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The dwarf forms of Stenopoa (height 5-15 cm) which are common in alpine belt of the Pan-Himalayas, represent one of the most problematic groups in the genus. Ten dwarf species of Stenopoa have been recorded for the area under consideration: P. attenuata Trin, P.glauca Vahl, P. litvinoviana Ovcz., P. albertii Regel, P. koelzii Bor, P. lahulensis Bor, P. poophagorum Bor, P. arnoldii Melderis, P. mustangensis Rajb., and P. roemeri Bor. At least 6 other taxa have been mentioned as synonyms of these species. Comparative examination of many specimens of this group using a morphogeographic approach supports recognition of 10 species, which belong to 3 species aggregates: aggr. P. attenuata, aggr. P. glauca and aggr. P. albertii. Taxa in aggr. P. albertii are thought to have originated from hybridization between species of aggr. P. attenuata and aggr. P. glauca. Our research leads us to recommend recognizing P. roemeri, P. koelzii, P. mustangensis, P. rangkulensis Ovcz., P. scabriculmis N.R. Cui, P. tshuensis (Serg.) Olonova and P. indattenuata Keng as species; three of them have been recorded from the Pan-Himalayas. Poa koelzii is included in aggr. P. attenuata because of its similarity to that species. A key for identifying the taxa is presented. One new combination, Poa scabriculmis subsp. kunlunensis (N.R. Cui) Olonova, is presented. [ABSTRACT FROM AUTHOR]

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., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)