Floristic dynamics of woody species in Chir pine (Pinus roxburghii) forests along an altitudinal gradient in Himachal Pradesh.

摘要

Floristic dynamics of a community is the indicator of variation in climate, soils, habitat, and physiography of the area. A study was conducted in the zone of occurrence (800-2,200 m amsl) of chir pine (Pinus roxburghii) forests in Himachal Pradesh, India. The entire study area was grouped into the three altitudinal zones, i.e., 900-1200 m, 1201-1500 m (Shiwalik chir pine forests) and 1501-2000 m lower Himalayan chir pine forests. Majority of the tree species showed a contiguous distribution pattern, whereas shrubs showed a contiguous and random distribution. Analysis of the density-dominance interaction showed that trees mainly showed a log-normal and geometric series of distribution, while in the case of shrubs a log series was common. Results revealed the lower Himalayan chir pine forests were less diverse in respect of tree species, having Quercus leucotrichophora as the dominant species followed by Pyrus pashia, and more diverse in the case of shrubs as compared to that of the Shiwalik chir pine forest where the associated tree species were Syzygium cumini, Lannea grandis [L. coromandelica] and Myrica esculenta followed by Pyrus pashia, Mallotus philippensis and Cassia fistula. The results of this study reveal that floristic dynamics, dominance, and the distribution of woody species change with the change in aspect and altitude.