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Actual evapotranspiration (ETa) is an essential component of Earth's global energy balance and water cycle. The Paris Agreement aspires to limit global mean surface warming to2 °C and no1.5 °C relative to preindustrial levels. However, it is uncertain how this global level will impact the shifts in the extents of sandy areas caused by global desertification. Using Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) datasets and advection-aridity models, we investigated the spatiotemporal features of ETa in sandy areas in northern China under global warming scenarios of 1.5 °C and 2.0 °C. The four climate models indicated significant increases in ETa in arid areas across northwestern China. Over time, the ETa value under only the representative concentration pathway 2.6 (RCP2.6) emission scenario increased towards a plateau and significantly increased in the other three emission scenarios (P 0.01) under global warming of 1.5 °C and 2.0 °C. In terms of the spatial variations, ETa showed an increasing trend in all seasons except winter. The maximum ETa was 84.61 mm, and high values were mainly located in the southeast of the study area. Precipitation and the normalized difference vegetation index (NDVI) showed good correlations with ETa in the sandy areas in northern China. The sandy areas in northern China showed decreasing trends (0.45 km

Accurate predictions of water vapor at large temporal and spatial scales are particularly important in global studies. In recent years, Central Asian grasslands have been subject to both intensive grazing and variability in climatic conditions. However, uncertainties about grazing on water cycling under climate change still exist. Therefore, the Biome-BGC grazing model was applied to assess the effects of grazing on evapotranspiration (ET) and water use efficiency (WUE). Three grassland types were studied during the period 1979–2011: forest meadow (FM), temperate grassland (TG) and desert grassland (DG). ET shows a gradual decreasing trend from FM (365.65 ± 36.86 mm m−2 yr−1) to DG (183.32 ± 21.15 mm m−2 yr−1), and WUE ranging from 0.62 ± 0.03 g C kg-1 H2O in FM to 1.12 ± 0.10 g C kg−1 H2O in TG, with an average of 0.83 ± 0.05 g C kg−1 H2O. Although there was a significant decrease in ET of 1.47–2.72 mm m−2 yr−1, WUE increased at a rate of 0.004 g C kg−1 H2O yr−1 in Central Asia. From 1979 to 2011, grazing lowered ET by 7.47% in Central Asia; the reduction rates for FM, TG and DG were 3.10%, 12.70% and 7.42%, respectively. In general, grazing decreased WUE by 3.60%. From non-grazed to grazed scenario, WUE increased by 6.86% for FM, but WUE decreased by 7.27% and 5.61% for TG and DG. An over-compensation of GPP under grazing might account for the higher WUE under certain grazing intensities. In order to achieve maximum utilization of water efficiency, proper grazing intensity for TG, DG and FM should be limited to 0.17, 0.39 and 0.38 head/ha, respectively.

Plastic film has been widely applied to address water shortages by reducing soil evaporation in arid and semi-arid regions, but it simultaneously affects soil nitrous oxide (N2O) emissions. Moreover, after the application of plastic film, the ability of nitrification inhibitor to reduce N2O emissions remains unclear. In this study, the chamber method was used to measure N2O emissions and a modified diffusion equilibrium sampler was used to obtain N2O concentrations in an oasis cotton field. Non-mulched and mulched treatments were used to investigate the influence of plastic mulching on soil N2O dynamics, and mulched plus nitrapyrin treatment was used to evaluate the ability of nitrapyrin to reduce N2O emissions under plastic mulching. Moreover, we also estimated the net economic return and cost related to an eventual environmental taxation on N2O emission of these practices. In all treatments, the ridge soil was the origin of most N2O (82–87%) emissions, which remained at low levels during the non-fertigation period (ranging from 0.4–17.1 g N ha−1 day−1) and sharply increased after the split application of urea; emissions during the fertigation periods accounted for 57–85% of the total N2O emissions in all treatments. Compared with the non-mulched treatment, the use of plastic film is a “win-win” strategy for both agricultural income (net economic returns increased by $436–522 ha−1 year−1) and N2O mitigation (emissions reduced by 19–28%), even without incentives. Although the addition of nitrapyrin to the urea reduced the cumulative N2O emissions by 23–39% under plastic mulching, and therefore reduced the costs related to an eventual environmental taxation on N2O emission by approximately $2 ha−1 year−1, this benefit could not compensate for the additional cost of inputting nitrapyrin ($24 ha−1 year−1) because this technique did not have a significant effect on cotton yields. Therefore, the use of nitrapyrin is probably a “lose-win” strategy for farmers and N2O mitigation and not suitable for reducing N2O emissions in oasis cotton fields.

