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Polyploidy is a fundamental mechanism in evolution, but is hard to detect in taxa with agmatoploidy or aneuploidy. We tested whether a combination of chromosome counting, microsatellite analyses and flow cytometric measurements represents a suitable approach for the detection of basic chromosome numbers and ploidy in Kobresia (Cyperaceae). Chromosome counting resulted in 2n = 64 for Kobresia pygmaea and K. cercostachys, 2n = 58 and 64 for K. myosuroides, and 2n = 72 for K. simpliciuscula. We characterized eight microsatellite loci for K. pygmaea, which gave a maximum of four alleles per individual. Cross-species amplification was tested in 26 congeneric species and, on average, six of eight loci amplified successfully. Using flow cytometry, we confirmed tetraploidy in K. pygmaea. Basic chromosome numbers and ploidy were inferred from chromosome counts and the maximum number of alleles per locus. We consider the basic numbers as x = 16 and 18, with irregularities derived from agmatoploidy and aneuploidy. Across all Kobresia taxa, ploidy ranged from diploid up to heptaploid. The combination of chromosome counts and microsatellite analyses is an ideal method for the determination of basic chromosome numbers and for inferring ploidy, and flow cytometry is a suitable tool for the identification of deviating cytotypes.

The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.

The non-equilibrium concept of rangeland dynamics predicts that the potential for grazing-induced degradation is low in rangelands with relatively variable precipitation. To date, evidence in support of the non-equilibrium concept has been inconsistent. Using a standardized protocol, including a newly developed global map of rainfall variability, we reviewed the incidence of degradation in relation to rainfall variability across 58 published studies. We distinguished between (1) zonal degradation (i.e., degradation independent of water and key resources), (2) degradation in the presence of key resources, and (3) degradation in the presence of water. For studies not affected by proximity to permanent water or key resources, we found strong support for the non-equilibrium concept for rangelands. Zonal degradation was absent at CV (coefficient of variation) values above 33%, which has been proposed as a critical threshold. Grazing degradation was almost entirely restricted to areas with relatively stable annual precipitation as expressed by a low CV, or to rangelands with key resources or water points nearby. To better understand rangeland dynamics, we recommend that future studies use globally comparable measures of degradation and rainfall variability. Our work underlines that rangelands with relatively stable rainfall patterns, and those with access to water or key resources, are potentially vulnerable to degradation. Grazing management in such areas should incorporate strategic rest periods. Such rest periods effectively mimic natural fluctuations in herbivore populations, which are a defining characteristic of non-degraded rangelands occurring under highly variable precipitation regimes.

Eleven plant communities of the central Tibetan ecotone (31°20′–33°00′N/89°00′–92°10′E) between the Kobresia pygmaea grazing pastures of the eastern highlands and the open short grass steppe with cushion plants (“Alpine Steppe”) of the north-western highlands have been described on the basis of 189 plot-based floristically complete vegetation records. In parallel, remote sensing techniques distinguish four main land-use cover types. Our hypotheses are: (1) The plant communities of the central Tibetan highlands are grazing-adapted and resilient to degradation. (2) In contrast to grazing resilient plant functional types, the turf cover of the K. pygmaea pastures and the Kobresia schoenoides wetlands is degradable through desiccation, periglacial processes, soil-dwelling small mammals and livestock. Five grazing-related plant functional traits are introduced. Grazing tolerance is the prevalent functional type. Species with no specific protection against grazing make up not more than 6% of the total cover. Unpalatable plants cover up to 8%. Only the azonal K. schoenoides swamps – the indispensable winter grazing reserve – have been widely degraded and depleted by 75%, being replaced by Carex sagaensis grazing pastures. It can be foreseen that governmental policy of sedentarisation of nomads will lead to reduced grazing mobility and degradation of winter grazing reserves.

Stipa capillata L. (Poaceae) is a rare grassland species in Central Europe that is thought to have once been widespread in post-glacial times. Such relict species are expected to show low genetic diversity within populations and high genetic differentiation between populations due to bottlenecks, long-term isolation and ongoing habitat fragmentation. These patterns should be particularly pronounced in selfing species. We analysed patterns of random amplified polymorphic DNA (RAPD) variation in the facultatively cleistogamous S. capillata to examine whether genetic diversity is associated with population size, and to draw initial conclusions on the migration history of this species in Central Europe. We analysed 31 S. capillata populations distributed in northeastern, central and western Germany, Switzerland and Slovakia. Estimates of genetic diversity at the population level were low and not related to population size. Among all populations, extraordinarily high levels of genetic differentiation (amova: fST = 0.86; Bayesian analysis: ?B = 0.758) and isolation-by-distance were detected. Hierarchical amova indicated that most of the variability was partitioned among geographic regions (59%), or among populations between regions when the genetically distinct Slovakian populations were excluded. These findings are supported by results of a multivariate ordination analysis. We also found two different groups in an UPGMA cluster analysis: one that contained the populations from Slovakia, and the other that combined the populations from Germany and Switzerland. Our findings imply that S. capillata is indeed a relict species that experienced strong bottlenecks in Central Europe, enhanced by isolation and selfing. Most likely, populations in Slovakia were not the main genetic source for the post-glacial colonization of Central Europe.

