Improving SWAT for simulating water and carbon fluxes of forest ecosystems

Qichun Yang; Xuesong Zhang

doi:10.1016/j.scitotenv.2016.06.238

Improving SWAT for simulating water and carbon fluxes of forest ecosystems

Sci Total Environ. 2016 Nov 1:569-570:1478-1488. doi: 10.1016/j.scitotenv.2016.06.238. Epub 2016 Jul 9.

Authors

Qichun Yang¹, Xuesong Zhang²

Affiliations

¹ Joint Global Change Research Institute, Pacific Northwest National Lab, College Park, MD 20740, USA.
² Joint Global Change Research Institute, Pacific Northwest National Lab, College Park, MD 20740, USA; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, USA. Electronic address: xuesong.zhang@pnnl.gov.

PMID: 27401278
DOI: 10.1016/j.scitotenv.2016.06.238

Abstract

As a widely used watershed model for assessing impacts of anthropogenic and natural disturbances on water quantity and quality, the Soil and Water Assessment Tool (SWAT) has not been extensively tested in simulating water and carbon fluxes of forest ecosystems. Here, we examine SWAT simulations of evapotranspiration (ET), net primary productivity (NPP), net ecosystem exchange (NEE), and plant biomass at ten AmeriFlux forest sites across the U.S. We identify unrealistic radiation use efficiency (Bio_E), large leaf to biomass fraction (Bio_LEAF), and missing phosphorus supply from parent material weathering as the primary causes for the inadequate performance of the default SWAT model in simulating forest dynamics. By further revising the relevant parameters and processes, SWAT's performance is substantially improved. Based on the comparison between the improved SWAT simulations and flux tower observations, we discuss future research directions for further enhancing model parameterization and representation of water and carbon cycling for forests.

Keywords: Carbon; Forest; Parameterization; Phosphorus; Water.