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The wide range of ecosystem diversity in Sri Lanka has resulted in high species diversity.
Among them rock out crops are special habitats and are hardly studied. Rocks are being
extracted for construction purposes in developmental activities. This may cause loss of
endemic, rare, threatened or highly localized species, which may be found in the rock out
crops. In this study, the emphasis was given to floral diversity associated with undisturbed or
least disturbed rock out crops in wet lowlands.
Sites were identified according to visual observations as well as randomly from the map of
the Forest Department on Conservation Forests, wet zone. The Plots were identified by a
visual reconnaissance survey and several circular plots of different sizes were laid out
according to the site. The flora observed and the number of individuals were recorded. The
study was concentrated on trees and shrubs but vines, epiphytes, ferns and some herbaceous
plants were also recorded excluding grasses. General collection of flora out side the plots
were taken. Altogether 15 sites have been surveyed.
It was observed that most of the sites consist of similar types of vegetation. Variations among
the sites regarding floral diversity were therefore limited. But there were species in rock
outcrops that differed from the surrounding vegetation.
Further, rock outcrops contained a considerable amount of endemic species, threatened
species and rare species. Altitude and the number of species present showed no significant
linear relationship. Regarding the degree of disturbance among sites and the diversity, there
was no significant relationship shown. The sites showed xeric conditions and some of the
species were generally found in dry habitats. Sometimes, plants showed an exposed root
system and stunted growth.
There is a considerable amount of diversity associated with rock outcrops and as habitats
become rare, species associated with them could also become rare, therefore conservation
measures should be taken where possible.