The application of plastic film to agricultural fields has been widely used in the arid and semi-arid regions of China to improve crop productivity and soil organic carbon storage. However, the impact of this practice on soil respiration under future climate scenarios remains poorly understood. Process-based model is a useful tool for simulating the effect of this practice on soil biochemical processes and for predicting future changes in soil respiration under different climate scenarios. In this study, the denitrification-decomposition (DNDC) model was evaluated against measured soil respiration. The DNDC model was used to simulate the temporal variation of soil respiration, and the application of plastic film increased the cumulative carbon dioxide (CO2) emissions compared with that of the fields without plastic film. Sensitivity tests indicated that plastic mulching decreased the sensitivity of DNDC-simulated soil respiration and plant biomass to changes in the temperature, precipitation and CO2 concentration. Across different climate scenarios, the DNDC model predicted that both soil respiration and plant biomass in the mulched treatment slightly changed from −0.2% to 2.1% and from −0.7% to 1.2%, respectively; and in the non-mulched treatment, soil respiration and biomass changed from −4.7% to 10.9% and from −8.7% to 7.8%, respectively. In the arid agricultural region of China, if the pollution of residual mulch film in the fields can be effectively controlled, the application of plastic film is an efficient method for increasing crop productivity and would likely mitigate changes in soil respiration under future climate scenarios.

Water is the most important factor limiting the growth of sand-binding vegetation (SBV) in desert ecosystems. This study explored the water sources and water use strategies of SBV under a natural precipitation gradient. Six typical SBV species were selected, comprising three tree species, Pinus sylvestris, Haloxylon ammodendron and Populus euphratica, and three shrub species, Artemesia ordosica, Caragana korshinshii and Tmarix ramosissima. The stable isotope values (δD, δ18O) of xylem water and potential water sources (precipitation, soil water, and groundwater) of these species under a precipitation gradient in the sandy regions of northern China were measured. In addition, the relative contributions of the different potential water sources to water use by SBV were analyzed using the MixSIAR model. The results indicated that the Local Meteoric Water Lines (LMWLs) of the six SBV species were located on the right side of the Global Meteoric Water Line (GMWL), with the degree of deviation gradually increasing with a decrease in precipitation. The results showed that T. ramosissima, H. ammodendron and P. euphratica mainly used groundwater (GW), whereas P. sylvestris, A. ordosica and C. korshinshii mainly used soil water. Among those species using soil water, P. sylvestris and A. ordosica mainly used shallow soil water (20–80 cm). P. sylvestris and C. korshinshii showed the highest soil water utilization rate of 14%, whereas P. euphratica showed the lowest soil water utilization rate of 2%. The different SBV species showed significantly different soil water utilization rates due to the influence of plant root distribution (p

