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

Wwmab Medawatte,Iaun Gunatilleke,Ku Tennakoon,Cvs Gunatilleke,Emb Ekanayake

doi:10.4038/cjsbs.v40i1.3405

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

Highlights

The Knuckles range ( ), in the Kandy and Matale districts is a northern outlier of the central highlands in Sri Lanka; its peaks are frequently it is locally as ‘Dumbara Kanduwetiya’
Due to its geographic location, graphic varia and altitudinal range, the K exhibits a variety of climatic regimes ranging from wet on the SW and western slopes
The objectives of this investigation were twofold: (i) to carry out a floristic inventory of the remnant forest patches on the lower western foothills of the KR and list the species therein; (ii) to determine to what extent the flora of this forest resemble that of the lowland wet evergreen forests or rain forests of SW Sri Lanka and the lowland semi-evergreen and lower montane forests described previously from the KR

Summary

Introduction

The Knuckles range ( ), in the Kandy and Matale districts is a northern outlier of the central highlands in Sri Lanka; its peaks are frequently it is locally as ‘Dumbara Kanduwetiya’. ‘ ’The south-western (SW) and southern sides of the is separated from the main central highlands by the valley of the Mahaweli river (de Rosayro, 1958), bordering its eastern lowlands.the left bank of the river is commonly known as the ‘Dumbara Mitiyawatha’(meaning ‘mist valley’; Cooray, 1984).The name Knuckles, was given to it by British surveyors, as its main massif (Fig. 1)resembles a clenched fist (Bambaradeniya and Ekanayake, 2003). The south-western (SW) and southern sides of the is separated from the main central highlands by the valley of the Mahaweli river (de Rosayro, 1958), bordering its eastern lowlands. The name Knuckles, was given to it by British surveyors, as its main massif (Fig. 1). The main KR, lying approximately 50 km from Bowatanna reservoir of the Amban Ganga (north-western end; Ganga = river) to Randenigala reservoir of Mahaweli Ganga (south-eastern end), has four major lateral ranges descending towards the north-eastern (NE) (Rambukoluwa range), eastern (Kalupahana range and Dumbanagala range) and SW (Hunnasgiriya range) lowlands (Fig. 2). Due to its geographic location, graphic varia and altitudinal range, the K exhibits a variety of climatic regimes ranging from wet on the SW and western slopes. The whole region receives rain mainly from the NE monsoons that prevail from

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