Dynamics of tree seedling populations in a humid subtropical forest of northeast India as related to disturbance

Abstract

Recruitment and survival of four important broad-leaved tree species, viz Quercusdealbata L., Quercusgriffithii Hk., Rhododendronarboreum Sm., and Schimakhasiana Dyer., were studied over 2 years in the undisturbed, mildly disturbed and highly disturbed forest stands of a subtropical humid forest of Meghalaya, northeast India. Recruitment of S. khasiana seedlings was maximum in the highly disturbed stand, while Q. dealbata seedlings were abundant in the undisturbed and mildly disturbed stands. Seedlings of Q. dealbata, Q. griffithii, and R. arboreum were equally successful in all the stands, while S. khasiana seedlings showed better survival in the highly disturbed stand than in the mildly disturbed and undisturbed stands. Six microenvironmental factors, viz photosynthetically active radiation, relative humidity, air temperature, soil temperature, soil moisture, and thickness of litter on the forest floor, were correlated with the age-specific mortality rate of seedlings. In Q. dealbata, Q. griffithii, and S. khasiana, mortality rate was significantly affected by microenvironmental factors, while in R. arboreum mortality was not correlated with any of the microenvironmental factors. On the basis of seedling recruitment and survival pattern, it was concluded that Q. dealbata, Q. griffithii, and R. arboreum were successful in both disturbed and undisturbed forest stands, while S. khasiana seedlings showed better survival and establishment in the disturbed stands.