Phytodiversity and growth form in relation to altitudinal gradient in the Central Himalayan (Kumaun) region of India

Abstract

In this study, we examined plant species richness at altitudes between 200 and 5800 m asl, considering altitudinal gradients (200 and 1000 m asl altitudinal differences) in the Indian Central Himalaya. The low elevation appears to be drier than higher, although precipitation varies inconsistently with elevation. Low temperature and greater cloudiness at higher elevations might increase precipitation. In this study, a total of 2487 species were recorded, of which 276 were trees, 355 shrubs, 112 climbers and 1744 herbs. The deciduous trees were maximum at 600 –800 m asl elevation and evergreen trees were maximum at 1200 –1400 m elevation. Shrub species occurred in the altitude range of < 200 to 4800 m asl. The total number of shrub species varied from 2 (4600 m asl) to 35 (1400 m asl). The total number of climber species was maximum at an altitudinal range of 800 –100 m asl for deciduous as well as evergreen species. Along the altitude, the geographic and climatic conditions change sharply. The total number of species, including all growth forms was maximum near low altitude to mid altitude of tropical/subtropical belt due to overlapping of climatic conditions, but with further increase in altitude it decreased consistently, probably due to decrease in atmospheric temperature with increase in altitude. The number of deciduous species was relatively more than evergreen species irrespective of the plant form, i.e. trees, shrubs, and climbers, which may be due to spatial fluctuation in climatic conditions. The study concludes that the distribution and species richness pattern in this region largely depend on the alt itude and climatic variables like rainfall, temper ature.