质的主要组成部分。由于不同生态系统中微生物群落的生化组成和活性存在很大差异，我们假设土壤微生物群落组成影响腐殖质化的速率以及腐殖质形成的数量和稳定性。确定微生物群落组成的作用将增强我们对SOM形成的概念理解，这是可靠预测森林生态系统碳动态的重要一步。C在微生物体中的命运将从从温带和热带森林土壤中分离出来的四种不同的真菌和细菌群开始。微生物群（完整的，死细胞）将被生物化学特征化，然后相互应用于两种土壤，以比较两种不同森林生态系统中SOM的形成过程。微生物凋落物的命运将被跟踪三年，以确定哪种微生物组形成最多和最稳定的SOM。本研究将确定微生物对腐殖化的控制，这对可持续森林生产和包括全球变暖在内的环境问题至关重要。这些结果将确定影响腐殖化过程及其产物的微生物群落的关键特征，从而大大增加我们对C储存机制的理解。

The formation of soil organic matter (SOM), humification, encompasses a complex suite of biochemical processes. While microorganisms are known to be involved in humification, little information exists on how microbes regulate the conversion of plant material into humic substances. An often-overlooked influence of soil microorganisms on humification is that their bodies, or biomass, are primary building blocks of humic substances. Since microbial communities can differ substantially in their biochemical composition and activity across ecosystems, we hypothesize that soil microbial community composition influences rates of humification and the amount and stability of humic substances formed. Defining the role of microbial community composition will enhance our conceptual understanding of SOM formation, an important step in reliably predicting C dynamics in forest ecosystems. The fate of C in microbial bodies will be followed from four distinct fungal and bacterial groups isolated from a temperate and a tropical forest soil. The microbial groups (whole, dead cells) will be biochemically characterized, then reciprocally applied to each of the two soils to compare the SOM formation processes in two dissimilar forest ecosystems. The fate of microbial litter will be tracked for three years to determine which microbial group(s) forms the greatest amount and most stable SOM. This research will define the microbial controls on humification that are critical to sustainable forest production and environmental issues including global warming. The results will identify key characteristics of the microbial community that influence humification processes and its products, thereby substantially increasing our understanding of the mechanisms involved in C storage.