Modeling Sustained Delivery of Agroecosystem Services at a Watershed Scale under Climate Change

Abstract:

The intensive land use and agricultural production systems in the Chippewa River Watershed (CRW) in Minnesota, USA, contribute to inherent environmental problems and have major direct impact on soil conservation, and on several competing agro-ecosystem services (AESs); and may have indirect impact on AESs in the Upper Mississippi River Basin (UMRB). Field-scale indicators of AESs are largely absent in the highly diverse soils of the CRW. Therefore, proxy indicators were developed to assess these services under current (A0) and predicted (A2; 100 years) global climate change (GCC) scenarios. Individual indices were developed for biomass, grain yield, NO3- and NH4-N, soil carbon, runoff, and soil erosion for 132 soil series classified into three land capability classes (LCCs). The indices and a weighted index (Iw) were subjected to multivariate analyses procedures, including distance-weighted least squares, and variance components estimation. Three-D maps delineated contiguous areas of increasing or decreasing AESs in response to projected GCC. Largest significant variance portions in Iw were attributed to GCC scenarios; followed by the interaction of crop rotations and LCCs within conventional and organic cropping systems. The AES were predicted with larger certainty under A2 in organically-managed LCC-1 compared to conventional management. Significantly more runoff and soil erosion are predicted in conventionally-managed LCC-2 and LCC-3 under the same GCC scenario, regardless of soil heterogeneity. The modeling framework and the mapped AES indicators are designed to achieve multiple goals and will be used to support farmers in designing specific crop rotations that are suitable for each of the three LCCs and for major and vulnerable soil series in the watershed. Also, the modeling framework will address sustained delivery of multiple AESs, while enhancing soil conservation, water quality, and environmental protection aspects of farming in the CRW and the UMRB.