Central Asia (CA) is a core area of global desertification, but the effect of the intensifying "global greening" policy on the desertification process under global warming scenarios in CA remains unclear. Based on multi-source remote sensing data and Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) 2b climate data, this study investigated desertification in CA using actual evapotranspiration (ETa), temperature and precipitation as driving factors. Coupling with the CA-Markov model, the inversion method of desertification was improved, and the evolution normal form of desertification in CA was proposed. Finally, spatio-temporal variations of desertification in CA were quantified. The results indicate that temperature, precipitation, and normalized difference vegetation index (NDVI) in CA increased during the historical period (1980-2015), with sudden changes in 1994. In contrast, although ETa exhibited fluctuating increases (7.41 mm/10 yr) during this period, no sudden changes were observed in 1994. In the future (2006-2099), the climate of CA will become warmer and wetter. With reference to 1980-2005, precipitation under global warming of 2.0 °C (GW2.0) will be higher than that under global warming of 1.5 °C (GW1.5) by 10.3 mm, and ETa will increase by 20.88 mm and 27.54 mm under GW1.5 and GW2.0, respectively. Although the area of desert lands has decreased (5.94 × 104 km2/10 yr), the area of potential desert lands has increased (0.17 × 104 km2/10 yr). With global warming, this situation will continue to intensify, mainly in Xinjiang of China, and Kazakhstan. The Aral Sea plays an important role in the desertification of CA. The potential increase in desert land under GW2.0 is equivalent to the current water area of the Aral Sea. The findings could provide policy support for combating desertification in CA and promoting the achievement of the Sustainable Development Goals.

In several studies of agricultural ecosystems, researchers have focused on the soil-surface carbon dioxide (CO2) effluxes, but the nature of CO2 production in the soil profile and its influencing factors remain unclear. In this study, the soil-surface CO2 effluxes in an oasis cotton field were measured using the chamber method, and the CO2 concentrations were used to estimate the CO2 production in different layers of the soil profile using the gradient method. The soil CO2 concentrations increased with increasing soil depth, whereas CO2 production decreased with increasing soil depth. Both soil-surface CO2 effluxes and CO2 production in the 0–40 cm layers exponentially increased with increasing temperature. Irrigation temporarily reduced the soil-surface CO2 effluxes by 19–63% through inhibiting CO2 production in the 10–40 cm layer but did not affect the CO2 production in the 0–10 cm layer. CO2 production mainly occurred in the 0–10 cm layer, and this cumulative production accounted for 63–67% of the total production throughout the soil profile (0–40 cm). The application of nitrogen (N) fertilizer enhanced the rate of CO2 production in the 0–20 cm layer by increasing the root biomass and soil mineral N content. A positive correlation was detected between the soil-surface CO2 efflux and soil NO3− content in 2015, but no significant correlations were found between the soil-surface CO2 efflux and soil NH4+ contents in any treatment. A higher soil-surface CO2 efflux was observed under high soil temperature and a certain soil moisture range (0.21–0.23 cm3 cm− 3). An analysis of the soil profile revealed higher CO2 production rates detected in the 0–10 cm layer under high soil temperature and moisture conditions, but higher rates were observed under high soil temperature and low soil moisture conditions in the 10–20 cm layer. Therefore, our results suggest that the effects of fertilization, soil temperature and moisture on CO2 production vary depending on the soil depth. These findings might improve our understanding of the mechanisms underlying soil respiration in soil profiles.

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

The denitrification-decomposition (DNDC) model is a useful tool for integrating the effects of agricultural practices and climate change on soil nitrous oxide (N2O) emissions from agricultural ecosystems. In this study, the DNDC model was evaluated against observations and used to simulate the effect of plastic mulching on soil N2O emissions and crop growth. The DNDC model performed well in simulating temporal variations in N2O emissions and plant growth during the observation period, although it slightly underestimated the cumulative N2O emissions, and was able to simulate the effects of plastic mulching on N2O emissions and crop yield. Both the observations and simulations demonstrated that the application of plastic film increased cumulative N2O emissions and cotton lint yield compared with the non-mulched treatment. The sensitivity test showed that the N2O emissions and lint yield were sensitive to changes in climate and management practices, and the application of plastic film made the N2O emissions and lint yield less sensitive to changes in temperature and irrigation. Although the simulations showed that the beneficial impacts of plastic mulching on N2O emissions were not gained under high fertilizer and irrigation scenarios, our simulations suggest that the application of plastic film effectively reduced soil N2O emissions while promoting yields under suitable fertilizer rates and irrigation. Compared with the baseline scenario, future climate change significantly increased N2O emissions by 15–17% without significantly influencing the lint yields in the non-mulched treatment; in the mulched treatment, climate change significantly promoted the lint yield by 5–6% and significantly reduced N2O emissions by 14% in the RCP4.5 and RCP8.5 scenarios. Overall, our results demonstrate that the application of plastic film is an efficient way to address increased N2O emissions and simultaneously enhance crop yield in the future.

