PhD Project

PhD project

Changes in the hydrological cycle along a gradient of forest use intensity. Project B4, SFB 552 (Stability of Tropical Rain Forest Margins, Indonesia)
DFG. Since 2003.

Management activities in tropical forests are expected to change the forest hydrological cycle with respect to all major fluxes including rainfall interception, stemflow, throughfall, transpiration, and soil water transfer. Thus, an important ecosystem service of the forest is affected as it serves as drinking water reservoir, provides water for rice cultivation and prevents settlements from floods. The forest margin zone of Lore Lindu National Park (LLNP) in Sulawesi is characterised by a gradient of increasing forest use intensity from natural forest in the interior to selectively used forest (rattan and local timber extraction) and agroforestry systems with remaining rainforest shade trees at the margin.
Determinants of rainfall interception and rainfall partitioning in tropical forests are stand structural characteristics such as tree species composition, leaf area index, stem density and the size and number of gaps. Our previous studies in the project region on stand structural characteristics in different forested land-use systems have indicated significant differences in leaf size distribution, leaf area and leaf inclination among various ecosystem types of the forest margin zone. Rainfall interception studies from other tropical regions have demonstrated a large variation in interception among different land-use systems that is related to vegetation structure and type of management. However, the observed differences in interception have not been linked successfully to specific stand structural parameters. This is a prerequisite of a mechanistic model of rainfall interception in tropical forests which could predict interception in differently disturbed forests. Such an approach requires detailed studies on stand structure, experiments on canopy water storage capacities, and the development of an appropriate model.
Objectives of this project are (1) to analyse differences in forest canopy structure and associated rainfall interception along a gradient of forest use intensity, (2) to experimentally determine canopy water storage capacity of different plant surfaces, (3) to identify key factors, which control rainfall interception, by a modelling approach, and (4) to determine differences among forest types in spatial distribution of net precipitation and soil water infiltration capacity (saturated hydraulic conductivity). The results shall represent a basis for an ecologically sound forest management with respect to water resources.

Prof. Dr. D. Hölscher (Institute of Silviculture/Dept. of Tropical Silviculture, University of Göttingen)
Prof. Dr. Ch. Leuschner (Institute of Ecology and Ecosystem Research, University of Göttingen)