Search Results (3)

This study systematically analyzes the multi-layered regulatory mechanisms of grazing on soil nitrogen and phosphorus cycling functions, based on the combined effects of different grazing strategies and plant community spatial patterns in alpine grasslands. A controlled mixed grazing experiment with moderate intensity was conducted on a livestock system adaptive management platform in the region surrounding Qinghai Lake on the Qinghai–Tibet Plateau, China. The experimental treatments included yak-only grazing (YG), Tibetan sheep-only grazing (SG), mixed grazing of yak and Tibetan sheep (MG), and no grazing (CK). The study quantitatively assessed the soil microbial nitrogen and phosphorus cycling functional genes in the rhizosphere of dominant species, including the Carex alatauensis and Potentilla acaulis, under different grazing intensities. The aim was to explore the effects of grazing strategy and clusters of dominant species on soil nitrogen and phosphorus cycling and their regulatory mechanisms. The results of this study show that, in the nitrogen cycle, grazing led to a decrease in total nitrogen (TN) content and an increase in ammonium nitrogen content in the dominant species communities. The MG treatment significantly enhanced the abundance of key nitrogen metabolism genes, such as ureC and gs. In the phosphorus cycle, most grazing treatments increased total phosphorus content, but changes in available phosphorus were variable among plant clusters. The MG and SG treatments significantly increased the abundance of functional genes such as aphA, ugpB, and phnW. Compared to the relatively stable soil nitrogen and phosphorus content, the abundance of functional genes exhibited significantly higher variability across different grazing treatments. The clusters of Potentilla acaulis maintained nutrient stability by enhancing nitrogen assimilation and phosphorus uptake, while the clusters of Carex alatauensis promoted ammonium nitrogen accumulation through a conservative strategy. The results indicate that grazing influences nitrogen and phosphorus availability by altering nutrient input and disturbance modes, while plant clusters optimize cycling through differential regulation of microbial functional genes in the community. Both factors jointly regulate nitrogen and phosphorus cycling in Alpine Grassland soils. Mixed grazing exhibited significant advantages in promoting nitrogen retention, enhancing phosphorus activation, and improving plant-microbe interactions, reflecting a comprehensive facilitation of nutrient cycling stability in alpine grasslands. These findings provide important theoretical insights for nutrient cycling management and sustainable grazing practices in alpine grasslands. Full article

To clarify the ecological mechanisms underlying the succession of artificial grasslands to native alpine meadows and systematically reveal the patterns of ecological restoration in artificial grasslands in the Qinghai–Tibet Plateau, this study provides a theoretical basis for alpine meadow ecological restoration. In this study, artificial grassland and degraded grassland (CK) with different restoration years (20 years, 16 years, 14 years, and 2 years) in the Qinghai–Tibet Plateau were taken as research objects. We focused on the tillering characteristics, patch number, community structure evolution, and soil properties of the dominant species, C. alatauensis, and systematically explored the ecological restoration law by comparing and analyzing ecological indicators in different restoration years. The results showed the following: (1) With the extension of restoration years, the asexual reproduction ability of C. alatauensis was enhanced, the patches became large, and aboveground/underground biomass significantly accumulated. (2) Community structure optimization meant that the coverage and biomass of Cyperaceae plants increased with restoration age, while those of Poaceae plants decreased. The diversity of four species in 20A of restored grasslands showed significant increases (10.71–19.18%) compared to 2A of restored grasslands. (3) Soil improvement effect: The contents of soil organic carbon (SOC), total phosphorus (TP), nitrate nitrogen (NN), and available phosphorus (AP) increased significantly with the restoration years (in 20A, the SOC content in the 0–10 cm soil layer increased by 57.5% compared with CK), and the soil pH gradually approached neutrality. (4) In artificial grasslands with different restoration ages (20A, 16A, and 14A), significant or highly significant correlations existed between C. alatauensis tiller characteristics and community and soil properties. In conclusion, C. alatauensis in artificial grasslands drives population enhancement, community succession, and soil improvement through patch expansion. Full article

Modeling the current distribution of and predicting suitable habitats for threatened species support the species conservation and restoration planning process. Therefore, the purpose of this study was to model the actual distribution and predict environmentally suitable habitats for Carex alatauensis S.R.Zhang 2015, a locally threatened native grass species on the Qinghai–Tibet Plateau. To realize this objective, based on the geographical samples within the natural distribution of C. alatauensis, the dominant climatic factors in its potential distribution range were analyzed using the maximum entropy (MaxEnt) model. The results showed that the average values of the area under the receiver operating characteristic curve (AUC) of the training data were 0.833 ± 0.044, which indicated that the accuracy of the MaxEnt model was pretty high for modeling potential distribution regions of C. alatauensis. The combined results from the Jackknife test and the presented contribution of environmental variables revealed that the annual precipitation, the growth season precipitation, and the precipitation of the driest month were the key climatic factors that restricted the distribution of C. alatauensis on the Qinghai–Tibet Plateau. It is predicted that the potential distribution area of C. alatauensis on the Qinghai–Tibet Plateau is 1.96 × 10⁶ km², and the most suitable area is 3.7 × 10⁵ km², mainly located in the Qilian Mountains, the Himalayas, and the Qingtanggula Mountains. Full article