Ecological restoration of degraded riparian Tugai forests is a key driver to combat desertification in arid regions. Previous studies have focused mainly on changes in groundwater as the underlying mechanisms of Tugai forest’s decline. We evaluated species composition and diversity of Tugai forest and their relationship to groundwater, soil salinity, and soil nutrient. Using 73 quadrats (100 m × 100 m) from 13 transects located perpendicularly to river in the upper reaches of the Tarim River. Eighteen plant species belonging to sixteen genera and eight families were recorded, and the dominant species included Populus euphratica, Phragmites communis, and Tamarix ramosissima. Three P. euphratica stand ages were detected: young stand, mature stand, and old stand. There were significant differences in species diversity, groundwater depth, groundwater salinity, distance from the quadrat to the river channel, soil moisture content, pH, electrical conductivity, total salt, Cl−, SO42−, Ca2−, Mg2+, Na+, K+, soil organic carbon, and soil organic matter across the stand ages. Seven species were identified as indicators of the three stand ages. Redundancy analysis indicated that the Tugai forest diversity indices were negatively correlated with groundwater depth, groundwater salinity, and distance from the river, and positively associated with electrical conductivity, total salt, pH, Cl−, SO42−, CO32−, soil organic matter, soil organic carbon, and soil moisture content. Plant diversity was the highest at 3–6 m groundwater depth, followed by 0–3 m and then 6–9 m, with the lowest recorded at > 9 m. The appropriate groundwater depth for herbs was about 1–4 m, whereas the depth for trees and shrubs was about 3–6 m. The groundwater depth < 6 m was deemed suitable for the growth of desert riparian forests. This results provide a scientific reference for the ecological restoration and protection for Tugai forests in arid areas.

Riparian plant diversity in arid regions is sensitive to changes in groundwater. Although it is well known that groundwater has a significant influence on plant diversity, there have been few studies on how groundwater and soil salinity impact plant community in desert riparian ecosystems. Therefore, we surveyed 77 quadrats (100 m × 100 m) to examine the relationship between groundwater depth, groundwater salinity, soil salinity and plant community in the upper reaches of the Tarim River. Data were analyzed with two-way indicator species analysis (TWINSPAN), detrended canonical correspondence analysis (DCCA) and principal component analysis (PCA). The results indicated that Populus euphratica, Tamarix ramosissima, and Phragmites australis were the dominant plants among trees, shrubs and herbs, respectively. Five plant community types were classified. There were significant differences in species diversity, soil moisture, soil salinity, groundwater depth and groundwater salinity across the community types. The composition and distribution of plant community are significantly influenced by groundwater depth, groundwater salinity, soil moisture, distances from the river to the quadrats, soil pH, electrical conductivity, total salt, CO32−, Cl−, SO42−, Ca2+, Mg2+, Na+ and K+. Shallow groundwater depth, low groundwater salinity, and high soil moisture and soil salinity were associated with higher plant diversity.

