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The Dzungarian Gobi (DzG), one of 16 phytogeographical regions in the country, is located in the southwestern part of Khovd province in western Mongolia. It comprises some of Mongolia’s largest reserves, namely the Great Gobi B Strictly Protected Area and the National Park Bulgan gol-Ikh Ongog. We conducted a comprehensive survey of the area’s floristic diversity between 2009 and 2019 by collecting vascular plants from different vegetation types in various seasons. In addition, we critically checked relevant published literature and material from the herbaria ALTB, GLM, GWF, HAL, KHU, LE, MW, NS, OSBU, UBA, and UBU to determine the occurrence of vascular plant species in the DzG region. Based on our collection data, a comprehensive checklist of DzG’s flora was compiled, representing 913 vascular plant taxa (including 34 subspecies and one variety) belonging to 329 genera and 70 families. Twenty-one taxa were newly found in the DzG region. We also investigated the conservation status of all species noted, and 19 endemic plants and 96 threatened species, including six critically endangered, 26 endangered, 57 vulnerable, and seven near threatened plants were recognized in this region. Eight rare species were newly assessed according to regional conservation status based on GeoCat and IUCN. The richest plant families found were Asteraceae (153 species), Fabaceae (77 species), Amaranthaceae (69 species), and Poaceae (68 species). Several uncertain endemic and non-endemic plants remain still discussion, such as Papaver baitagense and Rosa baitagensis; thus, further studies are needed on their taxonomic and conservation status. For each taxon, we provide its distribution in the region, elevation range, voucher number, and additional references. Finally, we analyzed species hotspots of DzG, based on three different plant species richness criteria: i. all recorded species, ii. endemic species, and iii. threatened species using our georeferenced records. The most diverse hotspot area in DzG is the Baitag Bogd Mountain area, which comprises the highest species number of all three richness criteria.

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The Selenge basin contributes approximately 50% of the total inflow into Lake Baikal and is thus of high significance for the regional hydrological regime. Our study was conducted in the upper reaches of the basin, where the Selenge river and its tributaries flow through the Mongolian forest-steppe. Monthly and maximum runoff, precipitation, and air temperature data from 12 gauging stations collected between 1978 and 2015 were analyzed to characterize the hydrological regime response to climate change. Concomitant with rising temperatures and increased potential evaporation, river runoff in the Mongolian part of the Selenge basin has decreased from the first interval (1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995) of our study period compared with the consecutive interval from 1996 to 2015. The decrease in runoff throughout the study area was most likely caused by an increase in potential evapotranspiration (and not reduced precipitation or land use changes) for both summer rainfall-and snowmelt-dominated rivers. Annual maximum runoff has also strongly decreased suggesting that reduced flooding is a contemporary threat for Mongolia's riverine ecosystems, probably causing the replacement of wetland and mesic habitats.

The Valley of the Great Lakes in western Mongolia is a unique ecosystem comprising a wide variety of terrestrial and aquatic habitats. Relatively little is known about the long-term climate history of the area or the relative impact of changes in climate and land use in the region. Tree-ring records have established an understanding of regional temperature fluctuations; however, the few records of moisture balance from Mongolia offer little insight into potential changes in the precipitation-to-evaporation balance in the region with warming temperatures. Modern and paleoclimatic records from across arid Central Asia show substantial temporal and spatial variability in the correlation between temperature and moisture availability and climate models are inconsistent in predictions for future changes with continued warming. In order to refine the understanding of moisture balance in the region, we developed six diatom-inferred records of lake salinity between 200 and 2000 years in length, demonstrating a negative correlation between temperature and effective moisture (warm-dry and cool-wet conditions) over most of this time period. In addition to climate warming, Mongolian grasslands have seen substantial human impacts over the last several decades. Recent core records show evidence of eutrophication and must be interpreted carefully to understand the individual and combined impacts of climate and land use on sedimentary records and the potential for human—environment interactions to confound inferences about climate changes.

An improved knowledge of long-term climatic variations over the Altai-Dzungarian region will increase our understanding of the current climate and help to predict the effects of global warming on future water availability in this region. We sampled 77 Larix sibirica Ledeb. trees at upper and lower treelines in the southern Mongolian Altai mountains and reconstructed temperature and precipitation for longer periods than previous studies from this area. We reconstructed mean June-July air temperatures for the period 1402-2012 and June-December precipitation for the period 1569-2012 based on tree ring width chronologies. The temperature and precipitation reconstructions explain 39.7 and 41.3% of the respective station observation variance during the common periods. The precipitation reconstruction shows alternating wet and dry conditions during the Little Ice Age (1580-1874) followed by more stable conditions until a late 20th century wetting. The temperature reconstruction attributes the warmest period to the 20th century, which follows cooler periods related to volcanic and low solar activities during the Little Ice Age. Long-term climatic variation and change over the Altai-Dzungarian region is inferred from the analysis of the combined temperature and precipitation reconstructions for the common period 1580-2012. Accordingly, this region has become warmer since 1875 as the number of warm/moist and warm/dry years increased by 2 and 14%, respectively, while the number of cool/moist and cool/dry years both decreased by 8% compared to the Little Ice Age. Our findings also reveal a late 20th century cool and wet period, which has also been observed across other mountainous areas of China and Nepal. This period was most probably caused by volcanic-induced cooling and coincided positive phases of the Arctic Oscillation and North Atlantic Oscillation promoting an intensified subtropical westerly jet and a positive summer rainfall anomaly over the Altai-Dzungarian region.