Alterations on flow variability due to converting hardwood forests to pine

Abstract

Flow variability is a potential indicator of land use impacts on aquatic ecosystems and a dominating factor for lotic habitats. Vegetation management effects on the stream habitat conditions must be better understood to propose forest management activities that are compatible with general ecosystem management objectives (integrity, diversity, sustainability, etc.). In our study, we used long term flow data (1936-2004) from four gauged experimental watersheds (W1, W2, W17, W18) of Coweeta Hydrologic Laboratory in US to assess the impacts of pine conversion on flow characteristics by using paired watershed experimentation. In W1, all trees and shrubs were cut and burned in 1956-57 and white pine (Pinus strobus) was planted in 1957. In W17, white pine was planted in 1956. W2 and W18 have been kept untreated as reference watersheds for W1 and W17, respectively. After analyzing long-term daily flow series with flow duration curves and frequency analyzes, we found that the timing and magnitude of 7Q flows were changed significantly due to conversion but flow variability was not affected. Overall findings revealed that pine conversion has significantly influenced some flow characteristics but stream habitat conditions were not affected potentially.