We aim to investigate variations in the resorption efficiencies of 10 mineral nutrients [i.e. nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), zinc (Zn), aluminum (Al), iron (Fe) and copper (Cu)] in leaves of desert shrubs and to explore effects of aridity on resorption efficiency of these nutrients. Plant samples were collected from 10 sites in northern Xinjiang Uygur Autonomous Region of China. Samples of green and senesced leaves were analysed to determine concentrations of N, P, K, Mg, Ca, Mn, Zn, Al, Fe and Cu and thus the nutrient resorption efficiency. The mean nutrient concentrations in the desert shrubs varied, with the stoichiometric ratio Ca:N (19.3 mg g⁻¹):K (10.5 mg g⁻¹):Mg:P (1.01 mg g⁻¹):Al:Fe:Mn:Zn:Cu (4.78 mg kg⁻¹) = 4038:2950:2199:1816:211:37:32:11:2:1 in green leaves; and Ca:N (12.6 mg g⁻¹):Mg:K (7.6 mg g⁻¹):P (0.56 mg g⁻¹):Fe:Al:Mn:Zn:Cu (2.85 mg kg⁻¹) = 5583:3710:2943:2523:178:133:119:19:3.7:1 in senesced leaves. Resorption generally occurred for six elements (N, P, K, Cu, Mg and Mn, with average resorption efficiency 47.8%, 52.0%, 38.6%, 41.0%, 12.7% and 7.89%, respectively) during leaf senescence, while the other four nutrients tended to accumulate in senesced leaves, showing averagely negative resorption efficiencies [Ca (–3.87%), Al (−57.1%), Zn (−62.6%), Fe (−89.6%)]. Aridity showed strikingly different effects on the resorption process of the 10 nutrients. Of the four elements with totally (N/P/K) or mostly (Cu) positive observations of resorption efficiency, their resorption generally decreased with aridity, suggesting that drought stress had negative effects on the resorption efficiencies of these elements. In contrast, with at least one-third observations of resorption efficiency being negative, the other elements (Mg/Mn/Ca/Zn/Al/Fe) showed generally increasing resorptive tendency with aridity, except for Zn. This research provided a systematic analysis on the large variation and contrasting responses of the resorption of multi-elements to aridity in typical desert shrubs. Our findings foster the understanding of nutrient resorption patterns of desert plants and enable us to better predict the contrastive effects of drought stress on the cycling of diverse nutrients and the consequent stoichiometric decoupling in plants of desert ecosystems.

This study recommends a non-grinding measurement method of leaf pH which can reduce the destructive interference to the measured fresh-leaf pH values. To verify the accuracy of this method, we measured leaf pH with the non-grinding and grinding method and further assessed the dilution effect on leaf pH in the grinding process. Compared with the non-grinding method, the grinding method significantly increased the measured pH value; leaf pH increased with decreasing leaf–water ratio in the procedure of the grinding method, but gradually stabilized. The grinding effects of severe physical damage and thereafter oxidization of leaf samples, and the dilution effects according to the Debye–Hückel limiting law and acid-base ionization theory, may both contribute to the increased leaf pH measured with the grinding method. Thus, leaf pH measured with the non-grinding method was expected to be much closer to those of leaf sap in vivo and be more suitable to indicating the dynamic variation or instant response of leaf pH to the environmental changes. Finally, considering that non-significant difference had been proved in the measured leaf pH between dried, frozen, refrigerated, and fresh ground samples, a conversion equation was provided to facilitate mutual conversion of the results with non-grinding fresh samples (y) against those with grinding dried samples (as representative) (x): y = 1.097x − 0.722.