In recent years, the climate in the arid region of Northwest China has become warmer and wetter, however, glaciers in the north slope of the West Kunlun Mountains (NSWKM) show no obvious recession, and river flow is decreasing or stable. This contrasts with the prevalent response of glaciers to climate change, which is recession and initial increase in glacier discharge followed by decline as retreat continues. We comparatively analyzed multi-timescale variation in temperature&ndash, precipitation&ndash, snow cover-runoff in the Yarkant River Basin (YRK), Karakax River Basin (KRK), Yurungkax River Basin (YUK), and Keriya River Basin (KRY) in the NSWKM. The Mann&ndash, Kendall trend and the mutation&ndash, detection method were applied to data obtained from an observation station over the last 60 years (1957&ndash, 2017) and MODIS snow data (2001&ndash, 2016). NSWKM temperature and precipitation have continued to increase for nearly 60 years at a mean rate of 0.26 &deg, C/decade and 5.50 mm/decade, respectively, with the most obvious trend (R2 &gt, 0.82) attributed to the KRK and YUK. Regarding changes in the average snow-cover fraction (SCF): YUK (SCF = 44.14%) &gt, YRK (SCF = 38.73%) &gt, KRY (SCF = 33.42%) &gt, KRK (SCF = 33.40%). Between them, the YRK and YUK had decreasing SCA values (slope &lt, &minus, 15.39), while the KRK and KRY had increasing SCA values (slope &gt, 1.87). In seasonal variation, the SCF of the three of the basins reaches the maximum value in spring, with the most significant performance in YUK (SCF = 26.4%), except for YRK where SCF in spring was lower than that in winter (&minus, 2.6%). The runoff depth of all river basins presented an increasing trend, with the greatest value appearing in the YRK (5.78 mm/decade), and the least value in the YUK (1.58 mm/decade). With the runoff response to climate change, temperature was the main influencing factor of annual and monthly (summer) runoff variations in the YRK, which is consistent with the runoff-generation rule of rivers in arid areas, which mainly rely on ice and snow melt for water supply. However, this rule was not consistent for the YUK and KRK, as it was disturbed by other factors (e.g., slope and slope direction) during runoff generation, resulting in disruptions of their relationship with runoff. This research promotes the study of the response of cold and arid alpine regions to global change and thus better serve regional water resources management.

Drought, one of the most common natural disasters that have the greatest impact on human social life, has been extremely challenging to accurately assess and predict. With global warming, it has become more important to make accurate drought predictions and assessments. In this study, based on climate model data provided by the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP), we used the Palmer Drought Severity Index (PDSI) to analyze and project drought characteristics and their trends under two global warming scenarios&mdash, 1.5 &deg, C and 2.0 &deg, C&mdash, in Central Asia. The results showed a marked decline in the PDSI in Central Asia under the influence of global warming, indicating that the drought situation in Central Asia would further worsen under both warming scenarios. Under the 1.5 &deg, C warming scenario, the PDSI in Central Asia decreased first and then increased, and the change time was around 2080, while the PDSI values showed a continuous decline after 2025 in the 2.0 &deg, C warming scenario. Under the two warming scenarios, the spatial characteristics of dry and wet areas in Central Asia are projected to change significantly in the future. In the 1.5 &deg, C warming scenario, the frequency of drought and the proportion of arid areas in Central Asia were significantly higher than those under the 2.0 &deg, C warming scenario. Using the Thornthwaite (TH) formula to calculate the PDSI produced an overestimation of drought, and the Penman&ndash, Monteith (PM) formula is therefore recommended to calculate the index.

