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Title: Soil enzymes as indicators of soil function: A step toward greater realism in microbial ecological modeling

Journal Article · · Global Change Biology
DOI: https://doi.org/10.1111/gcb.16036 · OSTI ID:1961811

Soil carbon (C) and nitrogen (N) cycles and their complex responses to environmental changes have received increasing attention. However, large uncertainties in model predictions remain, partially due to the lack of explicit representation and parameterization of microbial processes. One great challenge is to effectively integrate rich microbial functional traits into ecosystem modeling for better predictions. Here, using soil enzymes as indicators of soil function, we developed a competitive dynamic enzyme allocation scheme and detailed enzyme-mediated soil inorganic N processes in the Microbial-ENzyme Decomposition (MEND) model. We conducted a rigorous calibration and validation of MEND with diverse soil C-N fluxes, microbial C:N ratios, and functional gene abundances from a 12-year CO2  × N grassland experiment (BioCON) in Minnesota, USA. In addition to accurately simulating soil CO2 fluxes and multiple N variables, the model correctly predicted microbial C:N ratios and their negative response to enriched N supply. Model validation further showed that, compared to the changes in simulated enzyme concentrations and decomposition rates, the changes in simulated activities of eight C-N-associated enzymes were better explained by the measured gene abundances in responses to elevated atmospheric CO2 concentration. In conclusion, our results demonstrated that using enzymes as indicators of soil function and validating model predictions with functional gene abundances in ecosystem modeling can provide a basis for testing hypotheses about microbially mediated biogeochemical processes in response to environmental changes. Further development and applications of the modeling framework presented here will enable microbial ecologists to address ecosystem-level questions beyond empirical observations, toward more predictive understanding, an ultimate goal of microbial ecology.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER); USDA; National Science Foundation (NSF); National Science Foundation of China (NSFC); Second Tibetan Plateau Scientific Expedition and Research (STEP) Program
Grant/Contract Number:
AC02-05CH11231; FG02-96ER62291; SC0004601; SC0010715; SC0014079; SC0016247; SC0020163
OSTI ID:
1961811
Journal Information:
Global Change Biology, Journal Name: Global Change Biology Journal Issue: 5 Vol. 28; ISSN 1354-1013
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

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