International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.6, 267-276 http://ecoevopublisher.com/index.php/ijmec 274 adaptation (Borer and Stevens, 2022). The aridification effect: Drought has a more significant impact on grasslands. Microbial growth is inhibited, enzyme activity decreases, soil animals are highly sensitive to drought, their diversity declines, the mineralization of litter slows down, and the nitrogen cycle is severely restricted. Rainfall after the end of drought often triggers "pulsed mineralization", resulting in an increase in short-term nitrogen loss. Changes in precipitation patterns, with concentrated precipitation but extended intervals, will intensify the dry-wet cycle, leading to a larger microbial deading-regeneration cycle and causing strong fluctuations in carbon-nitrogen mineralization (Liu et al., 2023). 6.4 Ecological effects of invasive alien species Alien species can profoundly influence the nutrient cycle of grasslands by altering plant communities, litter mass and soil microbial structure. High-yield invasive grass species (such as some exotic grasses) increase the input of litter but with poor quality, which slows down decomposition. Invasive leguminous species increase nitrogen input and change the direction of the nitrogen cycle, causing "nitrogen eutrophication" in the system. Root detoxification substances may inhibit the local microbial community and alter the structure of enzyme activity. In poorly managed areas, alien species often push the system into a new homeostasis, making it difficult to restore the original carbon-nitrogen balance (Rui et al., 2025). 7 Grassland Nutrient Cycle Regulation and Ecological Restoration Strategies 7.1 Rational grazing and grassland management The most crucial issue in grassland management is to regulate the intensity of grazing and keep it within the ecological carrying capacity. Effective strategies include implementing a rotational grazing system to reduce local continuous trampling, setting grazing rest periods to give plants time to recover, adjusting the amount of livestock carried according to productivity, and avoiding "overgrazing". Fecal management promotes the return of local nutrients. Rational grazing can maintain the diversity of plant communities, make the litter input structure more stable, and thereby maintain the long-term nutrient cycle function (Hou et al., 2024). 7.2 Enhance soil organic matter and microbial functions Increasing soil organic matter is a key strategy for enhancing the resilience of grasslands. The main measures include increasing the input of litter (such as reducing fire and avoiding overgrazing), promoting root growth, enhancing underground carbon input, applying organic fertilizers or biochar, improving soil aggregate structure, and restoring microbial diversity, such as inoculating local dominant fungi or pro-growth bacteria. Improving microbial functions can enhance carbon stability, enzyme activity and mineralization efficiency (Song et al., 2023). 7.3 Comprehensive measures for restoring degraded grassland The restoration of degraded grassland should adopt systematic measures rather than single intervention. Enclosure and cultivation, which refers to restricting human activities and allowing plants to recover naturally, is a commonly used and effective method in arid grasslands. Reseeding refers to the introduction of drought-tolerant, nitrogen-fixing or dominant local grass species in severely degraded areas, which can accelerate the recovery of vegetation structure. Topsoil protection and soil and water conservation measures reduce wind erosion and water erosion through biological sand fixation, stone grids and micro-terrain modification. Soil structure restoration, mechanical loosening, vegetation cover and biological measures jointly improve soil aeration and aggregate stability (Yu et al., 2022). 7.4 Establish a sustainable grassland management model Future grassland management requires the establishment of a long-term monitoring and adaptive management system. Data-based decision-making integrates remote sensing, monitoring stations, phenology and soil indicators. Encourage residents in pastoral areas to participate in grazing management and ecological protection. Provide an ecological compensation system to make conservation actions economically incentivized. Cross-regional collaborative management is particularly suitable for contiguous grasslands such as those in Central Asia and the
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