Plant diversity and its ecophysiological characters determine the function of an ecosystem service: Geger spring water conservation case in Bantul Yogyakarta

Retno Peni Sancayaningsih^*)

Laboratory of Ecology and Conservation, Biological Department, Gadjah Mada University, Yogyakarta, Indonesia

e-mail : retpeni@ugm.ac.id

Abstract

Water Catchment Area (WCA) is an ecosystem that is very important to conserve a spring. Beside geohydrological condition, plant cover of WCA and soils are determinant factors that may influence spring water debit. WCA of Geger spring with area of 9,87 ha width, 68 % of its landuses had been changed lately. Due to its gradual decrease of water debit, therefore, ecophysiological study of vegetation in WCA and its surrounding were conducted. WCA was constructed using quickbird sattelite imagery using Arc-GIS computer software. Vegetation classes were predicted using NDVI approach and ground cheque of vegetation analysis using 10 x 10 m² of 40 plots. Physiological characters of 5 selected trees (Ficus benjamina, Tectona grandis, Zizygium aquaticum, Gnetum gnemon, dan Inocarpus fagiferus) were recorded from its model seedlings using Li-Cor 6400, and its water absorbtion by plant roots were also recorded. Of these 5 model species, I. fagiferus, G. gnemon, and Z. aquaticum are less transpire water than two other species, and T. grandis seedling is the highest in absorbing water from soils, is almost the same as 2 years old F. benjamina sapling. Fast growing species is predicted to take more water, and slow growing species uses water more efficiently. Composition of plant cover and its width in a WCA will influence spring water conservation.

Key words: WCA, spring water conservation, slow growing species