The dynamic fluctuations in the soil organic carbon (SOC) stock, a fundamental part of the terrestrial ecosystem’s carbon stock, are critical to preserving the global carbon balance. Oases in arid areas serve as critical interfaces between oasis ecosystems and deserts, with land use changes within these oases being key factors affecting soil organic carbon turnover. However, the response of the soil SOC-CO₂-SIC (soil inorganic carbon) micro-carbon cycle to oasis processes and their underlying mechanisms remains unclear. Five land-use types in the Alar reclamation area—cotton field (CF), orchard (OR), forest land (FL), waste land (WL), and sandy land (SL)—were chosen as this study’s research subjects. Using stable carbon isotope technology, the transformation process of SOC in the varieties of land-use types from 0 to 100 cm was quantitatively analyzed. The results showed the following: (1) The SOC of diverse land-use types decreased with the increase in soil depth. There were also significant differences in SIC-δ¹³C values among the different land-use types. The PC(%) (0.73 g kg⁻¹) of waste land was greatly higher than that of other land-use types (p < 0.05) (factor analysis of variance). (2) The CO₂ fixation in cotton fields, orchards, forest lands, and waste land primarily originates from soil respiration, whereas, in sandy lands, it predominantly derives from atmospheric sources. (3) The redundancy analysis (RDA) results display that the primary influencing factors in the transfer of SOC to SIC are soil water content, pH, and microbial biomass carbon. Our research demonstrates that changes in land use patterns, as influenced by oasis processes, exert a significant impact on the conversion from SOC to SIC. This finding holds substantial significance for ecological land use management practices and carbon sequestration predictions in arid regions, particularly in the context of climate change.

Desert halophytes are a special plant group widely distributed in desert ecosystems. Studying their ecological stoichiometric characteristics is helpful for understanding their nutrient utilization characteristics and survival strategies. In this study, three functional groups of halophyte shrubs (euhalophytes, pseudohalophytes, and secretohalophytes) were studied in the Xinjiang desert, and the ecological stoichiometric characteristics of their leaves and their relationships with soil factors were evaluated. The results showed that the C content in secretohalophytes (442.27 ± 3.08 mg g⁻¹) was significantly higher than that in the other functional groups (p < 0.05). The N and P contents in euhalophytes (22.17 ± 0.49 mg g⁻¹ and 1.35 ± 0.04 mg g⁻¹, respectively) were significantly higher than those in halophytes (p < 0.05). The N/P results showed that the growth rates of euhalophytes and pseudohalophytes were more susceptible to P limitation, whereas that of secretohalophytes was more susceptible to both N and P limitations, indicating that there were differences in nutrient characteristics among different functional groups. The results of the redundancy analysis showed that the leaf C, N, and P contents of euhalophytes were most affected by electrical conductivity (EC), whereas those of pseudohalophytes and secretohalophytes were most affected by the soil C content, indicating that different functional groups of halophyte shrubs had different responses to soil factors. The results of this study revealed the nutrient utilization characteristics of different functional groups of halophyte shrubs in the Xinjiang desert and their response and adaptation mechanisms to soil factors, thereby providing a basis for desert ecosystem management.

In the past 30 years, Northwest China has experienced a warm and humid climate increase trend. How this climate change will affect the species diversity of plant communities is a hot issue in ecological research. In this study, four α diversity indexes were applied in 29 shrub communities at desert sites in Xinjiang, including the Margalef index, Simpson index, Shannon–Wiener index, and Pielou index, to explore the relationship between the α diversity of the desert shrub communities and climate factors (mean annual temperature (MAT) and mean annual precipitation (MAP)). The species diversity indexes varied across these different desert shrub communities. Tamarix ramosissima communities had the highest Margalef index, while the Krascheninnikovia ewersmannia communities had the lowest Margalef index; T. ramosissima communities also showed the highest Simpson index and Shannon–Wiener index, but Alhagi sparsifolia communities showed the lowest Simpson index and Shannon–Wiener index. The Ephedra przewalskii communities and Karelinia caspica communities showed the highest and the lowest Pielou index, respectively. The α diversity indexes (except the Pielou index) of desert shrub communities had a significantly positive correlation with MAP (p < 0.05) but a non-significantly correlation with MAT (p > 0.05). These results indicate that, compared with temperature, water conditions are still a more vital climatic factor affecting the species diversity of desert shrub communities in Xinjiang, and thus, the recent “warm and humid” climate trend in Xinjiang affects the α diversity of desert shrub communities.