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Sri Lankan Moist Forests Ecoregion: An Imperiled Island Rainforest

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Abstract

The Sri Lankan Moist Forests ecoregion represents the moist forests of southwest and central Sri Lanka that harbors exceptional endemism, including unique higher taxa. Imperilment of the ecoregion began two centuries ago, when the British colonial government began large-scale forest clearing for commodity crops; first coffee and then tea. Forest clearing and degradation continues, although at a decelerated pace because of forest protection regulations initiated in the early 1900s. A system of 269 protected areas now offer some refuge for biodiversity that has evolved, adapted, and survived through 200 million years of continental rifting and drifting, tectonic activity, and climatic changes over several geological epochs. Endemism is particularly high among non-vagile, smaller faunal and floral groups, among which are relict biota with links to Gondwanaland. The floristic uniqueness of the ecoregion is reflected by a community that includes 15 endemic genera with 55 species from 12 Families. The forest canopy is dominated by two endemic genera, Doona and Stemonoporus, in the Family Dipterocarpaceae, which characterizes most Asian moist forests. High floristic richness and alpha- and beta-diversity is reflected by 10 floristic zones. Faunal diversity and endemism are comparably rich. There are 13 endemic mammal species including two endemic, monotypic genera, Solisorex and Srilankamys, and 25 endemic bird species. Endemism is even more pronounced in the lower taxonomic groups, now restricted to forest fragments. Conservation of this ecoregion should therefore be the highest priority for Sri Lanka given the contribution of irreplaceable species to the global biodiversity repository. Conservation strategies include establishing connectivity among forest patches and expanding forested areas through restoration. Such strategies have multiple benefits, including clean water, non-timber forest products, flood and landslide protection, support for lives and livelihoods, sustainable economies, and stable governance. The inclusion of private-sector forest management in the Forestry Sector Master Plan offers an opportunity for forest restoration through public-private partnerships using traditional forest management practices.

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Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
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