Connecting forests in a biodiversity hotspot: the Hiniduma Biolink
Sri Lanka is an island with a land area of 6,570,134 ha and a coastline of 1,600 km. The island consists of a broad coastal plain and a central mountainous area with elevations rising to 2,500 m. These differences in rainfall and altitude result in a wide variety of terrestrial ecosystems.
The forests of southwestern Sri Lanka are considered one of a handful of “biodiversity hotspots” in the world. When declaring an area to be a ‘biodiversity hotspot’, scientists consider the number of organisms unique to a particular region, total number of species, and the high risk of human activities. The forests of southwestern Sri Lanka are comprised of the remaining natural ecosystem along the Gin River from its origins in the southern forests of the Singharaja, a forest cluster in the Hiniduma region, and the Kanneliya cluster, which extends to the Hikkaduwa marine sanctuary situated at the confluence of the Gin river with the Indian Ocean. This landscape-seascape conservation area is a key conservation priority in this biodiversity hotspot. The rainforests of the wet zone contain nearly all of the country’s woody endemic plants and about 75 per cent of the endemic animals.
Tropical rainforests in Sri Lanka have been reduced to the point that they cover less than 6% of the land surface in isolated patches. These patches contain a vast number of endemic plants and animals, which have now become isolated from other populations. Thus, our biological heritage is in imminent danger of widespread extinction unless drastic action is taken. For example, all endemic birds in Sri Lanka live in the rainforests, and some of them are considered to be globally threatened.
Various research and conservation programs have been conducted in isolated rainforest patches in the Galle district on amphibians, reptiles, snails, dragonflies etc. Furthermore, due to the spike of taxonomic research, especially in the lowland wet zone forests, many new species are being discovered. Hence, these findings call for the conservation and protection of these valuable lowland forest habitats.
Developing a bio-link between isolated forest patches is vital for conserving the future of Sri Lankan biodiversity. Isolated gene pools in fragmented landscapes lead to homogenous populations which are less likely to survive in the long term. Although much of the original extent of the rainforest has been reduced, 18,910 acres of this rain forest still exists in Galle District, covering about 11% district’s area. Tropical lowland rainforests are commonly found at elevations less than 1000 m above mean sea level. These forests receive an annual rainfall of 2500-5000 mm, free of long dry spells, and are evergreen with no significant seasonal changes. A clear stratification can be observed in these forests to obtain sunlight.
Many plant communities are found here such as the Dipterocarpus community (Dipterocarpus zeylanicus and Dipterocarpus hispidus), the Mesua-Doona community, and the Vitex-Dillenia- Anisophyllea community. Conservation of these tropical forests is crucial as much of Sri Lanka’s endemic flora and fauna are found in this valuable ecosystem.
Rainforest Rescue International in Sri Lanka has a project called “Hiniduma Biolink Project, Sri Lanka – Reforesting traditional home gardens using the analog forestry concept in wet zones of Sri Lanka”, which focuses on the establishment of a biodiversity corridor between the two large remnant disturbed rainforest patches in Sri Lanka (Kanneliya Man and Biosphere reserve and Sinharaja World Heritage site) and to conserve buffer zones at the forest edges.
All photos by Anuradha Ediriweera