CARBON AND NITROGEN DYNAMICS WITH ENHANCED WIND EROSION-MODEL EVALUATION AND PREDICTION
Authors: Junran Li and Gregory S. Okin
Abstract: Most of the studies to date on wind erosion and ecosystem changes have focused on field observations and laboratory analyses. Relatively few studies have applied biogeochemical models to understanding the consequence of wind erosion in ecosystem changes. In this study, we evaluate the CENTURY model for its ability to provide predictions about the influence of wind erosion on C and N dynamics. Although this model has been extensively tested for a variety of ecosystems, different episodic events, and climate change scenarios, no study to date has incorporated wind erosion in combination with projected climate scenarios in the Chihuahuan Desert ecosystem, southern New Mexico. This study successfully parameterized the CENTURY model in these shrubby grassland ecosystems, having enhanced wind erosion encouraged by manual vegetation cover reduction. The model showed good correspondence between observed and estimated soil organic C and N prior to vegetation cover reduction, whereas empirical regression models failed to estimate satisfactory results. The results from the CENTURY simulations showed that C and N pools may be significantly changed with the alteration of plant community composition, but this is driven in the model primarily by vegetation change and not wind erosion of nutrient-rich topsoil. Without a specific submodel for erosion, current version of CENTURY may underestimate the function of wind erosion in depleting surface soil C and N. Fortunately, a newer version of CENTURY, which includes a layered erosion and deposition submodel, is expected to release in the near future.