FRUTING PHENOLOGY OF EIGHT Shorea SPECIES IN SINHARAJA MAN AND BIOSPHERE RESERVE

Abstract

The canopy of Sinharaja rain forest is dominated by Mesua and Shorea spp., which areendemic to Sri Lanka. Information on the fruiting phenology of Shorea is vital, in termsof identifying trees as mother trees and collecting seeds for restoration and reforestationof degraded forest areas in the south-western part of Sri Lanka

The phenology of eight Shorea species, [SO affinis, S. congestiflora, S. trapezifolia and S.zeyJanica belonging to the Thiniya group and S. cordifolia, S. megistophyJ/a, S.worthingtonii and S. disticha belonging to the Beraliya group] were examined foreighteen years. Fruiting of selected individuals was recorded fort-nightly as a percentageof the observable part of the crown in flower. The effect of environmental parameters onfruiting was assessed using Spearman rank correlation coefficient.

In all species, the number of trees participating in a given fruiting event differed greatlybetween years. Individuals of S. trapezifolia and S. zeyJanica had more intense fruitingactivity (>50%) in most years while, it was only 1-50% in S. congestiflora. Fruitingintensities of individuals of the Beraliya group varied relatively little among differentfruiting episodes. An annual fruiting pattern among the Thiniyas and a supra-annualpattern in the Beraliyas were observed. The number of flowering episodes per tree washigh in members of the Thiniya group. Fruit fall was tightly synchronized among theBeraliyas, but sequential among the Thiniyas.

The monthly rainfall and the fruiting intensities of all Shorea species, except in S.cordifolia and S. zeyJanica, were significant. The seasonal rainfall and fruitingintensities of four Shorea species were significantly correlated. The timing and intensityof fruitingwas observed to coincide with favorable environmental conditions.

This project was funded by grants from by the USAID (Grant No: DPE-5542-G-55-4073-00) through Harvard University, U. S. A. and the John D. and Catherine T.MacArthur Foundation and the Britin Scholarship Fund