The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-year-old C. intermedia plantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil “fertile islands” were formed, and the “fertile islands” were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous shrub.

Considering the variations in carbon concentrations among different plant components can significantly improve carbon storage estimates. The aim of this study was to estimate the biomass and carbon storage and sequestration in Caragana intermedia Kuang et H. C. Fu plantations for six different ages. The biomass and carbon sequestration in shrub biomass were quantified using a destructive method that involved analysing the carbon concentrations in the leaves, branches, stem bark, stem wood, roots > 5 mm, 2 mm < roots ≤ 5 mm, and roots ≤ 2 mm. The biomass and biomass carbon density of the C. intermedia plantations increased with the age of the stands. The biomass carbon density of the woody components was at its maximum in the 30-year-old plantation (14.27 ± 2.71 t·ha⁻¹), indicating that C. intermedia plantations in alpine sandy land are an important carbon pool. The carbon accumulation rate of the woody components was higher during the early stages of plantation development. The carbon concentrations differed significantly among the components but changed only slightly with the stand age. The weighted mean carbon concentration of the woody components, which was found to be 44%, must be considered when estimating the long-term carbon pools in C. intermedia plantations.

Grazing impacts soil enzyme activities by changing soil conditions and microbial functions. Yet, the specific effects of grazing on soil enzymes in different northeastern China forest-steppe vegetation types remain poorly understood. To examine this, catalase (CA), urease (UA), and cellulase (CEA) activities were measured in different vegetation types (NS, MF, CP, GL) under both grazing and non-grazing conditions. Soil microbial biomass carbon and nitrogen (MBC and MBN) and other soil factors were also studied to gauge their impact on enzyme activities. The results indicated that enzyme activities were influenced by grazing, soil nutrient levels, mineralization, and microbial biomass carbon and nitrogen content. Grazing exerted the most significant influence on UA. CEA was predominantly affected by the content of biomass nitrogen and soil mineralization. CA, on the other hand, was primarily influenced by soil nutrient levels. Grazing influenced enzyme activities differently based on vegetation type. Under grazing, CA showed higher values in NS, MF, CP, and GL (4.09, 2.42, 3.26, and 3.90 mL 0.1 mol L⁻¹ KMnO₄ g⁻¹ soil 20 min⁻¹, respectively) with increases ranging from 32.52% to 505.00% (p < 0.05). Additionally, UA values were significantly higher in MF and CP (0.24 and 0.59 mg NH₄⁺-N g⁻¹ soil d⁻¹, respectively) with increases of 66.67% and 156.00%, while UA and CEA were lower in GL, showing reductions of 78.79% and 166.67% (p < 0.05) (0.33 NH₄⁺-N g⁻¹ soil d⁻¹ and 0.06 mg glucose g⁻¹ soil 72 h⁻¹, respectively) under grazing conditions. These findings underscore the importance of vegetation types in the grazing effects on soil enzymes at the forest-steppe ecotone and suggest that further efforts should be made to strengthen grassland grazing management to mitigate negative impacts on soil environmental health.

There is a dearth of research regarding the windbreak and sand stabilization functions of Caragana liouana shelter forests in the Gonghe Basin of the Qinghai-Tibet Plateau. Therefore, the aim is to elucidate the patterns of near-surface wind–sand activity in artificial Caragana liouana forests of varying ages and mixed forests of different configurations in alpine sandy areas. Additionally, this research seeks to clarify the windbreak and sand fixation effects of these forests. To this end, we have selected artificial forests of Caragana liouana of varying ages (10-year-old pure Caragana liouana forest (10aZJ-C), 17-year-old pure Caragana liouana forest (17aZJ-C), 37-year-old pure Caragana liouana forest (3aZJ-C)) and shrub mixed forests of different mixing modes (10-year-old Caragana liouana and Caragana korshinskii mixed forest (10aNZ-HJ), 10-year-old Caragana liouana and Artemisia desertorum mixed forest (10aSZ-HJ), an 10-year-old Caragana liouana and Salix cheilophila mixed forest (10aWZ-HJ)) within the Sand Control Station of Shazhuyu Village in the Gonghe Basin of the Qinghai-Tibet Plateau as the research subjects. Naked sand dunes were used as the control plot (CK), and through field observations of the wind speed profile, sand transport rate, and micro-topographic changes of each stand plot, we analyzed the wind–sand flow structure characteristics and sand transport process of Caragana liouana of different ages and their mixed forests, eventually proposing suitable afforestation configuration modes for the alpine sand area of the Gonghe Basin in Qinghai. The findings indicate that the wind speed profile within each stand plot follows a linear distribution pattern. Compared to naked dune land, the windbreak effect of each plot decreases as the height from the ground increases. Among them, the 10aWZ-HJ plot significantly alters the wind speed profile and has a substantial windbreak effect; at a height of 200 cm, the windbreak effect can still reach 41.27%. The sand transport rate of each plot fits into an exponential function relationship, with the correlation coefficients (R²) of the fitting equations for each plot all exceeding 0.95 and significantly lower than the control plot, suggesting vegetation can effectively reduce near-surface sand transport. The sand-fixing effects at the height of 0–45 cm from the ground in each plot are as follows: 37aZJ-C > 17aZJ-C > 10aWZ-HJ > 10aNZ-HJ > 10aZJ-C > 10aSZ-HJ. Overall, all plots indicate a state of accumulation. The 10aWZ-HJ plot has the largest relative accumulation area at 88.00%, and the highest average intensity of wind erosion and accumulation at 1.11. Taking into account the stability of the stand and the total protection time, this study suggests that it is suitable to mainly use mixed forests of Salix cheilophila and Caragana liouana in the alpine sand area of the Qinghai-Tibet Plateau. The results of this study can provide a theoretical basis for the construction of windbreak and sand-fixing forests in alpine sand areas.

Shrubs are the main species in desert ecosystems. Better understanding shrubs fine root dynamics and its contribution to soil organic carbon (SOC) stocks can improve the accuracy of carbon sequestration estimation and provide basic data for the calculation of carbon sequestration potential. The ingrowth core method was used to investigate the fine root (< 1 mm in diameter) dynamics of Caragana intermedia Kuang et H. C. Fu plantation with different age (4-, 6-, 11-, 17-, and 31-year-old) in Gonghe Basin of the Tibetan Plateau, and the annual fine root mortality was used for calculation the annual carbon input to SOC pool. The results showed that fine root biomass, production, and mortality first increased and then decreased as the plantation age increased. Fine root biomass peaked in 17-year-old plantation, production and mortality peaked in 6-year-old plantation, and turnover rate of 4- and 6-year-old plantations were significantly higher than other plantations. Fine root production and mortality were negative correlated with soil nutrients at depth of 0–20 and 20–40 cm. The variation range of carbon input by fine root mortality across different plantation age at 0–60 cm soil depth was 0.54–0.85 Mg ha^-1 year^-1, accounting for 2.40–7.54% of the SOC stocks. C. intermedia plantation has a strong carbon sequestration potential from long time scale. Fine roots regenerate faster in young stands and lower soil nutrients environment. Our results suggest that the influences of plantation age and soil depth should be taken into account when calculating the contribution of fine root to SOC stocks in desert ecosystems.