B1 - Energy and mass exchange between atmosphere and tropical ecosystems

Abstract
In B1 H2O-, CO2- and energy fluxes between the atmosphere and a natural rain forest and other land use types relevant in the rain forest margin zone will be quantified by field measurements and by numerical modelling, so that water availability, and CO2- fluxes, plant production and local climate influences can be assessed. A meteorological network will be run to regionalize atmospheric properties for studied areas to support ecological and socio-economic research. Events of ENSO will be characterized on regional and local scale and its short/long term effects on the forest margin zone will be predicted and quantitatively described.

Summary
The main aim of Subproject B1 is to describe quantitatively the processes of energy, H2Oand CO2-exchange between the atmosphere and rainforest/agroforestry ecosystems which influence the natural and anthropogenic dynamic of the rainforest margin zone. The occurrence of stress conditions like droughts caused by warm events of ENSO affects the current state of tropical ecosystems and its future changes. Therefore, it is necessary to describe atmosphere-ecosystem-interaction and its effects on the different vegetation types under “normal” and under ENSO-stressed conditions. Stabilization/destabilization processes of rainforest margins caused by climatic influences can thus be better evaluated. To reach the main goal, the following questions should be answered and tasks completed:

a) H2O-, CO2- and energy fluxes between the atmosphere and a natural rain forest and agroforestry ecosystems relevant to the rain forest margin zone will be quantified by field measurements and by numerical modelling, so that water availability, and CO2- fluxes, plant production and local climate influences can be assessed. The contribution of vertical and horizontal advection to CO2- and heat fluxes across ecosystem boundaries could be significant and will be, therefore, estimated.

b) Contributions of separate internal ecosystem fluxes (wood- and soil respiration, photosynthesis, soil- and interception evaporation, transpiration) to the CO2- and H2O-fluxes across the ecosystem boundaries will be quantified to improve the understating of transport processes and to correct the interpretation of fluxes measurements.

c) The effects of ENSO events (El Niño, La Nina) on the forest margin zone of the Lore Lindu National Park will be studied at local and regional levels by means of micrometeorological measurements and modelling. Besides that, the effects of warm event will be investigated within the research of Focus 3 at a “roof site”. In a case of a warm event occurrence the micrometeorology of a “roof” could be examined on a correspondence to reality.

d) A meteorological network will be run to regionalize atmospheric properties for studied areas to support ecological and socioeconomic research with the information required to characterize a background climatic influence.

In this way the sub-project B1 contributes to all three Foci of joint Project and thus, to achievement of main project’s goal – the investigation of rainforest margins stability.