The Kobresia pygmaea ecosystem of the Tibetan highlands - Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet.
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2018-01
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With 450,000 km^2 Kobresia (syn. Carex) pygmaea dominated pastures in the eastern Tibetan highlands are the world's largest pastoral alpine ecosystem forming a durable turf cover at 3000–6000 m a.s.l. Kobresia's resilience and competitiveness is based on dwarf habit, predominantly below-ground allocation of photo assimilates, mixture of seed production and clonal growth, and high genetic diversity. Kobresia growth is co-limited by livestock-mediated nutrient withdrawal and, in the drier parts of the plateau, low rainfall during the short and cold growing season. Overstocking has caused pasture degradation and soil deterioration over most parts of the Tibetan highlands and is the basis for this man-made ecosystem. Natural autocyclic processes of turf destruction and soil erosion are initiated through polygonal turf cover cracking, and accelerated by soil-dwelling endemic small mammals in the absence of predators. The major consequences of vegetation cover deterioration include the release of large amounts of C, earlier diurnal formation of clouds, and decreased surface temperatures. These effects decrease the recovery potential of Kobresia pastures and make them more vulnerable to anthropogenic pressure and climate change. Traditional migratory rangeland management was sustainable over millennia, and possibly still offers the best strategy to conserve and possibly increase C stocks in the Kobresia turf.
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Miehe, Georg, Per-Marten Schleuss, Elke Seeber, Wolfgang Babel, Tobias Biermann, Martin Braendle, Fahu Chen, Heinz Coners, Thomas Foken, Tobias Gerken, Hans-F Graf, Georg Guggenberger, Silke Hafner, Maika Holzapfel, Johannes Ingrisch, Yakov Kuzyakov, Zhongping Lai, Lukas Lehnert, Christoph Leuschner, Xiaogang Li, Jianquan Liu, Shibin Liu, Yaoming Ma, Sabine Miehe, Volker Mosbrugger, Henry J. Noltie, Joachim Schmidt, Sandra Spielvogel, Sebastian Unteregelsbacher, Yun Wang, Sandra Willinghöfer, Xingliang Xu, Yongping Yang, Shuren Zhang, Lars Opgenoorth, and Karsten Wesche. "The Kobresia pygmaea ecosystem of the Tibetan highlands - Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet.." Science of the Total Environment 648 (January 2019): 754-771. DOI:10.1016/j.scitotenv.2018.08.164.