Invasion of Chromolaena odorata in the lowveld region of Swaziland and its effect on herbaceous layer productivity

Abstract

A study was conducted to investigate pattern of Chromolaena odorata invasion and its effect on grass layer in three land use systems (communal, government ranch and game reserve) and two soil classes (lithosol and raw mineral soil). Six sites (2 ha each) were selected, one on each of the two common soil classes for each land use system. The communal land had significantly lowest (p<0.05) density (465 SE ha-1) of C. odorata compared to the game reserve and there was no significant difference in total density in the two soil classes (mean = 691 SE ha-1). The greatest proportion occurred in height class of >1-1.5 m and the lowest in >0-0.5 m. Shrub (>0.5-3 m) and seedling (>0-0.5 m) densities were significantly (p<0.05) highest in the game reserve and commercial ranch, respectively. Total dry matter (DM) grass production within and outside invaded areas showed significant differences (p<0.05) in many sites. More pronounced trends of DM production were observed for the most dominant palatable species which included Urochloa mozambicensis, Panicum deustum and P. maximum. It is concluded that the invasion of C. odorata was rated to be moderate or high while past land management may be the major factor in the difference between land use systems. The effect of invasion of C. odorata on the grass layer was also severe to constitute a threat to livestock and game industries. Adaptive control strategies are therefore recommended while further work will be required to identify the causes of difference between land uses, to determine soil characteristics and overall productivity potential as affected by C. odorata invasion as well as interaction effects between biotic and abiotic factors. © 2008 Academic Journals Inc.