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Most landslides in Qinghai-Tibet Plateau take place in the Quaternary strata. Reasonable deformation mechanism, analyses method and controlling measures are proposed to treat colluvial landslides in this paper. Combined with the regional geological conditions of a colluvial landslide located at Road S101 Line of Qinghai Province, distinctive influencing factors were analyzed, including adverse physical and mechanical properties, geometrical structure, coupled fluid and thermal process. Slope stability was simulated by finite difference method. Displacement and shear strain in the lower part of sliding body are both higher than the upper part in saturated condition, consistent with the actual sliding characteristics. According to the geological comprehensive analyses and numerical simulation, the deformation mechanism, temporal and spatial evolutionary processes were summarized. The results show that freeze-thaw cyclic process of stagnant water during winter and spring make shallow deposits creep continuously and slide ultimately. Saturated condition caused by rainstorm in summer or autumn makes the slope slide integrally, and draws the mudstone at back to slide subsequently. The suitability and practical feedback of various kinds of controlling measures applied to colluvial landslides in cold regions were discussed. Micropile has significant elastic flexibility and unloading ability, and so can adapt to the mechanical change and sliding process of slope during freeze-thaw process. Both practical application and numerical calculation indicate that micropile is an appropriate choice against colluvial landslides in Qinghai-Tibet Plateau. [ABSTRACT FROM AUTHOR]

A new genus of Compositae, Shangwua, is described to accomodate all species formerly placed in Saussurea sect. Jacea. This genus is distinct from the other genera of tribe Cardueae in its unique combination of states of characters including involucral bracts, receptacle, paleae, anther, style, achene and pappus. Phylogenetic analyses based on molecular data suggest that this new genus belongs to the Xeranthemum group, a lineage of the Carduinae that diversified early, with only distant relationships to Saussurea and related genera. The genus Shangwua consists of three species occurring in the Qinghai-Tibetan Plateau and Himalayas. [ABSTRACT FROM AUTHOR]

Background: Most empirical studies to date have suggested that alpine plants in the central Qinghai-Tibetan Plateau (QTP) originated from the south-eastern QTP. However, previous phylogeographcial analysis of Potentilla fruticosa suggested that it diversified in the central QTP, which has also been assumed to have been a glacial refugium, and expanded to the north-eastern regions during the mid-Holocene period. Aim: We reappraise this claim in the light of information acquired from sampling, haplotyping and analysing additional populations. Methods: We sequenced the chloroplast trnT-L intergenic spacer of 346 individuals collected from 52 populations. We reconstructed phylogenetic relationships among haplotypes through Bayesian and Network analysis, and used several methods for demographic analysis. Results: Some common and highly divergent haplotypes were distributed in the central, western and south-eastern QTP. Mismatch and other population genetic analyses applied to our data suggested that a distinct range expansion had occurred between approximately 30,000 and 325,000 years ago (kya). Conclusions: Besides the possible postglacial expansion in the north-eastern QTP, our results further suggested that the range of the species radically expanded across the whole Plateau before the last glacial maximum (around 18 kya) and the south-eastern, western and central QTP regions had together provided important refugia during recent glacial stages. These findings, in contrast to the previous conclusions, highlight the importance of adequate sampling strategies in phylogeographical studies. [ABSTRACT FROM AUTHOR]

Aim Most species of temperate regions are believed to have shifted to lower latitudes or elevations during the glacial periods of the Quaternary. In this study we test whether this phylogeographic assumption is also true for the plateau zokor ( Eospalax baileyi), a fossorial rodent endemic to the climate-sensitive Qinghai–Tibetan Plateau (QTP), which ranges in elevation from 2600 to 4600 m. Location The QTP of western China. Methods Phylogeographic analyses were conducted based on the mitochondrial cytochrome b gene sequences of 193 individuals from 20 populations over the entire range of the species. Results A total of 54 haplotypes identified in the present study clustered into four geographically correlated clades located in the interior of the QTP (clade A) and at the plateau edge (B, C and D). Molecular calibrations suggest that the interior plateau (A) and plateau-edge (B–D) clades diverged at 1.2 Ma and that the three plateau-edge clades diverged between 0.85 and 0.80 Ma. These estimates are concordant with diastrophism and glaciation events in the QTP. Coalescent tests rejected both the hypothesis that all current populations originated from a single refugium at a low elevation during the Last Glacial Maximum (LGM) and the hypothesis that the two lineages diverged during the LGM. The tests instead supported the hypothesis that there were four refugia during the LGM, and that the four clades diverged prior to the late Pleistocene. Main conclusions Our results suggest that Quaternary diastrophisms and glaciations repeatedly promoted allopatric divergence of the plateau zokor into geographical clades, and that these regional clades subsequently persisted at high elevations, rather than migrating to the low-elevation plateau edge during subsequent glacial ages. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that geological or climatic events in the past triggered the radiative diversification of both animals and plants on islands as well as continents. The Qinghai–Tibetan Plateau (QTP) has been extensively uplifted since the Miocene, but there is little information on possible links between these events and biological diversification in this and adjacent regions. Partly to explore such links, we have examined the diversification of Saussurea (Asteraceae: Cardueae), a species-rich genus that is mostly endemic to QTP, but also occurs in arid highlands elsewhere in the Northern Hemisphere. The phylogenetic analyses were conducted on the basis of the nuclear (internal transcribed spacer, ITS) and plastid ( trnL-F and psbA-trnH) sequences from 55 species, representing 19 sections from all six subgenera of Saussurea, and species from 15 genera of the Cardueae. The results suggest that the currently circumscribed genus Saussurea ( s.l.) is a polyphyletic group and that five sections should be excluded from the genus. Samples from the other 14 sections (representing five subgenera) clustered as a monophyletic group (here designated the Saussurea s.s. lineage, SSSL) with high statistical support. However, none of the analyses (nuclear, plastid or combined) resolved SSSL's infrageneric phylogeny, and the parallel clades of the lineage indicate that island-like adaptive radiation occurred. Furthermore, this radiation appears to have occurred 14–7 Mya, during the period of the major uplift events of QTP. Thus, our results support the hypothesis that geological events may play important roles in driving biological diversification through continental radiation. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 893–903. [ABSTRACT FROM AUTHOR]

Juniperus przewalskii (Cupressaceae) is a dominant tree species endemic to the northeast Qinghai-Tibetan Plateau. This species plays an important role in maintaining the arid ecosystem in this region. However, natural distributions of this species have been declined. In order to develop effective conservation methods, it is important to know the distribution of the genetic diversity within and among populations. In this study, we developed nine new microsatellite loci for this species. We used the combining biotin capture method to enrich AG/CT/AC/GGT microsatellites. The polymorphisms of each locus were further assessed in 12 individuals from four geographically distant populations. The number of alleles per locus varied from three to six and expected heterozygosity ranged from 0.58 to 0.70. These loci together provide a useful tool to investigate the genetic diversity of this species. In addition, all markers have been crossly checked in the other four congeneric species. [ABSTRACT FROM AUTHOR]