STUDY OF GROWTH PATTERN AND PHENOLOGY OF Dipterocarpus zeylanicus FROM TWO FOREST RESERVES OF SRI LANKA

Abstract

Dipterocarpus zeylanicus is an endemic emergent tree which grows in the wet evergreenforests of Sri Lanka. Usually it grows up to height of about 45 rn , A study of the growthpattern and phenology was carried out at two forests reserves viz. Konawa Forest Reservelocated in the wet zone and Ellakanda forest reserve located in the intermediate zone of SriLanka. Both zones receive rain through the year but the intensities of rainfall receivedduring the North Eastern (NE) and South Western (SW) monsoons in the two zones aredifferent. SW being the most prominent in the wet zone of Sri Lanka and NW monsoon isequally intense as SW in the intermediate zone. Monthly growth increments were studiedusing dcndromcter bands and phenological events were observed monthly. The growthintensity varied during the year, though there was a least some growth throughout the year.There was higher growth with an average diameter increment of about 3 mrn/ month in thetrees growing in the intermediate zone while in the wet zone, the average was around 1mrn. In the wet zone higher growth was recorded during the SW monsoonal period (i.e.From May to July) whereas growth of equal intensities was recorded during SW and NE(i.c. From October to December) monsoons in the intermediate zone. For phenologicalobservations, period of leaf growth / greening, leaf fall, flowering, seed ripening / fruiting,and number of growth periods were recorded.