Concerns have been raised about the negative impacts of global warming on the hydrological climate change and ecosystems of Asia. Research on the high-altitude mountainous regions of Asia with relatively short meteorological and hydrological records relies on paleoclimate proxy data with long time scales. The stable isotopes of tree-rings are insightful agents that provide information on pre-instrumental climatic and hydrological fluctuations, yet the variability of these data from different regions along the Tianshan Mountains has not been fully explored. Herein, we related climate data with tree-ring width (TRW) chronologies and δ13C (stable carbon isotope discrimination) series to discern if the Picea schrenkiana in the Ili and Manas River Basins are sensitive to climatic factors and baseflow (BF). The results show significant correlations between temperature and TRW chronologies, temperature and δ13C, relative humidity and TRW chronologies, and BF and δ13C. Temperature, particularly the mean late summer to early winter temperature, is a pronounced limiting factor for the tree-ring and the δ13C series in the Manas River Basin, located in the middle of the North Tianshan Mountains. Meanwhile, mean early spring to early autumn temperature is a limiting factor for that of the Ili River Basin, located on the southern slope of the North Tianshan Mountains. We conclude that different seasonal variations in temperature and precipitation of the two river basins exerted significant control on tree growth dynamics. Tree-ring width and tree-ring δ13C differ in their sensitivity to climate and hydrological parameters to which tree-ring δ13C is more sensitive. δ13C showed significant lag with precipitation, and the lag correlation showed that BF, temperature, and precipitation were the most affected factors that are often associated with source water environments. δ13C series correlated positively to winter precipitation, suggesting baseflow was controlling the length of the growing season. The tree-ring δ13C provided information that coincided with TRW chronologies, and supplied some indications that were different from TRW chronologies. The carbon stable isotopes of tree-rings have proven to be powerful evidence of climatic signals and source water variations.

The juniper tree forest is a critical component of the carbon, water, and energy cycles of Tajikistan. However, to date, long-term information about tree-ring isotopes is limited in this region. Here, we developed tree-ring width (TRW) and tree-ring 13C chronologies for juniper trees (Juniperus seravschanica (Juniperus excelsa subsp.polycarpos (K. Koch) Takht.) and Juniperus turkestanica (Juniperus pseudosabina Fisch. & C. A. Mey)) and investigated their dendroclimatic signals in the northwest of the Pamir-Alay (NWPA) mountains in Tajikistan. Tree-ring ∆13C and TRW of juniper presented different sensitivities to monthly precipitation. Moreover, ∆13C in juniper showed consistently significant relationships with climatic factors in larger seasonal windows than TRW did. Dendroclimatological analysis demonstrates that precipitation has significant effects on tree growth and isotope enrichment. Late summer to early winter temperature is one limiting factor for the TRW chronologies, but previous spring, summer, and autumn temperature and precipitation from the previous July to the current May were the dominant climatic factors accounting for inter-annual variations in the ∆13C chronologies. This verified that the multi tree-ring parameters of juniper in Tajikistan are a promising tool for investigating inter-annual climate variations. Furthermore, the stable carbon isotopes of tree rings have proven to be powerful evidence of climatic signals. The moisture-sensitive tree-ring isotope provides opportunities for complex investigations of changes in atmospheric circulation patterns and timing of seasonal rainfall. Our results highlight the need for more detailed studies of tree growth responses to changing climate and tree-ring isotopes to understand source water variations (especially baseflow) of the juniper tree forest.

The Taklimakan Desert is a typical arid area. Due to the needs of production and life, a total of 2 km2 of constructed green land (hereinafter referred to as CGL) has been formed in the sand dune, resulting in the uniform underlying surface of the desert having been changed, which has led to the change in the near-surface energy distribution pattern and the formation of a local climate of the CGL that is obviously different from that of the desert climate. Therefore, it is necessary to study the varied interval of the threshold of meteorological factors and the regional climate characteristics of the CGL under the background of desert. The main results are as follows. Firstly, from sunrise to noon, the increasing rate of temperature in natural sandy land (hereafter, NSL) was higher than that in CGL, and the opposite results occurred between noon and sunset. The peak temperature of CGL was 2 h later than that of NSL. At night, the temperature at the boundary of the CGL was generally higher than that of the NSL and the central area of the CGL. In addition, the results show that under the combined influence of underlying conditions, local circulation and small terrain, the CGL (middle) daily range of temperature > NSL (west) > CGL (east) > CGL (west). The positive temperature change period of CGL was significantly shorter than that of NSL in all seasons. However, temperature inversion occurred at night in all seasons. The intensity of the temperature inversion was strongest in winter, with a maximum temperature difference of 12.8 °C, followed by autumn, spring, and summer, with a maximum difference of 6.4 °C. Secondly, the wind speed in the daytime was higher than that at night, and the wind speed in NSL was higher than that in CGL. In summer, if the average wind speed of the NSL was quantified as 1.0 m/s, the wind speed lapse rate reached 30% at the boundary of the CGL. Similarly, in the central area of CGL, the wind speed lapse rate reached 71%.