Simulating the Spatial Variation of Carbon Processes at a Critical Zone Observatory

Development and test of a spatially distributed land surface hydrologic biogeochemistry model with nitrogen transport.

The Science

A distributed land surface hydrologic biogeochemistry model with nitrogen transport processes is developed and tested at the Shale Hills watershed. The model is able to represent the spatial variations in terrestrial carbon processes and suggests that tree growth at the Shale Hills watershed is nitrogen limited.

The Impact

The coupled Flux-PIHM-BGC model provides an important tool to study spatial variations in terrestrial carbon and nitrogen processes and their interactions with environmental factors, and to predict the spatial structure of the responses of ecosystems to climate change.


A spatially distributed land surface hydrologic biogeochemical model with nitrogen transport, Flux-PIHM-BGC, has been developed by scientists at Pennsylvania State University by coupling a  one-dimensional (1D) mechanistic biogeochemical model, Biome-BGC (BBGC), with a spatially distributed land surface hydrologic model, Flux-PIHM, and adding an advection dominated nitrogen transport module. In the coupled Flux-PIHM-BGC model, each Flux-PIHM model grid couples a 1D BBGC model, while nitrogen is transported among model grids via surface and subsurface water flow. The coupled Flux-PIHM-BGC model has been implemented at the Susquehanna Shale Hills Critical Zone Observatory. The model-predicted aboveground vegetation carbon and soil carbon distributions generally agree with the macro patterns observed within the watershed, although the model underestimates the spatial variability. Model results suggest that the spatial pattern of aboveground carbon is controlled by the distribution of soil mineral nitrogen. A Flux-PIHM-BGC simulation without the nitrogen transport module is also executed. The model without nitrogen transport fails in predicting the spatial patterns of vegetation carbon, indicating the importance of having a nitrogen transport module in spatially distributed ecohydrologic modeling.

Principal Investigator

David Eissenstat
The Pennsylvania State University

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science


This work is supported by the Office of Biological and Environmental Research (BER), within the U.S. Department of Energy Office of Science, under Award Number DE-SC0012003, and facilitated by the National Science Foundation Critical Zone Observatory program grants to CJD (EAR 07- 25019) and SLB (EAR 12-39285 and EAR 13-31726).

Related Links


Shi, Y., D. M. Eissenstat, Y. He, Y., and D. J. Davis. "Using a spatially-distributed hydrologic biogeochemistry model with a nitrogen transport module to study the spatial variation of carbon processes in a Critical Zone Observatory". Ecological Modelling 380 8–21  ((2018)).