We assessed presence/absence prediction of plant species and communities in a southern Mongolian mountain range from geospatial data using a randomized sampling approach. One hundred randomized vegetation samples (3×3 m) were collected within the 2×2 km summit region of the Dund Saykhan range, which forms part of the core zone of the Gobi Gurvan Saykhan National Park in arid southern Mongolia. Using logistic regression, habitat preference models for all abundant species (n=52) and communities (n=5) were constructed; predictors were derived from Landsat 5 imagery and a digital elevation model. Nagelkerkes r2 was used for an initial data mining, and all significant models were validated by splitting the data and using one half for accuracy assessment based on the AUC (Area Under the receiver operating characteristic Curve)-values. Significant models could be built for half of the species. Altitude proved to be the most important predictor followed by variables derived from Landsat data. The clear altitudinal distribution patterns most definitely reflect precipitation; overall biodiversity in this arid environment is widely controlled by moisture availability. The chosen approach may prove valuable for applied studies wherever spatial data on species distributions are required for conservation efforts.

Question What are the trends and patterns in the application of ordination techniques in vegetation science since 1990? Location Worldwide literature analysis. Methods Evaluation of five major journals of vegetation science; search of all ISI-listed ecological journals. Data were analysed with ANCOVAs, Spearman rank correlations, GLMs, biodiversity indices and simple graphs. Results The ISI search retrieved fewer papers that used ordinations than the manual evaluation of five selected journals. Both retrieval methods revealed a clear trend in increasing frequency of ordination applications from 1990 to the present. Canonical Correspondence Analysis was far more frequently detected by the ISI search than any other method. Applications such as Correspondence Analysis/Reciprocal Averaging and Detrended Correspondence Analysis have increasingly been used in studies published in "applied" journals, while Canonical Correspondence Analysis, Redundancy Analysis and Non-Metric Multidimensional Scaling were more frequently used in journals focusing on more "basic" research. Overall, Detrended Correspondence Analysis was the most commonly applied method within the five major journals, although the number of publications slightly decreased over time. Use of Non-Metric Multidimensional Scaling has increased over the last 10 years. Conclusion The availability of suitable software packages has facilitated the application of certain techniques such as Non-Metric Multidimensional Scaling. However, choices of ordination techniques are currently less driven by the constraints imposed by the software; there is also limited evidence that the choice of methods follows social considerations such as the need to use fashionable methods. Methodological diversity has been maintained or has even increased over time and reflects the researcher's need for diverse analytical tools suitable to address a wide range of questions.

Spatially restricted gene flow and resulting spatial genetic structure are generally considered as being the primary controlling factors in the dynamics of biparental inbreeding depression in a wide range of plant species. However, wind-pollinated angiosperm trees have not been studied adequately in this respect. The present study analyses the relationships among parental genetic similarity, outcrossing distances, progeny vigour and mortality in Polylepis australis (Rosaceae), a wind-pollinated treeline species endemic to Argentina. We investigated whether spatial genetic structuring occurs in anthropogenically fragmented P. australis woodlands of the Córdoba Mountains. We also performed a controlled crossing experiment using pollen collected from different distances. Genetic variability (using RAPD-PCR), vigour (N-metabolism capacity) and mortality of the resulting progeny were contrasted with progeny from unmanipulated flowers. We found a continuous decrease in parental genetic similarity with spatial distance among mates and an increase in N-metabolism capacity in the progeny produced from pollen at increasing distances, as well as a very high mortality of seedlings resulting from short-distance crosses. Additionally, our results suggest that there is still fragment connectivity in P. australis through long-distance pollen-mediated gene flow.

