Valuation of Key Freshwater Ecosystem Services: A Case Study in Yagirala Rainforest

Abstract

Tropical lowland rainforests in Sri Lanka are subjected to degradation due mainly to conversion to
other uses and population pressure. Valuation of ecosystem services has become important in terms
of conservation of such landscapes. This study intends to estimate economic value of key freshwater
aquatic ecosystem services associated with tributary ecosystem in the Yagirala Forest Reserve, a
fragmented tropical lowland rainforest in south-west Sri Lanka. Surface water discharged from the
tributary and the ornamental fish were identified as main provisioning services and recreation and
education were identified as cultural services of the tributary. Physical measurements on freshwater
resource and fish fauna were carried out at eleven sampling points along the selected tributary during
the rainy season. Water flow was measured at the end point of the tributary, which connects to the
main stream using flow rate measuring method. Economic value of water used for
agriculture/industrial and potable/domestic use were estimated based on the tariff rates available.
Ornamental fish fauna was counted using transects and valued using market prices related to export
trade. Cultural services were valued based on visitor data maintained at the Research Centre at
Yagirala. Economic value of water available for agricultural activities and industrial purposes were
estimated as LKR 39 million and 3 million respectively. Value of water used for domestic purposes
was LKR 9 million. Economic value of potential ornamental fish of the tributary was estimated as
LKR 41 thousand for three species and considering sustainable extraction. Cultural services were
estimated as LKR 14 thousand. The total value of the selected ecosystem services of the tributary for
3 months was estimated as LKR 51 million. The study highlights the importance of combining
physical data in the economic valuation. The estimated values could provide justification for the
protection of these ecosystems and investments for further value additions.

Keywords: Ecosystem services, Yagirala forest reserve, Economic value, Fresh water