Soil salt accumulation and salt leaching are very important issues for a long-term irrigation-dominated oasis with shallow groundwater in arid land. The critical ratio of drainage to irrigation (CRDI) was defined and determined to help the guide drainage and irrigation practices and maintain sustainable oasis agricultural development. This study aimed to identify the soil salinity evolution under long-term irrigation and to determine the threshold of irrigation to drainage with land-use change and groundwater depth by regression, water and salt balance, and geostatistical analysis. The results showed that the soil salinity in 0–20 cm soil depth has decreased greatly in the Weigan Oasis over the past 60 years, with an annual average decrease of 0.68 g·kg−1 in the Weigan Oasis. The soil salt content generally increases from inside to outside of the region and varies from the upperstream to downstream. In the past 30 years, land-use change has caused a sharp reduction in the salinity in the region, and the process of irrigation and drainage has made a decrease in the total salt of the irrigated district of 207.38 × 105 t. Meanwhile, shallow groundwater depth and salinity are the main factors influencing soil salinization in this fluvial oasis. A CRDI is determined to be 8.20% in the Weigan Oasis. In conclusion, our study provides scientific support for the prevention and control of regional soil salinization, as well as a managerial basis for the rational allocation of water resources in long-term irrigation-dominated oasis.

Climate warming has widely variable effects on terrestrial ecosystems, and warming-induced changes in soil erosion could accelerate or slow down future warming. Numerous methods and models have been developed to evaluate soil erosion. However, the quantification of the impact of climate change on soil erosion and selection of the most appropriate soil erosion model for a particular study area remain unclear. With the intensification of climate warming, solutions to these problems are becoming increasingly more important. In this study, we performed a meta-analysis of research on global soil erosion to verify the effects of climate warming on soil erosion. Four databases were searched for relevant peer-reviewed publications from 1980 to 2019 using five keywords. The results showed that soil erosion has increased worldwide, mainly in semiarid areas (p

The simulation results of CMIP5 (Coupled Model Inter-comparison Project phase 5) multi-model ensemble in the Indus River Basin (IRB) are compared with the CRU (Climatic Research Unit) and APHRODITE (Asian Precipitation-Highly-Resolved Observational Data Integration Towards Evaluation) datasets. The systematic bias between simulations and observations is corrected by applying the equidistant Cumulative Distribution Functions matching method (EDCDFm) and high-resolution simulations are statistically downscaled. Then precipitation and temperature are projected for the IRB for the mid-21st century (2046–2065) and late 21st century (2081–2100). The results show that the CMIP5 ensemble captures the dominant features of annual and monthly mean temperature and precipitation in the IRB. Based on the downscaling results, it is projected that the annual mean temperature will increase over the entire basin, relative to the 1986–2005 reference period, with greatest changes in the Upper Indus Basin (UIB). Heat waves are more likely to occur. An increase in summer temperature is projected, particularly for regions of higher altitudes in the UIB. The persistent increase of summer temperature might accelerate the melting of glaciers, and has negative impact on the local freshwater availability. Projections under all RCP scenarios show an increase in monsoon precipitation, which will increase the possibility of flood disaster. A decreasing trend in winter and spring precipitation in the IRB is projected except for the RCP2.6 scenario which will cause a lower contribution of winter and spring precipitation to water resources in the mid and high altitude areas of the IRB.

Soil salinization largely affects greenhouse gas emissions from soils, but its effects on the temperature sensitivity (Q10) of soil carbon dioxide (CO2) emissions and nitrous oxide (N2O) emissions remain unclear. In this study, a temperature-controlled (15 °C and 25 °C) microcosm experiment was performed for 56 days to evaluate the effects of soil salinity (0.1%, 0.3%, 0.6% and 1.0% salt contents) on the Q10 of CO2 emissions, N2O emissions and phospholipid fatty acid (PLFA)-distinguishable microbial communities in sandy clay loam (SCL) soil and silty clay (SC) soil. In both soils, soil salinity inhibited soil microbial respiration under both temperature conditions. However, soil salinity significantly (p 0.05) difference in the Q10 of soil N2O emissions among the four salinity levels in the SCL soil, but soil salinization significantly (p

