The Making of a Tibetan Landscape: Identification of Parameters, Actors and Dynamics of the Kobresia pygmaea pastoral ecosystems - Module 4 and 5: Vegetation dynamics, biomass allocation and water consumption of Kobresia as a function of grazing and envir

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The Kobresia pygmaea pastures are the world's largest 'alpine' ecosystem extending over 450 000km2 in the south-eastern Tibetan highlands; they are subject to rapid land use and climate change. The first 1.5-year phase of the plant ecological project in the Kobresia consortium within TiP gave conclusive evidence that Kobresia pastures at montane elevations are rapidly replaced by other grasslands under grazing exclusion, while high-alpine pastures respond more slowly due to slower growth. Water shortage limits Kobresia growth even in its distribution centre, enhanced by very high evaporative losses as observed in lysimeter measurements. Nutrient (N) shortage seems to be also important. Sexual regeneration is rare in K. pygmaea due to high environmental stresses but also unexpectedly pronounced seed dormancy. Newly established microsatellites allowed DNA-based mapping of potential clones in the field; these are present but seem to cover not more than 0.25 m2. We apply for a continuation of the successful research in order to cover another 3 years of Vegetation monitoring at the Kema core site (and at Lhasa, Reting und Qinghai). Additionally, we want to investigate the consequences of altered rainfall, temperature and N supply experimentally. In a Joint experiment with the soil group, we manipulate rainfall by a specially designed gutter roof construction, and test the interaction of rainfall decrease/increase and N fertilization in its effect on Vegetation composition, productivity and hydrology. The lysimeter study is supplemented by a soil warming and cooling experiment using heat pipes. The consequences of overgrazing will be investigated by a clipping experiment. The data on vegetation composition, productivity and hydrology will be supplemented by population ecological studies. Investigations on the age of pastoralism are continued using vegetation record data, data of grazing indicator pollen types and pollen clumps.