THE ECOLOGY OF Dipterocarpus zeylanicus PLANTATION AT INGIRIYA, SRI LANKA

Abstract

The plantation forestry in Sri Lanka began in the late 19'h century. The forest coverprevailed at that time did not warrant a rapid expansion of plantations. Later, thedepletion of the forest resources compelled the Forest Department to embark onestablishing plantations. A rapid increase in plantation development was noted during the211d half of the 20'h century. The species selected for plantation establishment were mostlyexotics with few indigenous tree species.

Holmes as a silviculturist in the Forest Department initiated the studies on the growthperformance of indigenous tree species. The present Dipterocarpus zeylanicus plantational Ingiriya was one such location established by him in 1940. At present there are otherindigenous tree species also growing in association with D. zeylanicus.

A systematic sampling design was adopted for the study. The total sample area was 1.9375ha. The diameter at breast height and height of all the trees above 10 em were recorded in25mx25m plots numbering thirty-one. Seedlings and saplings in 2mx2m and 5mx5m plotswere also recorded. The number of plots in each case was 124. Important value indices forspecies. genera and families were calculated. Rank abundance curves were plotted.Endemic species in this plantation were recorded. Mean dbh, mean height, mean basalarea. and mean top height for D. zcylanicns were calculated. The diameter classdistribution of D. zcylanicus was plotted. Regression analysis was performed to observewhether any correlation exists between the dbh of D. zeylanicus against basal area of thesame and other species.

The plantation recorded 82 species. 70 genera and 37 families. Among the 916 individualstems recorded :'i2(71) was D. zeylanicus. There were 248 individuals of D. zeylanicus perha.

The paper highlights the lloristic. status of principal species, stand parameters and suggestinterventions for plantation management