Patterns in water flux and carbon cycle controls along land use and climate gradients

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Controls on and the magnitudes of component fluxes of water in ecosystems distributed along the elevation gradient from savanna to the alpine zone of Mt. Kilimanjaro will be defined, in order to relate these critical processes to stand level biodiversity. Additionally, carbon gain by the ecosystems will be determined in relation to water use, in order to provide input to simulations of plant growth and production. Characterization of soils in terms of the regulation of water balances and storage will provide information essential to the understanding of soil solution chemistry and nutrient transport. Information gained from the studies at intensive research sites will be summarized in a process-based carbon and water flux model, which generalizes our understanding of controls as we move from the arid zone, to the forest belt, and to the region influenced by cold temperatures at high elevation. A nested experimental strategy is employed that will allow us to include process variation into the model for each ecosystem, based on the possible observations at 48 extensive sites. Within the nested strategy, greatest emphasis is placed on detailed evaluation of processes at the upper and lower forest boundaries where global change influences are greatest (6 cluster sites). We define experimental sites that are clustered around the lower forest boundary, where anthropogenic activities increasingly modify the natural vegetation, and around the upper forest boundary, where climate change has led to increased fire frequency. Cluster sites belong also to a collection of 12 focal sites, one in each ecosystem type under investigation, where either very detailed process studies (cluster sites) or intensive campaigns are carried out. The long-term product of the research will be a stand level model for carbon and water fluxes and annual balances that may be applied in landscape level simulations for the Mt. Kilimanjaro region.