IIASA Young Scientists Summer Program: Testing the Role of Microbial Mechanisms in Moisture-Induced Soil Respiration Pulses Using a Theoretical Model

Evans Sarah E, Fort Collins CO

Investigators

Abstract

The proposed work would take place at the International Institute for Applied Systems Analysis (IIASA) as part of the Young Summer Scientist Program (YSSP). During the proposed grant period (summer 2012), the participant would carry out a project on microbial ecology in collaboration with scientists at IIASA. Intellectual merit: Microbial communities control biogeochemical functions, and therefore composition (species diversity) and function (enzyme production) can constrain larger scale processes under certain conditions. Thus, descriptions of these microbial mechanisms in models have the potential to improve predictions of biogeochemical flux, and can increase our understanding of the recently emerging field of microbial community ecology. The YSSP participant proposes to use an ecosystem model developed by Christina Kaiser - that explicitly models microbial communities - to identify precipitation patterns that most strongly control microbial community structure, and describe how changes in enzyme production under drought can influence biogeochemical functions when rainfall returns. Although several recent empirical studies have described microbial community and enzyme responses to rainfall manipulations, it is unclear what controls these shifts in microbial dynamics, and whether there are generalizable patterns in these responses. In this work, she will be able to test several hypotheses about how microbial dynamics influence larger-scale functions, and validate it with field data, presenting hypotheses and mechanisms to build off of in future empirical and modeling work. Broader impacts: This work has implications for 1) improving predictions of biogeochemical cycles, and therefore predictions of climate change feedbacks and trajectories, and 2) for integrating theoretical approaches into microbial ecology. First, nitrogen and carbon compounds are emitted from the soil through processes like denitrification and decomposition. Since many of these gases are greenhouse gases, changes in the concentration of these gases in the air in turn affect climate changes, like rainfall and temperature shifts. Microbial communities control soil biogeochemical functions, but currently this biological compartment is excluded from most models attempting to predict biogeochemical dynamics. The participant?s work will use a theoretical approach to address how microbes might contribute to function, and therefore identify whether this mechanism will increase the accuracy of biogeochemical models. Second, theoretical modeling holds great potential for improving our understanding of controls on microbial community structure and function, but has been underutilized in microbial ecology thus far. Learning theoretical approaches, both in microbial ecology and in other fields, will allow the YSSP participant to share these approaches with other microbial ecologists. Following her summer abroad, the she plans to do this through day to day interactions and in workshops and trainings, both public and academic. There is currently a lot of interest in this approach, and others are eager to learn how theoretical models can be used to compliment empirical work. This exposure will therefore not only advance the career of a female scientist, but also broaden the scope of approaches used in microbial ecology to improve model predictions and better understand microbial ecology theory.