STAND DYNAMICS OF Dipterocarpus zeylanicus Thw. PLANTATION AT KIRIGALA, INGIRIYA

Abstract

Attached

Thetaxon Dipterocarpus zeylanicus Thw. is an endemic tree found mainly in lowland rainforest of the south western part of Sri Lanka. The Kirigala Hora Plantation ofthe Bope Forest Beat is situated in the Ingiriya Forest Range in Kalutara District. This plantationhas been established in 1940 by the Forest Department. Attygalle P.R. in 1998 has carried out an Ecological Assessment and Management Aspectof a D. zeylanicus plantation at Kirigala, Ingiriya. The present study could be consideredas a continuation of the study conducted by Attygalle in establishing the Stand Dynamics of the taxon. The main objective of the present study was to investigatethe Stand Dynamics of D. zeylanicus and its regeneration pattern. For this purpose31 square sample plots of 25m x 25m were systematically established. Within eachof these sample plots, sapling plots of the size 5m x 5m were placed at each comer and seedlingplots of the size 2m x 2m were placed at each comer of each sapling plot. Thedbh 10 em or above and the height of each D. zeylanicus trees within each sample plot were recorded for further analysis. The numbers of saplings (dbh < 10 em and height1m or above) and seedlings (dbh < 10 em and height < 1 m) in each sapling plot and seedling plot were recorded, respectively. Since it was observed Ochlandra stridula has some influence on the regeneration patterns of the endemic D. zeylanicus the percentage cover of this taxon was also recorded within each sample plots. The number of Dipterocarpus zeylanicus trees within the study site were recorded to be 515 while the number of saplings and seedlings were recorded to be 789 and 551, respectively. The data were analyzed by one way ANa VA test of Minitab (l3.1) statistical package. The mean height of D. zeylanicus trees within the study site was 22 m while the mean dbh was 31.4 em and mean basal area was 0.1032 m2. A significance increase in height of D. zeylanicus trees and the significance reduction in D. zeylanicus seedlings were observed. The percentage cover of Ochlandra stridula within nine sample plots were recorded to be greater than 75 % and within ten sample plots 40-75 % and it was less than 40 % within twelve sample plots. D. zeylanicus trees, saplings and seedlings in the plantation has a continues reducing trend due to the invasion of Ochlandra stridula, Illicit felling and the lack of plantation management by the Forest Department. Therefore, the Kirigala Hora Plantation should be immediately brought under proper management.