Distribution,habitat associations and conservation implications of Sri Lankan freshwater terrapins outside the protected area network

1. Terrapins are integral to many freshwater ecosystems, yet are imperilled at a global scale. In Sri Lanka, terrapins are understudied; thus, much of their natural history and distribution status remain unknown. Such paucity of studies impedes conservation.
2. In this study, 79 freshwater habitats located outside the protected area network of south‐western Sri Lanka were surveyed to document current population densities and habitat use of two terrapin species: Indian black terrapin (Melanochelys trijuga thermalis ) and flap‐shelled terrapin (Lissemys ceylonensis ). Local inhabitants were interviewed to assess human threats towards terrapins.
3. Both species were recorded in low densities: 1–2 individuals ha^?1. Indian black terrapin was found in half of the surveyed sites while flap‐shelled terrapin occurred in one‐third of the surveyed sites. Highly urbanized river basins had the lowest densities for both species while rural basins supported higher numbers. Basking was the predominant behaviour of both species and large woody debris and boulders were preferred as basking substrates, together with sparse‐canopy aquatic habitats with intact marshlands.
4. Overharvesting for meat was a major threat for terrapins. Most local inhabitants were unaware of legislation on terrapin conservation and the ecological importance of terrapins. Human threats such as pollution, modification of aquatic and wetland habitats, and loss of riparian forests were frequently observed in surveyed sites. Terrapin populations outside the protected area are at risk as evidenced by lower population densities and a multitude of human threats.
5. A landscape‐scale ecosystem‐based conservation approach is recommended for Sri Lanka's terrapins with incorporation of lands with different management regimes (privately owned, municipality managed) into the protected area network. Current environmental legislation should be revised to support buffer zone delineation for aquatic habitats, wetland restoration, and landscape‐scale connectivity.

     

Release from root competition promotes tree seedling survival and growth following transplantation into human-induced grasslands in Sri Lanka

The density of colonising tree seedlings is often very low in degraded human-induced tropical grasslands. To investigate the mechanisms that constrain seedling establishment in grasslands on former tea plantations in Sri Lanka we planted seedlings of the native tree species Dimocarpus longan Lour., Macaranga indica Wight, Symplocos cochinchinensis (Lour.) S. Moore and Syzygium spathulatum Thw. and examined effects of vertebrate herbivory, and above- and below-ground competition exerted by the grass sward on seedling growth and survival over 28 months. Seedlings of the same species were also planted in remnant patches of lower montane rain forest to determine the effects of habitat on seedling growth and survival. Less than 40% of seedlings survived to 28 months post-transplantation. The highest survival was recorded for Symplocos cochinchinensis in both grassland and forest, while Macaranga indica seedlings had the highest relative growth rate of height (RGRh) in both habitats. Root competition reduced survival of Macaranga indica and the RGR_h of Macaranga indica, Symplocos cochinchinensis and Syzygium spathulatum in the grassland, while above-ground competition and exclusion of vertebrate herbivores had no effects on seedling establishment. These results suggest that Symplocos cochinchinensis would be suitable for re-establishing forest cover on degraded grasslands, although Macaranga indica would be more likely to catalyse succession because it possesses animal-dispersed fruit. Measures that overcome or restrict the effects of root competition from grasses would enhance tree seedling growth and survival more than manipulation of the light environment or protection from vertebrate herbivores.