Characterizing forest ecosystem services degradation within water catchments. An application to a South West Pacific tropical and semi-arid island (New Caledonia)

Abstract New Caledonia is a tropical semi-arid archipelago in the Southwest Pacific. It is a hotspot of threatened biodiversity. Almost entirely covered in forest before human settlement, the mountainous main island, Grande-Terre, has been subject to fire and mine related deforestation since the 19th century. The degradation of the forest has led to loss of the following ecosystem services: soil stabilization, resilience to anthropogenic pressure, and water buffering. In this study, we quantified the loss of these services through remote sensing, modeling and a statistical approach within water catchment perimeters. The main result is a synthetic geographical database of the water catchment perimeters indicating for each the loss of functions as regards the forest's ecosystem services. In the main island, we found that 54% of the water catchment perimeters were highly degraded, 38% were degraded and only 8% slightly degraded. On this basis, our findings have been presented to public bodies and decision makers in order to raise awareness and to encourage the implementation of appropriate forest management measures.