Changes in vegetation cover and soil erosion in a forest watershed on removal of weed Lantana camara in lower Shivalik region of Himalayas

Abstract

In a hilly forest watershed located in lower Shivalik region, the invasion of Lantana camara weed resulted in a drastic reduction in plant biodiversity and ground cover, thereby increasing the rate of soil erosion. In order to reduce soil erosion and restore biodiversity, Lantana was removed from four micro-watersheds (WS1, WS2, WS3, and WS5) in year 2005. The changes in soil erosion and vegetation cover area in the ground storey (grasses + small shrubs) and middle storey (shrubs) were monitored in top, middle and lower reaches of four micro watersheds during the period 2005-2010 and were compared with a pure grass watershed (WS4) located in the same watershed. Due to Lantana removal, the canopy cover of Lantana reduced from 80-90% in 2005 to 5-10% in 2009, resulting in better light penetration and improvement in ground cover vegetation of native grasses like Eulaliopsis binata, Chrysopogon fulvus, seasonal grasses, and native shrubs like Adhatoda vasica, Murraya koenigii. There was a reduction in soil loss in all the watersheds in 2010, which was found directly related to the ground cover improvement, mainly in the top reaches of microwatersheds. It is concluded that the ground vegetation cover plays a major role in soil erosion and its reduction due to of Lantana camara invasion has a direct impact on hydrological behavior of the watershed. The removal of this weed can restore ground vegetation thereby reducing soil erosion.