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Since the 1980s, the state of Mato Grosso, Brazil, exhibits high rates of Cerrado conversion in favour of soybean expansion and cattle ranching. This conversion process becomes obvious in the upper Rio das Mortes macro-catchment. The objective of this study was to assess the influence of future land use changes on the discharge dynamics of the Rio das Mortes River. A single catchment approach was applied with the physically-based water balance simulation model WaSiM 8.5.0 (Schulla and jaSper 2007) to simulate land use scenarios. In Scenario 1, only small pasture sites (< 1 km²) were converted into the respective land use type surrounding them (i.e. cropland or Cerrado vegetation), whereas in Scenario 2 all pasture sites were converted into cropland and all Cerrado patches were then transformed into pastures. The WaSiM model was calibrated and validated based on discharge data measured at two gauging stations, achieving Nash-Sutcliffe coeffcients of 0.81 calibration) and 0.68 (validation). Main problems in modelling arise because of scarce spatial distributed data on subsurface parameter and vegetation parameter (Cerrado biome). Therefore, the use of the numerical groundwater model and manifold calibration runs were essential in this modelling approach to allow the simulation of the high levels of baseflow during the dry season and the transition from the dry to the wet season. The immediate rise of the baseflow in response to the increasing precipitation at beginning of the rainy season is a result of high soil hydraulic conductivity and groundwater recharge. These soil characteristics apparently persist on newly-created pasture and cropland sites, which still exhibit high ksat values after deforestation. Simulated evapotranspiration is comparable to literature values (Eddy flux measurements, MODIS-EVI calculation) and recently done paired micro-catchment studies in this catchment. The scenario analysis indicates that there are only small differences in runoff \ud volume, which is directly related to the precipitation changes. In the scenario 2, groundwater recharge and base flow increase, whereas surface runoff does not. Therefore, the ongoing land use intensification with pasture conversion to cropland, remaining high infiltration and slight increase of evapotranspiration may not change runoff volume and discharge characteristics.

In the densely settled Bragantina region, northern Brazil, smallholder cattle pastures start into compulsory degradation processes indicated, among other factors by the woody encroachment of the resprouting secondary vegetation, nationally called "capoeira". By means of Landsat and QuickBird satellite imagery techniques different stages of treedominated pastures were identified and the distribution of degraded pastures quantified. This was tested in a supervised Landsat classification from 2006 and 2007, taking QuickBird imageries from 2004 and 2005 as additional ground checks. We found that 42% of the rural Bragantinian landscape has already converted into pastures, 28% in advanced stages of above ground pasture degradation. Our reclassification means that the region is still confronted with a serious ecological pasture problem and that conventional land use classifications, climatological models and carbon calculations, based on Landsat imageries only, underestimate pasture distribution and thus lead to inaccurate extrapolations. As the resprouting shrubs of the capoeira are a permanent problem on tropical lowland pastures but, on the other hand, are also the ecological basis of the sustainable slash-and-burn systems of smallholders, we tested some innovative strategies to tolerate various useful woody components of the capoeira on pastures to stabilise them ecologically: first, a buffet trial shows that the ten tested capoeira and some other common domesticated tree species obtain a comparable palatability as well-known woody forage legumes. Thus, Cecropia palmata and Tithonia diversifolia, among others, were as palatable for cattle as the well-known multi-purpose legume Cratylia argentea. As a consequence, these freely accessible tree species should not be slashed but fostered on pastures, like supplementary forage plants. Secondly, it is demonstrated that the multi-purpose forage legumes C. argentea and Flemingia macrophylla perform better under smallholder management than under large scaled farming or even intense management due to the associated prolonged restoration times. In sum, we could demonstrate that woody components (capoeira and/ or woody legumes) are more appropriate for the humid tropics than pure grass-monocultures. Based on these experiences, we modified the model of a grass-capoeira-legume pasture, incorporating pastures just as an interim stage of the slash-andburn system. Forage production could be enhanced in that system by selective slashing of the capoeira (palatable species are tolerated) and by incorporating woody forage legumes. As this biome is known to restore its ecosystem fertility rather in its above-ground biomass than in its poor soils, woody components on pastures are recommended for ecologically sustainable production systems. Furthermore, they might be requisite to mitigate the proclaimed climatic change in the Amazon.

Economic problems generate large secondary tropical forests due to crop abandonment; lianas (woody vines climbing upon trees) proliferate there. Lianas generally retard the growth and carbon capture of trees, potentially enhancing global change. It is not known whether all liana species play such a role and which land-use disturbances determined the cur rent species composition of liana communities. We surveyed all lianas >lcm diameter at ground level and all trees > 3.16 cm diameter at 1.3 m above ground in twelve plots 20 x 20-m each in semi-evergreen tropical forests in Northeastern Yucatan Peninsula, Mexico, re-measuring the trees 15 mo later. Lianas were classified into two anatomic types: "hard" (typical stem with compact xylem masses) and "soft" (with much parenchyma and wide xylem vessels). History, archaeology, anthropol ogy, and remote sensing studies, as well as non-formal interviews were used to determine the land-use history of each stand. Increasing densities of the hard liana Dalbergia glabra (Leguminosae), but not of soft lianas ?Arrabidaea spp, Cydista sp, Melloa spp (Bignoniaceae) and Serjania sp (Sapindaceae), were related to more rapid relative growth rates of trees (Linear regression, R2 = 0.680, P = 0.001). Where D. glabra dominated, the trees hosting it grew more rapidly, but trees with large liana-tangles grew more slowly where soft lianas were dominant (Kruskall Wallis, P > 0.01 in both cases). The anatomy of soft lianas sug gests that they are less able to survive burn after slash during shifting cultivation than D. glabra the previous land use where D. glabra dominated. Soft-liana dominated stands were not burnt but subjected to liana-cut during logging and extraction of lianas, palm leaves and latex from Manilkara %apota trees. Our results suggest that some lianas enhance carbon capture mitigating global change, whereas others do not and that the dominance of one liana species is a legacy of previous land use, which is better understood by combining natural and social sciences.

Summary: The present land cover of humid tropical catchment areas mainly regulates the flow of vapour to the atmosphere.Therefore land use decisions play an important role for the water balance of a tropical catchment. Studies that relate land coverchanges with river discharge changes for humid tropical catchment areas at the mesoscale level are rare. This article applies anintegrated remote sensing and hydrological modelling approach to analyse the impact of land cover changes on the water resources of a mesoscale humid tropical catchment. First, a change detection analysis of Landsat/ ETM + satellite images wascarried out to quantify land cover changes of the mesoscale Gumbasa River catchment in Central Sulawesi, Indonesia. There-after the distributed hydrological model WASIM-ETH was calibrated and validated for the current Landsat/ ETM + scene.The historical Landsat/ ETM + scene was integrated for the hydrological model application as a historical land cover scenario.Further hypothetical total-change scenarios were carried out. The results of the hydrological model scenario application clearlydemonstrate a strong relationship between deforestation rates and increasing discharge variability. Especially a significant increase of high water discharges was simulated for the applied scenarios. With regard to the high deforestation rates of the research catchment, one can expect further changes of the water balance.