IR. ELIYANI1, IR. HANDOKO2, RONALD F. KÜHNE3
1Bogor Agricultural University (IPB), Agroclimatology, Indonesia
2SEAMEO-BIOTROP, Bogor, Indonesia
3Georg-August-Universität Göttingen, Institute for Plant and Animal Production in the Tropics, Germany
Forest degradation in Indonesia is mainly caused by land use change and logging. This is accelerated by slash-and-burn practices of poor farmers, economic turmoil and high demand for wood. One approach to reduce forest degradation is to cultivate trees which have economic and ecological value such as fast growing teak (Tectona grandis LINN. FILL.). However, information on growth response of this kind of teak to environment is very limited. The objective of the research is to calibrate a simulation model that can describe the relationship between fast growing teak growth and soil water availability, one of the important factors which has a high variability in Indonesia. The model can be used for zoning, risk analysis, and land management.
The research consists of a modelling project and a field experiment to obtain model parameters. The field experiment was conducted for two years in Java, Indonesia with three levels of irrigation: control (0), 7 and mmday to reflect varying seasonal water regime. The measurements included phenology, growth, climate variables and soil water content. The model consists of three sub-models, i.e. phenology, growth, and soil water balance.
The results show that soil water availability is a very important limiting factor for the early growth of fast growing teak. Strong water stress led to missing plants due to wilting. Irrigation produced higher tree volume and biomass than control. However, mmday was not significantly different from mmday. Rates of leaf emergence and leaf drop are affected by water availability. Water stress delayed leaf emergence and accelerated leaf drop. Carbon content in plants was not affected by water availability.
Preliminary results from simulation runs show that the calibrated model describes the dynamics of early growth and carbon sequestration but needs further validation.
Keywords: Carbon sequestration, decision support, fast growing teak, Indonesia, simulation model