Caratteri Fondamentali della Vegetazione delle Paludi Pontine

Abstract

Observations in various microhabitats as regards the composition of different growth forms in an alpine region of Tungnath, northwestern Himalaya, were carried out. Maximum frequency was displayed by mat-forming forbs (Trachydium roylei, 100%) throughout the growing season (May–October). Maximum values for density and Importance Value Index (IVI) (452.10 plants m^?2 and 157.8, respectively) were recorded for tussock graminoids, Poa annua (L.). The IVI of different growth forms exhibited significant positive correlation with stoloniferous graminoids (KD), mat forming forbs (TR) and prostrate creeping dwarf shrubs (GT). A significant positive correlation with plant available water was also detected for mat-forming forbs (TR) and one of the plant species (CN) representing stoloniferous graminoids. The values of concentration of dominance (Cd) ranged from 0.0001 to 0.277. Diversity index (H) was highest (0.532) for tussock graminoids Danthonia cachemyriana (Jaub &; Spach.), P. annua] indicating the relative abundance of this growth form. Overall, tussock graminoids are dominant in the region, indicating stable and moderate steepness of the slopes, the major topographic feature of Tungnath. Besides topography, grazing, anthropogenic activities and interactions among associated species are the determining factors for the phytostructure of alpine communities in Himalaya.