Herpetofaunal Diversity and Distribution in Kalugala Proposed Forest Reserve, Western Province of Sri Lanka
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Copyright: © 2012 Botejue and Wattavidanage. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any Amphibian & Reptile Conservation 5(2):65-80. medium, provided the original author and source are credited. Herpetofaunal diversity and distribution in Kalugala proposed forest reserve, Western province of Sri Lanka 1,3W. MADHAVA S. BOTEJUE AND 2JAYANTHA WATTAVIDANAGE 1Taprobanica Nature Conservation Society, 150/6, Stanley Thilakaratne Mawatha, Nugegoda, SRI LANKA 2Department of Zoology, Faculty of Natural Sciences, The Open University of Sri Lanka, SRI LANKA Abstract.—Kalugala Proposed Forest Reserve (KPFR) is a primary lowland tropical rain forest, sur- rounded by secondary forest and vegetation disturbed by human activities such as cultivation, logging, and the collection of firewood. Herpetofaunal communities of selected different habitats (closed forest, forest edge, home gardens, and cultivations) were assessed and distribution pat- terns were compared. A total of 24 amphibian species (63% endemic and 33% Threatened) and 53 reptile species (38% endemic and 30% Threatened) were recorded. Overall, 763 individual amphib- ians and 1032 individual reptiles were recorded in this forest area. Reptilian distribution patterns are similar to amphibian distribution patterns, with the highest diversity in the closed forest and the lowest diversity in cultivations. We did not observe an effect of forest edge (edge effect) in amphib- ian and reptile diversity, except for forest edge and cultivations for reptiles. Adverse human activi- ties such as improper agriculture practices, logging, and waste disposal have led to deforestation and habitat loss in KPFR. Key words. Amphibians, reptiles, conservation, ecology, habitats, rain forest, Sri Lanka, threats Citation: Botejue WMS, Wattavidanage J. 2012. Herpetofaunal diversity and distribution in Kalugala proposed forest reserve, Western province of Sri Lanka. Amphibian & Reptile Conservation 5(2):65-80 (e39). Introduction as deforestation (Bambaradeniya et al. 2003; Brook et al. 2003; Pethiyagoda 2005, 2007a), fire (Batuwita and Ba- hir 2005), erosion (Hewawasam et al. 2003), agrochemi- Recent research has demonstrated the uniqueness of Sri cal use (Pethiyagoda 1994), and lack of systematic or sci- Lankan fauna and its distinctness from the Indian main- entific understanding (Bahir 2009; Pethiyagoda 2007b). land (Bossuyt et al. 2004, 2005; Helgen and Groves Although the natural forest area of Sri Lanka still consti- 2005). This is particularly true of the herpetofaunal tutes over 12% of the total land area (Tan 2005), human assemblage (Bossuyt et al. 2004; Meegaskumbura et population density of the biologically rich wet zone is al. 2002). There are 110 species of amphibians in Sri among the highest on earth (Cincotta et al. 2000). Fur- Lanka, which belong to seven families and 19 genera thermore, the population growth rate is increasing around with 95 (86%) endemic species. (Fernando et al. 2007; protected areas (Wittemyer et al. 2008). Natural forests Frost 2008; Manamendra-Arachchi and Pethiyagoda and the biodiversity have been rapidly diminishing over 2006; Meegaskumbura et al. 2007; Meegaskumbura et the past 100 years. The result has been the extinction of al. 2009; Meegaskumbura et al. 2010; Meegaskumbura 21 species of amphibians, with 19 of these species being and Manamendra-Arachchi 2011). The reptile fauna con- from the genus Pseudophilautus (Manamendra-Arach- sists of 210 species, including 120 (57%) endemic spe- chi and Pethiyagoda 2005; Meegaskumbura and Man- cies, representing 24 families and 82 genera. (Bauer et amendra-Arachchi 2005; Meegaskumbura et al. 2007). al. 2007; Batuwita and Pethiyagoda 2007; de Silva 2006; In addition, of the remaining species, 57 reptiles and 56 Gower and Maduwage 2011; Maduwage et al. 2009; Ma- amphibians are considered Threatened (IUCNSL and namendra-Arachchi et al. 2006; Manamendra-Arachchi MENRSL 2007). et al. 2007; Smith et al. 2008; Somaweera 2006; Wick- Kalugala Proposed Forest Reserve (KPFR) is one of ramasinghe and Munindradasa 2007; Wickramasinghe et the remaining few wet zone forest patches in Sri Lan- al. 2009). ka and is threatened by human activities. We report the In the present period of mass extinction of biodiver- results of a study conducted in KPFR to assess species sity (Achard et al. 2002; Jenkins 2003) many species of richness, abundance, and diversity of the herpetofauna animals, plants, and other organisms are disappearing at and to evaluate the distribution patterns among different an alarming rate, primarily due to human activities such habitats. Correspondence. Email: [email protected] amphibian-reptile-conservation.org 065 January 2012 | Volume 5 | Number 2 | e39 Botejue and Wattavidanage Study area and habitats maintained trails (Fig. 8) and, in some places, the forest is directly connected to cultivations. The KPFR belongs to Agalawatta and Walallawita Divi- The forest edge is the marginal area between closed sional Secretariat of Kaluthara District, Sri Lanka, which forest and home gardens or cultivations. This is highly lies between 6°25’-6°30’ N and 80°12’-80°16’ E (Fig. disturbed by human activities such as logging and fire- 1). The floristic structure and composition suggest KPFR wood collecting. The vegetation of this area consists of retain a considerable amount of primary forest. However a mixture of forest vegetation and home garden vegeta- the boundaries of this forest are disturbed due to cultiva- tion, trees such as Mesua sp., Dipterocarpus sp., Shorea tion, logging, firewood collection, and consist of second- sp., Doona sp., Mangifera zeylanica, Mangifera indica, ary and disturbed vegetation. We identified four types of Caryota urens, Areca catechu, Artocarpus nobilis, Ar- habitats as study sites: closed forest (Fig. 2), forest edge tocarpus heterophyllus, Trema orientalis, Syzygium sp., (Fig. 3), home gardens (Fig. 4), and cultivations (Fig. 5a, Garcinia sp., Murraya paniculata, Elaeocarpus sp., b, c). Macaranga sp., Mallotus sp.; shrubs such as Ochland- Originally, the KPFR was an area of approxiatemly ra stridula, Osbeckia sp., Melastoma malabathricum; 4,630 ha when first declared a Proposed Forest Reserve climbers such as Calamus sp., and tree ferns (Cyathea in 1992. However, due to continuous deforestation, log- sp.). The under growth is very dense in most parts of the ging, agriculture practices, and illegal encroachments, forest edge, where Dicranopteris sp. and many other fern the land area has drastically reduced to about 2,907 ha species dominate. Species of the family Poaceae and As- (Ranasinghe 1995). Several decades ago, KPFR was part teraceae were also found in the ground layer and exotic of the western-most extension of Sinharaja rainforest, however, today it has been diminished to an isolated for- est patch due to extensive deforestation and other human activities (Kekulandala 2002; Ranasinghe 1995). The elevation of the area ranges from 30-300 m and the ma- jority of its precipitation originates from the southwest monsoon (April to September) with a mean annual rain- fall of 4000-5000 mm. The KPFR is a catchment area for both Benthara and Kalu rivers. Average monthly tem- perature in the region is ~27.3 °C (Kekulandala 2002; Ranasinghe 1995). Closed forest is found deep in KPFR and on hill- tops (Fig. 6). The major vegetation formation of this habitat type can be classified as Doona-Dipterocarpus- Mesua series (Ranasinghe 1995). A certain degree of stratification can be identified in the forest, and although an emergent layer cannot be clearly identified, at some places the forest rises up to about 50-60 m in height and is primarily composed of Dipterocarpus sp., Shorea sp., and Doona sp. The canopy layer is composed of Aniso- phyllea cinnamomoides, Mesua sp., Vateria copallifera, and Mangifera zeylanica, that rise to about 30-40 m. The subcanopy is about 15-30 m high with the primary trees being Semecarpus sp., Garcinia sp. Calophyllum sp., and Horsfieldia iryaghedhi. The composition of the under- story is variable, but primarily this layer is comprised of Humboldtia laurifolia, Strobilanthes sp., Cyathea sp., saplings of Calamus sp., and Glochidion sp. The ground layer is mainly composed of species in the fam- ily Poaceae and Asteraceae, as well as ground orchids. This forest harbor a rich assemblage of climbing plants (e.g., Pothos sp., Entada pusaetha, and Calamus sp.) and epiphytes. Exotic species like Alstonia macrophylla are also found in the forest and the ground is covered with a thick and moist decomposing leaf matter layer. A con- siderable number of streams are located in the study area (Fig. 7). Some areas of the forest are disturbed by well- Figure 1. Geographical location and map of KPFR. amphibian-reptile-conservation.org 066 January 2012 | Volume 5 | Number 2 | e39 Herpetofauna of Kalugala proposed forest reserve Figure 2. Closed forest. Figure 3. Forest edge. Figure 4. Home gardens. Figure 5a. Cultivation (paddy). Figure 5b. Cultivation (tea). Figure 5c. Cultivation (rubber). species like Alstonia macrophylla, Dillenia suffruticosa, sp., Nephelium lappaceum, Cinnamomum verum, Plume- Eucalyptus sp., Acacia sp., and Pinus sp. were present in ria sp., Spondias sp., Piper betle, and P. nigrum. Shrubs this habitat type. consist of Melastoma malabathricum, Osbeckia octan- Home garden vegetation consists of crop, shade, and dra, and exotic Lantana