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

Abstract

Recruitment and survival of four important broadleaved tree species (Quercus dealbata, Quercus griffithii, Rhododendron arboreum and Schima khasiana) were studied over 2 years (July 1988 to August 1990) in undisturbed, mildly disturbed and highly disturbed forest stands of a subtropical humid forest of Meghalaya, northeast India. Disturbance was the result of selective felling in 1986-87. 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 (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 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.