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

青藏高原东南部的矮嵩草草场是世界上最大的“高山”生态系统，面积超过45万平方公里；他们受到快速的土地利用和气候变化的影响。TiP内的Kobresia联盟植物生态项目前1.5年的研究结果表明，高山海拔的Kobresia草场在禁牧条件下被其他草场迅速取代，而高寒草场由于生长速度较慢，反应较慢。水资源短缺限制了Kobresia的增长，甚至在其配送中心也是如此，在蒸渗仪测量中观察到的非常高的蒸发损失增强了这种增长。养分(N)短缺似乎也很重要。由于高环境胁迫，性再生在pygmaea中是罕见的，但也出乎意料地宣布种子休眠。新建立的微型卫星允许在现场对潜在的克隆进行基于dna的制图；这些是存在的，但似乎不超过0.25平方米。我们申请继续这项成功的研究，以便在克玛核心站点（以及拉萨、热亭和青海）进行另外3年的植被监测。此外，我们希望通过实验研究降雨、温度和氮供应变化的后果。在与土壤组的联合试验中，我们通过特殊设计的沟槽屋面结构来控制降雨，并测试降雨量减少/增加与氮肥的交互作用对植被组成、生产力和水文的影响。在溶血计研究的基础上，还进行了热管土壤增温降温实验。过度放牧的后果将通过修剪试验进行调查。关于植被组成、生产力和水文的数据将由人口生态学研究加以补充。利用植被记录资料、放牧指示花粉类型资料和花粉团块资料，继续对放牧时代进行调查。

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.