LEAD ARTICLE Biodiversity conservation in Sri Lanka's novel ecosystems

With Sri Lanka‘s old-growth forests having been reduced to less than 20% of their pre-colonial extent, increasing areas of land, formerly heavily influenced by humans, are being allowed to return to secondary forests. These range from land recovering from swidden cultivation in the dry zone, through abandoned tea plantations in the lower-montane zone, to partly-logged forests throughout the country. Although the secondary vegetation of these ‗emerging ecosystems‘ is often dominated by alien plant species and includes only a depauperate native flora, many threatened animals, ranging from amphibians to elephants, are able to utilize them for part or all of their life cycles. These novel ecosystems offer valuable conservation opportunities in two ways: (1) by increasing the area of occupancy of threatened species they contribute directly to a reduction in the level of threat; and (2) they provide a filter for triage, whereby threatened species that are intolerant of modified habitats could be awarded higher priority in the design of recovery plans. Available data suggest that among the Sri Lankan terrestrial vertebrates presently assessed as Endangered or Critically Endangered in the IUCN Red List, 12 of 14 mammal species, three of four reptile species and 40 of 48 amphibian species occur also in emerging ecosystems. Despite their impoverished plant diversity, therefore, such ecosystems should be viewed as a conservation opportunity rather than a threat; they should be incorporated into the national protected areas network and their biodiversity monitored, especially in relation to threatened species.Those that establish stable populations over multiple generations could be down-listed so that greater conservation attention could be allocated to threatened species obligatorily dependent on old-growth forests.