Imperata cylindrica in the Highlands of Northern Thailand: Its Productivity and Status as a Weed

Abstract

The grasslands of Northern Thailand are a consequence of shifting cultivation practices of local opium-growing farmers and they are maintained by annual fires. Their productivity is low and they are a fire hazard in the dry season. In swiddening systems, a grassland fallow appears inferior to forest as a means of restoring soil fertility after a cropping phase. Imperata cylindrica cannot be classed as a serious weed in this area; the grass provides some forage for village cattle, is seldom a problem in cultivated fields, and tends to decline or disappear if continually grazed by cattle. Improved pastures based on Desmodium intortum or Stylosanthes guianensis can readily be established and subsequently dominate other species. Data are presented of an experiment in which cattle were put into stands of Eucalyptus and Pinus at a stocking rate of 0.5 beasts ha'1. Damage to the trees was negligible and the cattle controlled Imperata regrowth without affecting either survival rates or the height of the trees.