STRUCTURE, COMPOSITION AND ABOVE GROUND STANDING PHYTOMASS OF SOME GRAZABLE GRASS-DOMINATED COMMUNITIES OF PAKISTAN COAST

Abstract

Herbaceous communities that emerge on the Pakistan sea coast during monsoon have high percentage of therophytes followed by chamaephytes. Besides, dominant component of grasses, legumes were invariably present in all the sites. The number of species in a stand varied with the nature of the site and its salinity status. The above ground standing phytomass varied with the species dominating the community. The communities of non-saline sites appeared to be approaching to log-normal distribution of phytomass among the species, whereas, the distribution of phytomass in saline habitats was distinctly geometric. The standing phytomass of the sites was generally low and ranged from 89.68 to 411.61 g.m-2. The communities on the basis of decreas-ing magnitude of phytomass can be arranged as: Pennisetum divisurn > Halopyrum mucronatum > Desmostachya bipinneta > Cenchrus pennisetiformis > Panicum turgidum > Dichanthium annulatum > Spo-robolus arabicus. Indigofera oblongifolia emerged as major legume with substantial phytomass in three com-munities ot which two belonged to saline habitat (Sporobolus and Desmostachya dominated communities) and one associated with non-saline soil (Dichanthium community).