1. Martin-Benito D, Ummenhofer CC, Köse N, et al. Tree-ringreconstructed May–June precipitation in the Caucasus since 1752 CE . ClimateDynamics, 2016: 1-17. The Caucasus region experiences recurrent droughts thataffect natural vegetation and the agriculture-based economies of severalcountries. Because meteorological records are in general scarce and of shorttimespan, little is known about the magnitude and frequency of past climatevariability. Despite the recent increase of climate reconstructions for partsof Eurasia, no study has focused on past hydroclimate variability in theCaucasus. Here, we use a multispecies network of tree-ring width chronologiesfrom the Lesser Caucasus to develop the first precipitation reconstruction forthe region back to 1752 CE. Despite the high annual precipitation in theregion, our reconstruction accounted for 51.2 % of the variability in May–Juneprecipitation from 1930 to 2001. In comparison with reconstructions in theeastern Mediterranean, our new reconstruction revealed important and distinctdrought periods and pluvials. Previous winter North Atlantic Oscillation (NAO),and spring East Atlantic/Western Russia (EA/WR) and North Sea Caspian patternsare likely key drivers of May–June precipitation in the Caucasus and Anatolia.NAO appeared to negatively affect rainfall low-frequency variability whileeffects of EA/WR were more apparent at the interannual timescales. We also showa potential positive effect of Black Sea surface temperatures on May–Juneprecipitation. In the Caucasus, May–June represents the period of major watersupply in semi-arid areas and the period with the highest potential of waterscarcity in mesic areas. It is also a period of potential catastrophic floodevents. Thus, changes to the precipitation regime during this season will becritical to both human and natural systems of the Caucasus region. 2. Büntgen U, Myglan V S,Ljungqvist F C, et al. Cooling andsocietal change during the Late Antique Little Ice Age from 536 to around 660AD . Nature Geoscience, 2016. Climatic changes during the first half of the Common Erahave been suggested to play a role in societal reorganizations in Europe andAsia. In particular, the sixth century coincides with rising and fallingcivilizations, pandemics, human migration and political turmoil. Ourunderstanding of the magnitude and spatial extent as well as the possiblecauses and concurrences of climate change during this period is, however, stilllimited. Here we use tree-ring chronologies from the Russian Altai and EuropeanAlps to reconstruct summer temperatures over the past two millennia. We find anunprecedented, long-lasting and spatially synchronized cooling following acluster of large volcanic eruptions in 536, 540 and 547 AD, which was probablysustained by ocean and sea-ice feedbacks, as well as a solar minimum. We thusidentify the interval from 536 to about 660 AD as the Late Antique Little IceAge. Spanning most of the Northern Hemisphere, we suggest that this cold phasebe considered as an additional environmental factor contributing to theestablishment of the Justinian plague, transformation of the eastern RomanEmpire and collapse of the Sasanian Empire, movements out of the Asian steppeand Arabian Peninsula, spread of Slavic-speaking peoples and politicalupheavals in China. 3. Haldon J. History: Cooling and societal change . NatureGeoscience, 2016. The rise and fall of civilizations over the past twomillennia was set against a backdrop of climate change. High-resolution climaterecords evince a link between societal change and a period of cooling in thesixth and seventh centuries. 4. Feng, M., Wang, Q., Hao, Q.,Yin, Y., Song, Z., Wang, H., Liu, H. (2016). Determinants of soil erosion during the last 1600years in theforest–steppe ecotone in Northern China reconstructed from lacustrine sediments .Palaeogeography, Palaeoclimatology, Palaeoecology. Wind erosion of soil in northern China contributes to theenvironment of East Asia and even the Northern Hemisphere. It is commonlythought that human-induced grassland degradation determines soil erosion in thesemi-arid steppe region. In this study, we revealed determinants of soilerosion during the last ~ 1600 years through analyzing lacustrine sediment fromHuangqihai Lake in this region. Our results showed soil erosion indicated bysediment particle size was enhanced during three periods: 1570–1330 cal. yr. BPwith warm and dry climate, 1250–1000 cal. yr. BP with warm and wet climate, and470–150 cal. yr. BP with cold and dry climate. The common feature of vegetationregimes for enhanced soil erosion was replacement of forest by steppe,suggesting that decline in vegetation cover from forest to steppe, which wasattributed to climatic changes, might lead to enhancement in soil erosion. Thetrend of historical soil erosion did not match the steady increase inhistorical human population in China and the very short history of massivecultivation in southern Inner Mongolia. In summary, our results supportednature- rather than human-dominated soil erosion in the semi-arid steppe regionin north China during the last 1600 years. 5. Piper, F. I., Viñegla, B.,Linares, J. C., Camarero, J. J., Cavieres, L. A., Fajardo, A. (2016). Mediterranean and temperate treelines arecontrolled by different environmental drivers . Journal of Ecology. Thegrowth limitation hypothesis (GLH) is the most accepted explanation fortreeline formation, but it has been scarcely examined in Mediterraneantreelines, which are located at lower elevations than temperate treelines. TheGLH states that low temperature is the ultimate environmental driver fortreeline formation, constraining C-sinks (i.e. tissue formation) more thanC-sources. The GLH predicts similar or increasing (but not decreasing)non-structural carbohydrate (NSC) concentrations with elevation throughout thecourse of the growing season. We hypothesized that elevational trends in growthand NSC in Mediterranean regions are not determined by only low temperature. We testedthe GLH by examining the mean annual basal area and NSC concentrations indeveloping (new twigs) and ripened tissues (branch, stem) of trees growing atthree elevations in three Mediterranean and three temperate treelines in theChilean southern Andes (33oS, Kageneckia angustifolia, 36oS, 40oS, and 46oS,Nothofagus pumilio) and in Spain (36oN, Pinus sylvestris, 42oN, P. uncinata).Samples for NSC were taken at the onset of summer and autumn, which representperiods of contrasting drought intensities in Mediterranean regions. Treegrowth decreased significantly with elevation in temperate treelines but not inMediterranean treelines. In Mediterranean treelines, new twig NSCconcentrations increased significantly with elevation in the early summer butnot in the early autumn. In temperate treelines, in contrast, no elevational orseasonal variation (or interaction between them) was observed in new twig NSCconcentrations. The NSC concentrations of the branches and stems from bothclimates showed no elevational trends. The soluble sugars’ NSC fractionincreased over the season in Mediterranean treelines and decreased in temperatetreelines. Synthesis. Although we found support for the growthlimitation hypothesis (GLH) in temperate and Mediterranean treelines, our studyshows that the tree growth and C balance in Mediterranean treelines are notcontrolled by low temperature alone. We suggest that environmental factorsother than temperature explain the lower global elevation of Mediterraneantreelines when compared to temperate treelines.
soil erosion is not only an important problem in local and basin level,but aslo a global environmental problem. all of people unite, do our best to deal with soil erosion
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