Invasion of Imperata cylindrica (L.) Beauv. by Eupatorium Species in Northern Thailand

Abstract

The pattern of invasion of native Imperata cylindrica swards by Eupatorium in the highlands of northern Thailand was studied by the technique of comparing invasion at different sites of known history. Eupatorium ground cover decreased with increasing distance from the night camp of cattle. Variations in the curves between different villages was attributed to the number of years of sustained grazing each site had undergone. A more detailed study of one area showed a high correlation (r=0.887) between mean percent Eupatorium and the number of years of grazing, but not for estimated average stocking rate at each site. The correlation coefficient between percent Eupatorium and the product of the number of years grazing and estimated average stocking rate at each site was also high (r=0.894). Some agronomic data for E. adenophorum in one area are also presented.