STRUCTURE AND FLORISTIC COMPOSITION OF GANNORUWA FOREST.

Udayani R Weerasinghe*
P Jayasekara* and W Dissanayake**
* National Herbarium; ** Forest Department

Gannoruwa forest is a remnant forest patch of about 267 hectares situated in Kandy district close to the Royal Botanical Garden, Peradeniya.

Plots (of 50 m by 5 m) were laid out at regular intervals along environmental gradients in order to sample the full range of floral diversity from lowest levels to ridge tops. All the woody plants above 10 cm girth at breast height (G.B.H.) within plots were enumerated and other smaller woody species (shrubs, herbs, seedling and saplings) were noted. Floristic structure; density, basal area and height and floristic composition; floristic richness and density dominance of woody flora were evaluated to gather scientific guidelines and baseline information of the study site.

The vegetation of the area is dominated by lowland evergreen mixed vegetation. So far more than 110 species have been recorded in different girth classes. At the upper elevation, girth sizes and basal area were higher than at the lower elevation. As a result of human habitation of the lower area, the natural forest has been degraded to a larger extent. Some areas of the Gannoruwa forest were relatively little disturbed and contain old massive trees. A high percent of basal area is mainly contributed by native taxa in these areas. Some of these are Artocarpus nobilis, Mangifera zeylanica, Nothopegia beddomei, Neolitsea cassia, Pometia tomentosa, Diospyros racemosa, Hydnocarpus venenata and Myristica dactyloides. Some exotics; Michelia champaca, Alstonia macrophylla and Swietenia macrophylla were also found in this area.

It is evident that Gannoruwa forest provides a natural refugium as in-situ conservation for many native endemic species. Also it acts as a natural buffer in disease outbreaks and as a habitat for pollinating and dispersing agents for the surrounding area and Royal Botanic Gardens. If Gannoruwa can be protected as a natural reserve it would be a valuable educational site. Students can compare both ex-situ conservation area (Royal Botanical Gardens) with natural in-situ conservation Gannoruwa forest. This study is continuing.

Department of Forestry and Environmental Science,
University of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.