Seasonal Variation in Above-Ground Annual and Perennial Phytomass of an Arid Rangeland in Libya

Abstract

An Aristida pungens-Retama retam rangeland in the arid Jeffara plain in Libya produced 2,000 and 950 kg (dry matter) ha-1 of net above-ground phytomass with 200 mm and 171 mm of rainfall during the 1977/78 and 78/79 growing seasons, respectively. Annual plants contributed 460 and 300 kg (dry matter ha-1) in the 2 seasons, respectively. Perennial shrubs lost their 1978 winter-spring aerial production during the long 1978 summer and dry winter when grazable forage was most needed. In contrast, spring production of annual plants remained available and grazable until late summer. Settlement of shepherds' families on site is not advised as the dead standing phytomass (270 kg dry wood ha-1) may be rapidly exhausted for fuel consumption, leading to wind erosion problems on presently fixed sand dunes.