Species of Mediterranean vegetation are known to regenerate directly after fire. The phenomenon of autosuccession (direct regeneration) has been found to be often combined with an increase of species richness during the first years after fire due to the high abundance of short-lived herbaceous plants facilitated by plentiful nutrients and light. The high degree of vegetation resilience, which is expressed in terms of autosuccession, has been explained by the selective pressure of fire in historic times. According to existing palaeoecological data, however, the Pinus halepensis forests in the Ricote Mountains (Province of Murcia, SE Spain) did not experience substantial fire impact before the presence of man nor are they especially fire-prone today. Therefore, we studied post-fire regeneration to find out if direct succession is present or if species from pre-fire vegetation are absent during the post-fire regeneration stages. Patterns of succession were deduced from observations made in sample plots on sites of a known regeneration age as well as in adjacent unburnt areas. The results of the vegetation analyses, including a Detrended Correspondence Analysis, indicate that Pinus halepensis forest regeneration after fire resembles autosuccession. As regards the presence of woody species, there is a high percentage similarity on north (83%) and south (70%) facing slopes during the first year after fire vs. reference areas which is due, for example, to direct regeneration of the resprouting Quercus coccifera or seeders like Pinus halepensis or Fumana laevipes. However, if herbaceous species are included in the comparison, the similarity on north-facing sites decreases (to 53%) with the presence of additional species, mainly ruderals like Anagallis arvensis or Reseda phyteuma, and even woody species on the burnt plots. This effect indicates "enhanced autosuccession", which was not found on south-facing sites where overall species richness was very high irrespective of th

© 2018 With 450,000 km2 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.

© 2018 Elsevier Ltd Based on fossil organism remains including plant macrofossils, charcoal, pollen, and invertebrates preserved in syngenetic deposits of the Batagay permafrost sequence in the Siberian Yana Highlands, we reconstructed the environmental history during marine isotope stages (MIS) 6 to 2. Two fossil assemblages, exceptionally rich in plant remains, allowed for a detailed description of the palaeo-vegetation during two climate extremes of the Late Pleistocene, the onset of the last glacial maximum (LGM) and the last interglacial. In addition, altogether 41 assemblages were used to outline the vegetation history since the penultimate cold stage of MIS 6. Accordingly, meadow steppes analogue to modern communities of the phytosociological order Festucetalia lenensis formed the primary vegetation during the Saalian and Weichselian cold stages. Cold-resistant tundra-steppe communities (Carici rupestris-Kobresietea bellardii) as they occur above the treeline today were, in contrast to more northern locations, mostly lacking. During the last interglacial, open coniferous woodland similar to modern larch taiga was the primary vegetation at the site. Abundant charcoal indicates wildfire events during the last interglacial. Zoogenic disturbances of the local vegetation were indicated by the presence of ruderal plants, especially by abundant Urtica dioica, suggesting that the area was an interglacial refugium for large herbivores. Meadow steppes, which formed the primary vegetation during cold stages and provided potentially suitable pastures for herbivores, were a significant constituent of the plant cover in the Yana Highlands also under the full warm stage conditions of the last interglacial. Consequently, meadow steppes occurred in the Yana Highlands during the entire investigated timespan from MIS 6 to MIS 2 documenting a remarkable environmental stability. Thus, the proportion of meadow steppe vegetation merely shifted in response to the respectively prevai

© Author(s) 2014. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.

© Author(s) 2014. The Tibetan Plateau has a significant role with regard to atmospheric circulation and the monsoon in particular. Changes between a closed plant cover and open bare soil are one of the striking effects of land use degradation observed with unsustainable range management or climate change, but experiments investigating changes of surface properties and processes together with atmospheric feedbacks are rare and have not been undertaken in the world's two largest alpine ecosystems, the alpine steppe and the Kobresia pygmaea pastures of the Tibetan Plateau. We connected measurements of micro-lysimeter, chamber, 13C labelling, and eddy covariance and combined the observations with land surface and atmospheric models, adapted to the highland conditions. This allowed us to analyse how three degradation stages affect the water and carbon cycle of pastures on the landscape scale within the core region of the Kobresia pygmaea ecosystem. The study revealed that increasing degradation of the Kobresia turf affects carbon allocation and strongly reduces the carbon uptake, compromising the function of Kobresia pastures as a carbon sink. Pasture degradation leads to a shift from transpiration to evaporation while a change in the sum of evapotranspiration over a longer period cannot be confirmed. The results show an earlier onset of convection and cloud generation, likely triggered by a shift in evapotranspiration timing when dominated by evaporation. Consequently, precipitation starts earlier and clouds decrease the incoming solar radiation. In summary, the changes in surface properties by pasture degradation found on the highland have a significant influence on larger scales.