Tutorial: Defining which microbial properties matter most for which ecosystem process and how to measure them

Background/Question/Methods

Sequence based molecular microbial ecology has made environmental microbiology one of the most rapidly advancing fields in science today. Our understanding of the breadth and depth of functional and phylogenetic microbial diversity is increasing at a dramatic pace. The significance of microorganisms to ecosystem processes has been long been recognized and has lead to the paradigm that more information on environmental microorganisms will lead to increased understanding of ecosystem function. We posit that while microorganisms are essential to the functioning of all ecosystems, more information on environmental microbes does not map “one-to-one” into an enhanced understanding of ecosystem processes. As a result, the value of increasingly detailed characterization of environmental microbial communities has not necessarily yielded a better understanding or prediction of ecosystem processes. Although some recent studies have demonstrated that the incorporation of a set of microbial parameters can improve the performance of ecosystem models, we lack a general “rule of thumb” for when and what types of microbial data are most useful in explaining variation in biogeochemical processes. This knowledge gap defines a need to quantitatively evaluate which microbial data are best suited to improve our ability to predict ecosystem processes, and to direct future analyses toward approaches that are most likely to advance our understanding of ecosystem functioning.

Results/Conclusions

We note that the term “ecosystem process” is exceptionally vague and thus misleading in a way that makes discourse on its drivers ambiguous.  Depending on the ecosystem process of interest (e.g. N₂O flux vs. carbon storage), the scale the question being asked (e.g. diel vs. decadal), and the environmental stability of the system of interest (e.g. mean and range of annual temperature) it may or may not be useful to include explicit information on microbial community dynamics to an ecosystem level model. Multiple levels of resolution exist within the pool of potential microbial characteristics, some of which may be useful to better understand certain processes, some of which may not. By explicitly specifying the question and the system of interest, which microbial community characteristics that are likely to improve understanding can be identified a priori. This talk will serve as an introduction to the symposium and act as an overview of some of the progress that our working group has made at the John Wesley Powell Center for Ecological Analysis and Synthesis.