Impacts of the Integrated Management of Invasive Weeds and Litter on Slope Hydrology in Eucalyptus Plantations in Central Yunnan, Southwest China

Abstract

Background: The hydrological effects of invasive plant control in forestland have not been well studied in the past, and numerous scientific mysteries remain unsolved. The long-term suspension of the unsolved issues will unavoidably influence the sound growth and sustainable management of forest ecosystems. This study investigates the hydrological effects of controlling invasive weeds in forestland. The research aims to understand the impact of invasive weed control on soil and water loss. Methods: Conducted in Eucalyptus benthamii Maiden & Cambage plantations in Central Yunnan, SW China, which are invaded by alien weed Ageratina adenophora (Spreng.) R. M. King & H. Rob., four surface cover treatments were applied to study runoff and sediment yielding properties. The four surface cover treatments were weed harvesting and litter elimination (WH&LE), weed harvesting and litter retention (WH&LR), litter burning and weed renewal (LB&WR), and weed retention and litter retention (WR&LR). Essentially, WH&LE and LB&WR served as integrated management approaches for invasive weeds and litter, WH&LR was an independent weed control measure, and WR&LR served as a research control. Results: Runoff was significantly higher in the LB&WR plots (3.03 mm) compared to the WR&LR plots (1.48 mm) (p < 0.05). The WH&LE plots had higher runoff (2.39 mm) than the WR&LR plots (not statistically significant), while the WH&LR plots had less runoff (1.08 mm) than the WR&LR plots (not significant). Sediment yield was lower in the WH&LR plots (0.50 t/km2) than in the WR&LR plots (0.52 t/km2) (not significant), but significantly higher in the WH&LE plots (2.10 t/km2) and LB&WR plots (1.57 t/km2) than in the WR&LR plots (p < 0.05). Conclusions: Managing invasive weeds independently reduces the risk of soil and water loss, but combined management with litter can exacerbate the issue. Invasive weed control and litter management should be performed separately in slope plantations. This study provides a scientific basis for soil and water conservation, restoration and rehabilitation of plantation ecosystems.