Population ecology and habitat suitability modelling of Quercus semecarpifolia Sm. in the sub-alpine ecosystem of Great Himalayan National Park, north-western Himalaya, India

Abstract

Quercus semecarpifolia Sm. is a multipurpose, ecologically and economically important tree species of the sub-alpine ecosystem in the Indian Himalayan Region, forming a major part of the forests between 2800 and 3700 m amsl. Because of various natural and anthropogenic factors, populations of several forest species are dwindling in the region. This warrants the study of the population status, regeneration pattern, physicochemical properties of soil, and habitat suitability model of Q. semecarpifolia in the sub-alpine ecosystem of the Great Himalayan National Park (GHNP). In total, 37 populations, representing 4 habitats and 8 aspects between 2803 and 3613 m amsl and with 20–65° slope, were sampled to determine the species richness, density, total basal area, Species Diversity Index (H'), Concentration of dominance (Cd), and profile of the species. Among the populations, total tree density of Q. semecarpifolia ranged from 40 to 840 Ind ha−1, with a total basal area of 0.01–122.58 m2 ha−1, total shrub density of 240–1810 Ind ha−1, total herb density of 13.8–162.3 Ind m−2, total sapling density of 10–670 Ind ha−1, and total seedling density of 10–700 Ind ha−1. H' of trees ranged from 0.03 to 1.84, that of saplings between 0 and 2.44, of seedlings between 0 and 0.36, of shrubs between 0.43 and 2.28, and of herbs between 1.07 and 3.33. Cd for trees ranged from 0.00 to 1.00, that for saplings from 0.00 to 1.00, for seedlings from 0.00 to 1.00, for shrubs from 0.43 to 2.28, and for herbs from 0.07 to 3.33. Most individuals were in the range 73.6–94.5 cm circumference at breast height, and the least were in the ranges 136.6–157.5 cm and ≥ 220.6 cm. Seedlings and saplings were relatively very high in number. Tree density showed a positive correlation with total nitrogen (p ≤ 0.01, r = 0.35, n = 37) and a negative correlation with pH (p ≤ 0.01, r = -0.13, n = 37). The MaxEnt model calibration test for Q. semecarpifolia yielded satisfactory results (AUCmean = 0.899 ± 0.02). The BIO19 (precipitation in the coldest quarter) variable was the most influential and contributed 76.7% to the habitat model. The model identified an area of 145 km2 as suitable for reintroduction of the species in the GHNP. Frequent monitoring of species populations, standardization of propagation protocol for mass multiplication, awareness among the inhabitants, and establishment in in-situ and ex-situ conditions are recommended.