Subproject E02

Dr. Rainer Steinbrecher, Fraunhofer Institute for Atmospheric Environmental Research, Kreuzeckbahnstr.19, 82467 Garmisch-Partenkirchen, Germany

Impact of biodiversity change on the exchange potential of trace gases between ecosystems and atmosphere

Background
Agriculture and forestry contribute to lasting changes in biodiversity. This again effects the exchange of trace gases between forest areas and the atmosphere. Volatile organic compounds (VOCs) emitted from the vegetation in many ways influence the composition of the atmospheric trace gases with local, regional and global impacts on the total radiation budget, the cloud forming capacity, the precipitation, etc. These reactive compounds, however, are important components of the global carbon cycle. They play an outstanding role in atmospheric chemistry, e.g. in the context of ozone and aerosol forming. Further, tropical forests may be potential sources of methane and nitrogen oxides. Both compounds are involved in global warming with varied feedbacks to the biosphere.

Methods
There is yet no detailed knowledge about the impacts of tropical ecosystems with different bio-complexity. Therefore, an interdisciplinary research approach will need to include biologists, meteorologists and geographers. The work performed will focus on:

1.	monitoring the present landscape by means of a satellite imagery-based geographic information system (GIS),
2.	collecting biological data on vegetation and vegetation development (e.g. leaf out and leaf litter fall, blooming and fruiting period of major tree species and leaf area index of investigated forest parts)
3.	measuring climate parameters (e.g. solar radiation and temperature) as well as canopy flux measurements of trace gases (e.g. isoprenoids, CO2, possibly also CH4 and N2O) by use of an ultra-light aircraft.

All data will be refered to geographical co-ordinates. The data will be processed in a way that they will allow a first-ever rain-forest estimate of the trace gas exchange between the biosphere and atmosphere, applying a model especially developed for that purpose (phase 1). This will allow for the first time to describe anthropogenic effects on the biodiversity of tropical forest ecosystems and their impacts on the chemical composition of the tropical atmosphere. In this context also the sources and sinks of CO2, water vapour and other climate relevant compounds will be quantified as these compounds force global climate change with a possibly strong negative feedback to regional climate (e.g. desertification, increased flooding events etc.). It is planned to further develop this model later on and to validate it by field measurements and additional flights with the ultralight aircraft (main phase).
In order to perform flux measurements in Kenya an ultralight aircraft with the necessary equipment will be used. Three campaigns of four weeks each with two people are planned in 2002 and 2003.
The ground survey will be performed by a Kenyan PhD student or a Kenyan scientist.