Enzymes in the Environment RCN

Overview of Keynote talk (by Josh Schimel) at tonight’s RCN workshop banquet dinner 

Q: Why do we want to add microbial mechanisms to biogeochemical models?

A: Because we really think they matter!

To incorporate enzymes into models, 2 conditions are required:

1) Soil organic matter is rate limiting

2) C product pools have alternate fates!

Currently, models are not able to accurately represent both rates and magnitudes of changes in soil C dynamics!

Soil organic matter decomposition is dependent first on microbial access constraints, and secondly on then allocations. Soil C decomposition facilitated by biological factors is important to model at specific plant rhizospheres, in the soil organic horizon, and (possibly) in dead roots. Soil C decomposition modeling is not necessarily as useful with regard to fresh litter C or the mineral fraction of the soil consistent with physically protected OM.

Three common mechanistic models include 1) Functional, 2) Guild, and 3) Trait Based models.  Today, there are many tools to assess high resolution C pools (via IR and Mass spectrometry techniques) and microbial community species assemblages (via 454 pyrosequencing). From one gram of soil from a single soil core, we can identify thousands of different C structures and microbial species. However, these relationships are impossibly difficult for us to discern because nature is too complex for man to fully understand. There is much that we can learn by embracing multidisciplinary fields such as Landscape Ecology, mathematics, and biogeochemistry. The future in understanding these soil C relationships with biology is to simplify using biogeochemical models.