Role of human agency in the transformation of the biogeography of Sri Lanka

The area referred to as the ‘Central Highlands of Sri Lanka’, despite being the venue of a thin scatter of ‘Stone Age’ human settlements was sparsely populated by man throughout the island’s ‘Pre-Modern Era’, and much of it, especially at its higher elevations remaining under primeval forest cover. In late medieval times when this highland area became a part of the ‘Kandyan Kingdom’, its forest-clad localities, except those that were appurtenant to village settlement ecology, tended to be strictly protected under royal decree. The cultivation of coffee on large areas of land – ‘plantations’ or ‘estates’ –commenced as a major economic enterprise after the establishment of British rule over the island in the early 19th century. This invariably entailed the extensive clearing of forests. The ‘Ferguson map’ that depicts the coffee estates that existed in 1863 and 1880 provides valuable information about the distribution of coffee plantations. The present study is a product of an attempt to determine the location and the extent of coffee plantations in relation to vegetation zones, administrative districts, and river basins of the Central Highlands. It indicates, inter alia, the main plantation area in the Upper Mahaveli catchment, and in the sub-montane zone. The second largest extent was in the Kelani Basin. Clearing of forests led to erosion of hillslopes, siltation of riverbeds and the low-lying areas, particularly in these two river basins. Within a period of 50 years the landscape of a large part of the Central Highlands was transformed from forest-covered hills to a landscape dominated by plantations. This process caused irreparable damage to the biodiversity of the montane and sub-montane areas of Sri Lanka.Keywords: endemism, evolutionary stable unit, mammal subspecies, habitat quality, ecological niche, mammalian evolution