The ‘4 per mille’ initiative, launched in 2015, highlighted the crucial role of soil organic carbon (SOC) sequestration in food security and climate change adaptation and mitigation. The objectives of this study were to investigate the changes in the SOC stock (SOCs) with depth and time and explore the SOC accumulation process, in a millennium chronosequence derived from marine sediments. Chronofunctions were formulated based on SOCs at different depths to evaluate the effects of sampling depth on chronofunctions and the rates of SOC sequestration. The depth distribution of SOCs showed that SOC accumulation occurred mainly in the top 40 cm, with 69% of the SOC being distributed in the upper 0–40 cm layers. The chronofunctions yielding the best fits changed from linear to power and then to logarithmic, suggesting that sampling depth affected the chronofunction type. The SOCs for the entire profile (0–100 cm) could be estimated from that in the 0–20 cm or 0–50 cm, which can potentially aid the estimation of legacy SOC data. The SOC sequestration rates were found to be high at the beginning of development, gradually slowing down with time. The soil in this area can sequestrate SOC for more than 2000 years, at a rate greater than 0.4%. Spectroscopy and digital soil mapping methods can provide accurate and acceptable SOC data pertaining to agriculture and climate change and could be a potential technology for global SOC monitoring.

Remarkable warm‒wet climate shifts and intensive cropland expansion strongly affected carbon (C) cycle and threaten agricultural sustainability in northwest China. In this study, we integrated a process-based ecosystem model and an empirical C bookkeeping model to investigate the coupled and isolated effects of arable land conversions and climate change (CLM) on regional C balance in a typical watershed of northwest China. Results revealed that the farmland area increased by 3367.31 km2 during 1979–2014. The combined effects of CLM with net cropland expansion enlarged the vegetation C (VEGC) and the soil organic C (SOC) stock by 2.83 and 11.83 Tg, respectively, and were strongest in 2008–2014. The conversions between desert grassland and cropland were the major driving forces for regional C balance. Cropland expansion shared equal effects on VEGC increase with CLM, but its effect on SOC increment was 53 times larger than CLM’s. VEGC was more responsive to CLM, whereas SOC gained more benefits from land management. The C sink from reclamation suffered from high water consumption and is facing great threats due to glaciers and mountain lake shrinking and groundwater overpumping. Water-saving irrigation techniques and environmentally friendly water use strategies are essential for local agricultural sustainability.

Water use efficiency (WUE) is an important variable used in hydrometeorology study to reveal the links between carbon-water cycles in sandy ecosystems which are highly sensitive to climate change and can readily reflect the effects of it. In light of the Paris Agreement, it is essential to identify the regional impacts of 0.5 °C of additional global warming to inform climate adaptation and mitigation strategies. Using the modified Carnegie-Ames-Stanford Approach (CASA) and Advection-Aridity (AA) models with global warming values of 1.5 °C and 2.0 °C above preindustrial levels from Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b) datasets, we conducted a new set of climate simulations to assess the effects of climate on WUE (the ratio of net primary productivity (NPP) to actual evapotranspiration (ETa)) in different sandy land types (mobile sandy land, MSL; semimobile/semifixed sandy land, SMSF; and fixed sandy land, FSL) during the period of baseline (1986–2005) and future (2006–2100). The spatiotemporal patterns of ETa, NPP, and WUE mostly showed increasing trends; the value of WUE decreased (6.40%) only in MSL with an additional 0.5 °C of warming. Meteorological and vegetation factors determined the variations in WUE. With warming, only the correlation between precipitation and WUE decreased in the three sandy land types, and the leaf area index (LAI) increased with an additional 0.5 °C of warming. The desertification degree comprehensively reflects the linkages among the standardized precipitation evapotranspiration index (SPEI), LAI and WUE. Simulation results indicated the sandy area extent could potential increase by 20 × 104 km2 per decade on average during 2016–2047 and that the increase could be gradual (2.60 × 104 km2 per decade) after 2050 (2050–2100). These results highlight the benefits of limiting the global mean temperature change to 1.5 °C above preindustrial levels and can help identify the risk of desertification with an additional 0.5 °C of warming.