Accurate evapotranspiration (ET) estimation is vital for the ecology and water resource management of arid and semiarid regions. This study focused on the Kolqin Sandy Land Inland Closed Basin. The simulation of energy flux data for the area was conducted by applying Landsat 8 data from 2018 to 2022 during the growing season, the Two-Source Energy Balance (TSEB), and the Mapping Evapotranspiration at High Resolution with Internalized Calibration (METRIC) models. The validation of both models was performed via eddy covariance systems and large-aperture scintillometers, and the applicability of both models was compared. At the ecosystem scale, the TSEB model exhibited excellent accuracy of latent heat flux simulation in dune and meadow ecosystems (R²>0.8, RMSE<45.74 W/m2, and MAPE<26%), while the METRIC model excelled in meadow ecosystems (R2 = 0.89, RMSE = 27.79 W/m2, and MAPE = 12%). In contrast, at the regional scale, the TSEB model outperformed METRIC for sensible heat flux simulation (R2: 0.65-0.68, RMSE: 22.83-43.28 W/m2, MAPE: 14%-17%). The TSEB model ranked evapotranspiration in the order of lakes>meadow wetlands>farmland>dunes, peaking in August and following a seasonal pattern of summer>spring>autumn. Additionally, evapotranspiration varied with LAI during the pre-middle growth period and responded significantly to △T in the late vegetation period.

The spatio-temporal dynamics of ecosystem services (ESs) are essential for ecological restoration and sustainable management in arid regions. Although ESs have been extensively studied in sandy landscapes, research on the multi-model evaluation of various ESs remains limited. This study assessed the spatio-temporal quantification and driving factors of, and interrelationships among, Net Primary Productivity (NPP), Habitat Quality (HQ), Carbon Stock (C), Water Yield (WY), and Soil Retention (SR) in the Horqin Sandy Land. This assessment utilized the InVEST model, the CASA model, geographic detectors, and Spearman correlation analysis. The results indicate the following: (1) From 2000 to 2024, land use transformation in the Horqin Sandy Land was characterized by a substantial reduction in fixed sand dunes (−1047 km²) and a shift toward dryland and semi-fluid sand dunes, while semi-fixed sand dunes and forested areas expanded significantly. (2) NPP, HQ, and SR exhibited an overall increase with notable spatial improvement, whereas WY experienced a general decline. The changes in each service displayed marked differentiation in both time and space. (3) NDVI, land use and precipitation are the dominant factors of different services, and the explanatory power of the interaction among these factors is generally stronger, jointly driving the spatial pattern of ecosystem services. (4) The collaboration and trade-off relationships among services evolve dynamically over time. Among them, the transformation from trade-off to collaboration between C and WY is the most prominent, and the spatial distribution of various relationships shows significant regional heterogeneity. The research results provide a scientific basis for revealing the ecological restoration in arid areas.

Meadow grasslands are characterized by high primary productivity and are an important ecological barrier against sandstorms and desertification in northern China. The dynamic changes in reserves of soil organic carbon stocks (SOCSs), total nitrogen (TNS), and total phosphorus (TPS) in grassland ecosystems are easily disturbed by human activities. However, the effects of different treatments on the relationships among soil nutrient reserves (SOCS, TNS, and TPS) and the mechanisms underlying the effects of various key variables on changes in soil nutrient reserves remain unclear. This study investigated the changes in soil nutrient reserves in meadow grasslands in northern China after mowing (M), burning (F), and grazing (G) treatments than without any anthropogenic interference (E, control) from 2020 to 2023, as well as the vegetation and soil variables that may affect them. The results showed that compared with the control treatment, once-a-year mowing and burning significantly increased SOCS (M: 12.75%, F: 23.72%), TNS (M: 15.6%, F: 26.8%), TPS (12.4%, 27.2%) and strengthened the correlations between SOCS and TNS and between SOCS and TPS, while grazing treatments significantly reduced soil nutrient reserves (13.0%, 11.8%, 10.1%) and the correlation between soil nutrient reserves. In general, under different treatments, soil temperature was the important control variable affecting each reserve. Vegetation was also a key control variable affecting SOCS, while TNS and TPS were mainly regulated by soil factors. It should be pointed out that owing to different treatments, the key vegetation variables affecting SOCS differed notably from those affecting TNS and TPS. This study emphasized the impact of different treatments on soil nutrient reserves and their main controlling variables, providing an important theoretical basis for further optimizing and improving the scientific management strategy of grassland ecosystems.

Introduction: Understanding the response mechanisms of vegetation characteristics and soil enzyme activities to climatic factors in desertified regions is crucial. However, the relationships between vegetation, soil enzyme activities, and climatic factors in dune ecosystems under different anthropogenic disturbances remain unclear. Methods: This study, based on in situ observations conducted from 2020 to 2023 in the Horqin Sand Land, systematically elucidates the response mechanisms of vegetation characteristics and soil enzyme activities to precipitation and temperature across different types of sand dunes under enclosure (control), mowing, burning, and grazing treatments. Results: The results indicate that the effects of mowing and burning on vegetation and soil enzyme activities are strongly water-dependent. In sand dunes located in the moisture-rich dune-meadow ecotone, these treatments exhibited compensatory effects, whereas in moisture-limited semi-mobile dunes, they led to inhibitory effects. Grazing, on the other hand, significantly reduced dune vegetation biomass and soil enzyme activities by 9-45%, but markedly increased plant species richness. Correlation analysis revealed that, following mowing and burning, Poaceae species in ecotone dunes were able to rapidly utilize precipitation, exhibiting high sensitivity to rainfall. In semi-mobile dunes where shrubs and herbaceous plants coexist, species with different life forms enhanced their relationships with precipitation through stratified water use. In contrast, grazing damaged vegetation via herbivory and trampling, overall weakening the response of vegetation to both temperature and precipitation. Structural equation modeling revealed that in ecotone dunes, precipitation significantly promoted sucrose enzyme activity only under burning and grazing treatments. In fixed dunes, however, due to the low palatability of Asteraceae species, livestock trampling facilitated litter decomposition and increased fecal inputs, thereby enhancing nutrient availability, and precipitation significantly promoted vegetation growth. Discussion: Overall, different disturbances modulated the responses of vegetation and soil enzyme activities to climatic factors by regulating soil hydrothermal conditions and resource use efficiency, highlighting the critical role of water availability in controlling ecological processes in desertified regions. This study provides a theoretical basis and technical support for the conservation and restoration of sandy ecosystems.