INVASIVE BEHAVIOUR OF Myroxylon balsamum AT UDAWATTAKELE
H.P. Wedathanthri and H.M.G.S.B. Hitinayake
Department of Crop Science, Faculty of Agriculture,
University of Peradeniya.
Udawattakele forest is a national heritage of Sri Lanka which has rich
flora and fauna. There are about 460 plant species including 135 tree
species and 11 liana species, of which 9 species are endemic to Sri Lanka.
When considering floristic composition of Udawattakele it is dominated
by Swietenia macrophylla (mahogany), Michelia champaca (gini-sapu), Mesua
ferrea (na) and Myroxylon balsamum (katta kumanchal). Senadhera (1997)
has reported that Myroxylon balsamum has become invasive in some parts
of the forest. The objectives of this investigation was to estimate the
invasive behaviour of Myroxylon balsamum at Udawattakele forest reserve.
Plots of 10 m x 15 m were used for sampling of overstory vegetation and
10 m x 10 m plots were used for understory. Plots were located randomly
in Myroxylon balsamum dominant regions in the forest and measurements
taken were number of individuals and their species, tree height (m), stem
diameter (m) at breast height (1.3 m above ground level) and crown diameter
(m) in order to evaluate species diversity and dominance. Germination
of Myroxylon balsamum seeds were evaluated under four different light
levels (full sunlight, 70% and 35% light and complete dark conditions).
A map was prepared to show the distribution and density of Myroxylon at
various parts of Udawattakele forest reserve.
Results showed that Myroxylon has dominated the understory even when a
few mother plants were available in the overstory. This could be attributed
to prolific seed production capacity, its ability to germinate under wide
range of light conditions, favourable micro-climatic conditions presenting
in the understory and absence of any seed pest or pathogen. Further results
clearly showed that Myroxylon invasion had resulted in the decline of
species diversity of the forest.
If no control measures are applied, there is a possibility that this species
could invade the other parts of the forest in the long term. Therefore
necessary action must be taken immediately to control Myroxylon balsamum.
This could be done by uprooting seedlings, collecting and destroying seeds
and thinning some mother trees. Further understanding of the efficiency
of key physiological processes of Myroxylon including water use efficiency
and stomatal conductance could be useful in deciding measures to control
Further examinations of the dynamics of the Myroxylon seedling bank and
competition taking place at some parts of the forest between mahogany,
Myroxylon and na for the dominance could be useful in the management and
maintenance of the species diversity of Udawattakele forest reserve.
Department of Forestry and Environmental Science,
of Sri Jayewardenepura,Sri Lanka. 1995-2000. All rights reserved.