COMPOSITION OF HERBAGE IN THREE DIFFERENT <em>PINUS</em> <em>ROXBURGHII</em> STANDS AND AN OPEN GRASSLAND: SPECIES DIVERSITY AND DENSITY

Abstract

A study was conducted to investigate the structural differences in vegetation under three different chir pine (Pinus roxburghii) stands of three ages and an open grassland in the sub-tropical region of Himachal Pradesh in India. In all, eighteen herbage species (nine grasses, four sedges, three legumes and two non-legumes) were recorded in the four systems. Minor differences in the floristic composition of the vegetation were recorded in the four systems in the different sampling months. However, the herbage diversity and richness were higher in the open grassland as compared to the three chir pine based systems. Maximum density (tillers m^-2) of the vegetation was recorded in July and thereafter it declined gradually in the subsequent months in all the systems. Highest density was recorded in the sapling stand of the chir pine as compared to the other three systems during the period from July to September. The differences in the density of vegetation in the four systems during different sampling months and changes in the density of vegetation in the subsequent months in all the systems were statistically significant.