State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu, PR China.
Bureau of Quality and Technical Supervision Liangzhou Branch, Wuwei, Gansu, PR China.
J Environ Manage. 2023 Dec 15;348:119184. doi: 10.1016/j.jenvman.2023.119184. Epub 2023 Oct 11.
Grazing and climate change both contribute to diversity loss and productivity fluctuations. Sensitive climate conditions and long-term grazing activities have a profound influence on community change, particularly in high-altitude mountain grassland ecosystems. However, knowledge about the role of long-term continuous grazing management on diversity, productivity and the regulation mechanisms in fragile grassland ecosystems is still rudimentary. We conducted a long-term grazing experiment on an alpine typical steppe in the Qilian Mountains to assess effects of grazing intensity on soil, diversity, productivity and the regulation mechanisms. Plants and soil were sampled along grazing gradients at different distances from the pasture entrance (0, 0.3, 0.6, 0.9, 1.2 and 1.5 km) under the non-growing (WP) and the growing season grazing pasture (SAP). The results revealed that community diversity and biomass did not change significantly on a time scale, while the concentration of soil organic carbon and total phosphorus increased significantly. Heavy grazing (0-0.3 km) decreased community diversity and biomass. Grazing increased soil chemical properties in heavy grazed areas of WP, while the opposite was recorded in SAP. Soil chemical properties explained the largest variances in community diversity and community biomass. The prediction model indicates that grazing in WP mainly affects community diversity through soil chemical properties, and promotes a positive correlation between community diversity and community biomass; in SAP, the direct effect of grazing gradients on community diversity and biomass is the main pathway, but not eliminating the single positive relationship between diversity and biomass, which means that diversity can still be used as a potential resource to promote productivity improvement. Therefore, we should focus on the regulation of soil chemical properties in WP, such as the health and quality of soil, strengthening its ability to store water, sequester carbon and increase nutrients; focus on the management of livestock in SAP, including providing fertilizer and sowing to increase diversity and production in heavily grazed regions and reducing grazing pressure through regional rotational grazing. Ultimately, we call for strengthening the stability and sustainability of ecosystems through targeted and active human intervention in ecologically sensitive areas to cope with future grazing pressures and climate disturbances.
放牧和气候变化都会导致生物多样性丧失和生产力波动。敏感的气候条件和长期放牧活动对群落变化有深远的影响，特别是在高海拔山地草原生态系统中。然而，关于长期连续放牧管理对脆弱草原生态系统多样性、生产力和调节机制的作用的知识仍然很初级。我们在祁连山进行了一项高寒典型草原的长期放牧实验，以评估放牧强度对土壤、多样性、生产力和调节机制的影响。在非生长季（WP）和生长季放牧（SAP）条件下，在距牧场入口不同距离（0、0.3、0.6、0.9、1.2 和 1.5 公里）处沿放牧梯度采集植物和土壤样本。结果表明，在时间尺度上，群落多样性和生物量没有显著变化，而土壤有机碳和总磷浓度显著增加。重度放牧（0-0.3 公里）降低了群落多样性和生物量。放牧增加了 WP 重度放牧区的土壤化学性质，而在 SAP 则相反。土壤化学性质解释了群落多样性和群落生物量的最大方差。预测模型表明，WP 中的放牧主要通过土壤化学性质来影响群落多样性，并促进群落多样性与群落生物量之间的正相关关系；在 SAP 中，放牧梯度对群落多样性和生物量的直接影响是主要途径，但并未消除多样性与生物量之间的单一正相关关系，这意味着多样性仍然可以作为提高生产力的潜在资源。因此，我们应该关注 WP 中土壤化学性质的调节，如土壤的健康和质量，加强其蓄水、固碳和增加养分的能力；关注 SAP 中牲畜的管理，包括施肥和播种以增加重度放牧区的多样性和产量，并通过区域轮牧减少放牧压力。最终，我们呼吁通过有针对性和积极的人为干预来加强生态敏感地区生态系统的稳定性和可持续性，以应对未来的放牧压力和气候干扰。
