A floristic survey of a unique lowland rain forest in Moraella in the Knuckles valley, Sir Lanka

Abstract

The luxuriant natural forests of the western lower slopes and valleys of the Knuckles range have been heavily deforested since the mid-19th century for conversion to coffee and tea plantations. Consequently, only scant floristic and ecological signatures of the original vegetation are still found, notably as scattered enclaves along stream reservations. Recently, an isolated forest fragment at 500-700 m amsl, not recorded previously, was located in Moraella in the valley of Kukul Oya (stream) in the south western foothills of Knuckles range. A vegetation survey of this forest recorded a total of 204 flowering plant species in 70 families. Eighty-nine (44%) of the species are endemic to Sri Lanka, while 39 (20%) are nationally threatened. Among the 148 tree, treelet and shrub species identified, 74 (50%) have not been recorded during previous floral surveys of the Knuckles forest reserve, while115 (78%) are common to the lowland rain forests of south-western Sri Lanka. The existence of a similar forest fragment located near Kosgama on the banks of Hulu Ganga (river), suggests that they represent remnants of a once extensive lowland rain forest formation. These forest fragments likely mark the north-eastern-most limits of distribution of lowland rain forests in Sri Lanka and warrant urgent conservation as biodiversity refugia. They may be the last vestiges of an almost disappearing lowland rain forest type in the Knuckles range.   Key words: Sri Lankan flora, Dipterocarpaceae, ‘Dumbara Mitiyawatha’, refugia DOI: http://dx.doi.org/10.4038/cjsbs.v40i1.3405 CJSBS 2011; 40(1): 33-51