Understanding the impact of micro-organisms in ecosystem dynamics

Understanding the impact of micro-organisms in ecosystem dynamics

Abstract:

Understanding the impact of micro-organisms in ecosystem dynamics: Linking multi-scale, multi-phase, and multi-process systems with microbial biomass function and dynamics in environmental modelingAlthough environmental modeling has achieved important results in predicting the dynamics of natural ecosystems, several aspects related to biota dynamics are still unresolved. Among the biota, micro-organisms have substantial effects in determining ecosystem function and its response to forcing. The overarching question that frames this work is: how can we take into account in our environmental models that micro-organisms have macro-effects? Micro-organisms largely affect the energy and mass transfer by means of highly non-linear feedback mechanisms that occur over a broad range of spatial and temporal scales.

These mechanisms imply a close coupling between aspects of physics, chemistry, and biology that requires a reshaping of the classic approach to environmental modeling. The work presented here focuses on the integration of microbial biomass dynamics and function in models used in environmental engineering. Two geophysical systems, i.e., aquatic and terrestrial, are used to show the role played by micro-organisms in determining the ecosystem response. In the first instance (the aquatic ecosystem) the dynamics of aggregation and breakup processes among fine mineral particles is coupled with the dynamics of aggregate-attached micro-organisms. In the second instance (the terrestrial ecosystem), a multi-phase and multi-component reactive flow transport model describing soil ecosystems is linked to micro-organism dynamics to highlight the effect of biomass on water flow, chemical kinetics, nutrient cycling, and contaminant release to the broader environment. A comparison with experimental data from the two ecosystems under investigation and the analysis proposed with our models suggest that the overall role of micro-organisms is more important than expected. The incorporation of a mechanistic description of micro-organism dynamics and function will allow us to improve our understanding of the environment complexity, dynamics, and response to natural and human perturbation.