* Main objective: To characterise changes induced by land use intensification in the flooded neotropical savannahs, mainly through building a network of dams for regulating surface run off: i) Relative weight of some major limiting factors in the productive processes of flooded savannah ecosystems. As limiting factors in primary production, the effects of water regime, fire management, wildlife and cattle herbivory are considered. ii) Within a regional frame, the establishment of the patterns and relative proportions of the main habitat types in the landscape.
* Specific: iii) Elaboration of maps showing the major landscape changes during the last 30 years, resulting from the use of the dam systems for the control of surface run off. iv) Analysis of the diversity of landscapes and communities, and the relationships between the natural environment and the areas under human influence. v) Measurement of water fluxes in a flooded savannah ecosystem, rainfall, soil water, depth of the water table, content and evaporation into non flooded and permanently flooded habitats. vi) Establishment of flooded savannah's floristic composition, diversity and phenological behaviour and their changes in response to various grazing pressures and fire regimes. vii) Estimation of above and belowground primary production under the current management practices by quantifying the above and belowground biomass in a flooded savannah site under three different stocking rates: protected, extensive grazing and overgrazing. viii) Quantification of carbon and nitrogen stocks in vegetation, soil, megafauna and microbial biomass, in the aforementioned treatments. Evaluation of the soil's carbon flux through root and biomass respiration by in situ soil incubation and measuring of CO2 losses. Procurable indicative figures for certain soil-atmosphere nitrogen fluxes: losses through denitrification and gains by biological fixation (free and symbiotic).
Evaluation of the possible changes after considered disturbances. Effect on the biodiversity. Proposal for development according to local and external demand, and for water management systems taking into account the local development (tourism) and the biological diversity maintenance. There is a great demand for ecological information by Governmental offices, environmentalist organisations, tourist services, and the producers themselves (ranchers). The expected results shall have a positive impact on regional development policies, and even on the legislation regulating land use. Scientifically, this project is fully justified as an integrated research combining various complementary approaches to obtain a global understanding of the functioning and dynamics of one of the less known tropical ecosystems, mainly, its diversity, and carbon and water cycles.
1. Landscape scale: a) Habitat heterogeneity and changes induced by land uses during the last 30 years. Consequences of the dams' system. Mapping and description of the study area using satellite imagery. b) Monitoring landscape changes resulting from land use and transformation processes over the last 30 years. Measure of the rate of replacement of the habitat types. Old aerial photocover (1960) will be used. The temporal changes in habitat will be estimated through a GIS. The procedure is: b1) Development of a Digital Terrain Model (DTM). b2) Analysis of the development of forests elements in the savannah. b3) Introduction of the land use data, ecosystem data and the hydrological models into the DTM. c) Water budget of the flooded savannah ecosystem.
2. Ecosystem: d) Productivity and forage quality of flooded savannahs under three different stocking rates. d1) Land resources inventory at plot level. Information on species characteristics, life forms, phenology, soil profile, floristic composition, crop of consumable biomass, production and its relationship with biodiversity, soil respiration, mineral nitrogen and biomass'carbon and nitrogen, soil microbial biomass, denitrification and nitrogen fixation. d2) Animal ecology approach (major plant species consumed through the year, and their caloric values, energy efficiencies, and ratio animal diversity / wetland diversity).
Funding SchemeCSC - Cost-sharing contracts
6703 BJ Wageningen