A CORRELATION STUDY OF DENDROMETER BAND DATA AND PHENOLOGICAL EVENTS
WITH DIRECT TREE RING WIDTH MEASUREMENTS IN SOME TROPICAL TREES OF SRI
M P de Silva and W W Senarath
University of Ruhuna
Dendrometers provide an easy and a reliable method of detecting growth
patterns of trees by measuring changes in the diameters of tree trunks.
A total of 163 trees were used in this study selected from 15 forest stations
in the lowlands of Sri Lanka. In addition to the increase in circumference
at breast height, other phenological events such as periods of leaf growth/
greening, flowering, seed ripening and fruiting were observed. The measured
diameter increments were used for calculation of the number of growth
periods as well as to calculate the periods of highest growth and their
relationships with the observed phenological events. A correlation study
was carried out with observed ring width measurements in tree cores obtained
using a Swedish increment borer and wood slices. An important feature
that emerged from this study was the similarities and differences among
growth periods in the different tree species investigated as well as the
differences in the duration of the growth periods.
For example in the case of Swietenia macrophylla and Dipterocarpus spp
the growth periods extended throughout the year with only a few months
of less vigorous growth, whereas in trees such as Macaranga digyana, the
growth period was confined to only a few months of the year. Trees such
as Palaquium rubiginosum and Tectona grandis showed only one prominent
growth period for the year while most other tree species showed 2-3 growth
periods. In Horsfieldia irya the maximum growth period corresponded with
the period of initiation of flowering whereas in almost all tree species,
the minimum growth corresponded with phenological events such as flowering.
Trees within different climatic regimes such as thick dense forest and
open woodlands responded differently.
It can be confidently assumed in tree-ring chronology the observed phenological
events are important in growth patterns and give important hints with
reference to ring numbers in trees under tropical conditions which observations
are substantiated in this study through direct ring width and ring number
establishment in cores and slices obtained from trees of known age.
Department of Forestry and Environmental Science,
of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.