Representing silvicultural management practices in SWAT and quantifying their impact on water yield
Abstract
Forests impact the dynamics of the terrestrial hydrologic cycle through their roles in evapotranspiration, interception, shading, and modification of the atmospheric boundary layer. These processes can be highly dependent on characteristics of forest stand structure (FSS), such as density, age, and species composition. FSS is rarely static, therefore its dynamics must be accounted for when assessing hydrologic impacts of forests. Silvicultural management practices inherently introduce FSS dynamics in managed forests, which are a substantial fraction of the land area in many watersheds. The hydrologic impact of stand-scale management, when widely applied, may drive substantial regional hydrologic changes. The Soil and Water Assessment Tool (SWAT) is well-suited for assessing hydrologic impacts of land management. However, since SWATs management operations are primarily designed for annual crops, it is not straightforward to simulate multi-decadal forest management practices. In this study, we implemented a range of common silvicultural practices in SWAT for pine plantations of the southeastern U.S. Specific practices were defined with forestry stakeholders in a participatory modeling process for loblolly, slash, and longleaf pine. Pine species were added to SWATs plant database and calibrated using multiple data types. Narrative stakeholder descriptions of planting density, rotation age, stand thinning, pine straw raking, and rotation staggering were translated into SWAT code using standard management operations. Practices were simulated in SWAT, and their water and production yields quantified. Production yield results closely agreed with typical forest product yields for the region, indicating SWAT can accurately simulate managed forests if properly calibrated. We also found a two-fold range in water yields across management practices, indicating their control on forest hydrology. The general approach described is not exclusive to pine plantations and can be applied to simulate other types of managed forests in SWAT.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H21I..08R