Aridity and salinity have a key role in driving physiological and ecological processes in desert ecosystems. However, how community‐scale foliar nutrients respond to aridity and salinity, and how these responses might vary with community composition along aridity and salinity gradients is unclear. We hypothesize that the response will be a shift in community stoichiometric values resulting from nutrient variability of shared species and unique species (site‐specific species), but little research has addressed the relative contribution of either component. We analyzed the community‐scale stoichiometric response of a desert community of perennial plants along an aridity and salinity transect by focusing on foliar nitrogen (N) and phosphorous (P) concentrations and N:P ratios. After evaluating the shared and unique species variability, we determined their relative contribution to the community stoichiometric response to aridity and salinity, reflected by changes in nonweighted and weighted community‐average values. Community‐scale stoichiometry decreased significantly under aridity and salinity, with significantly consistent changes in nonweighted and weighted community‐average stoichiometry for most shared and unique species measurements. The relative contribution of unique species shifts to the changes in community stoichiometry was greater (15%–77%) than the relative contribution of shared species shifts (7%–45%), excluding the change in weighted P concentration under aridity. Thus, the shifts of unique species amplified the community stoichiometric response to environmental changes. Synthesis. These results highlighted the need for a more in‐depth consideration of shared and unique species variability to understand and predict the effects of environmental change on the stoichiometry of plant communities. Although variation in community stoichiometry can be expected under extreme aridity and salinity conditions, changes of unique species could be a more important driver of the stoichiometric response of plant communities.

Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011 a field experiment combined two methods (static closed chambers and a closed dynamic soil CO₂ flux system) in alpine grasslands located in the Tianshan Mountains. We examined the effects of grazing regime on ecosystem respiration (R_e) both outside (NGS) and during (GS) the growing season and determined the pattern of R_e in relation to climate change. There was no significant change in CO₂ emissions under grazing. Heterotrophic respiration (R_h) accounted for 78.5% of R_e with short-term grazing exclusion and 93.2% of R_e with long-term grazing exclusion. R_e, R_h and autotrophic respiration (R_a) fluxes outside the growing season were equivalent to 12.9%, 14.1% and 11.4% of the respective CO₂ fluxes during the growing season. In addition, our results indicate that soil water content played a critical role in R_a in the cold and arid environment. Both R_h and R_e were sensitive to soil temperature. Moreover, our results suggest that grazing exerted no significant effect on CO₂ emissions in these alpine grasslands.

The semiparasitic weed Pedicularis kansuensis Maxim. has rapidly spread in the alpine grasslands of northern China over the past twenty years and has caused serious ecological problems. In order to effectively halt the spread of this weed, a thorough understanding of the dormancy type and the seed-germination ecology of P. kansuensis is required. We have conducted a series of experiments to investigate the effects of plant growth regulators (gibberellin (GA₃) and strigolactone synthesis (GR24)), as well as different abiotic (temperature, light, cold stratification, and drought) and biotic (aqueous extracts of three native dominant plants) factors on the seed-germination characteristics of P. kansuensis. The seed-germination percentages ranged from 2% to 62% at all of the temperatures that were examined, with the highest occurring at 25/10 °C. The light conditions did not significantly affect the germination percentage. The seed germination was greatly improved after two to eight weeks of cold stratification. The seed germination decreased dramatically with an increasing polyethylene glycol (PEG-6000) concentration, from 55% to 0%, under 10% and 20% PEG-6000. The seed germination was improved at a proper concentration of GA₃, GR24, and the aqueous extracts of Festuca ovina L., Stipa purpurea L., and Leymus secalinus (Georgi) Tzvel. Furthermore, in the pot experiment, the seedling emergence of P. kansuensis was also improved by the cultivation of these three dominant grasses. These findings indicate that the dormancy type of P. kansuensis seeds is non-deep physiological dormancy, and such findings will help in paving the way for the creation of effective weed management strategies, based on a thorough knowledge of germination ecology.

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.

Aboveground biomass (AGB) is a sensitive indicator of grassland resource quality and ecological degradation. However, accurately estimating AGB at large scales to reveal long-term trends remains challenging. Here, single-factor parametric models, multi-factor parametric models, and multi-factor non-parametric models (Random Forest) were developed for three grassland types (alpine meadow, alpine grassland, and swampy meadow) in the Bayanbuluk Grassland using MODIS satellite data and environmental factors, including climate and topography. A 10-fold cross-validation method was employed to assess the accuracy and stability of these models, and an AGB remote sensing inversion model was established to estimate the AGB of the Bayanbuluk Grassland from 2005 to 2024. Moreover, the BEAST mutation test, Theil–Sen median trend analysis, and Mann–Kendall test were used to analyse the temporal trends of AGB, identify the years of mutation points, and explore the changes in AGB across the entire study period (2005–2024) and at 5-year intervals, considering the influence of climatic factors. The results indicated that the machine learning (RF) model outperformed both multi-factor parametric and single-factor parametric models, with specific improvements in R² and RMSE across all grassland types. For instance, the RF model achieved an R² of 0.802 in alpine grasslands, outperforming the multi-factor parametric model with an R² of 0.531. The overall spatial distribution of AGB exhibited heterogeneity, with a gradual increase from northwest to southeast over the study period. Interannual AGB changes fluctuated significantly, with an overall increasing trend. Notably, from 2015 to 2019, 78% of the Bayanbuluk Grassland area showed a nonsignificant increase in AGB. Specifically, 46.7% of the alpine meadow AGB, 23% of the alpine grassland AGB, and 8.3% of the swampy meadow AGB showed non-significant increases. Further, temperature was found to be the dominant driver of AGB, with a stronger effect on alpine meadows and alpine grasslands than on swampy meadows. This is likely due to the relatively constant moisture levels in the swampy meadows, where precipitation plays a more prominent role. This study provides a comprehensive assessment of AGB trends, including both spatial and temporal analyses, which will inform future grassland resource management.