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Present study reports vegetational analysis of a forest dominated byPinus roxburghii at different slopes. Competition was observed in shrub layer between Berberis aristata and Rhus parviflora, Ruhus ellipticus and Pyrus pashia, and Pyrus pashia and Berberis aristata. Community diversity, _-diversity and concentration of dominance ranged from1.31 to 2.87; 2.0 to 2.96; and 0.09 to 0.207, respectively. Community diversity was highest (2.87) on the upper slope and was directly related to the number of shrub species. The concentration of dominance followed the opposite trend of diversity index at all the slopes. [ABSTRACT FROM AUTHOR]

The vegetation pattern of a Himalayan alpine zone in Panwalikantha at 3800 m above sea level was worked out. A total of 135 species has been reported which included the herbaceous plants viz., grasses, sedges and forbs and dwarf kharsu (Quercus semicarpifolia). Normally the plants have a short life span, however a few species persist throughout the growth period (May--October). The vegetation enters senescencein October onwards. Studies made in 5 stands varying in slope, aspect and grazing pressure revealed that Danthonia cachemyriana and Poa annua were the dominant grasses while Trachydium roylei and Geum elatum were the dominant forbs in one or the other stand. Grasses were abundant on west facing steep slopes while forbs preferred the levelled land of east facing meadows. The grasses and sedges together had optimum density during August. The species distribution among the stands was 74.4--100% contagious and 14.3--28.6% random. Stand III and V hadlowest similarity index which was almost uniform among other stands.The stands having the species with a short life-span displayed more diversity for a month or two while the stands with majority of long life-span species exhibited optimum diversity in totality. The community organization is discussed in view of dominance diversity curves. [ABSTRACT FROM AUTHOR]

Hypothesis: Chitosan, naturally abundant biomaterial showed an insignificant affinity toward arsenate. The incorporation of organosilane could improve the physical and chemical properties of chitosan for the efficient removal of arsenate from aquatic environment., Experiment: The hybrid materials were obtained by grafting the natural biopolymer chitosan with 3-mercaptopropyl trimethoxysilane (CHMS) and trimethoxy-octylsilane (CHTS). The hybrid materials along with bare chitosan were characterized with SEM-EDX, FT-IR and BET specific surface area analyses and the solid materials were further employed in the efficient remediation of aqueous solutions contaminated with As(V) under batch and column reactor operations., Findings: The hybrid materials showed an extremely high percentage of As(V) removal compared to bare chitosan within a wide range of pH. As(V) was aggregated rapidly onto the solid surfaces and relatively high percent removal of As(V) was achieved in a wide range of As(V) initial concentrations. Moreover, As(V) was bound with, relatively, weaker forces and forming an 'outer sphere complexes' at the surface of solids. The presence of co-existing ions could not significantly affect the removal of As(V) from aqueous solutions. Furthermore, breakthrough data confirmed that these two hybrid materials possessed significantly high loading capacity of As(V) even under dynamic conditions., (Copyright © 2016 Elsevier Inc. All rights reserved.)