放牧强度对内蒙古典型草原群落结构和家畜生产性能的影响

认识放牧对草地植物群落结构和家畜生产性能的影响是修复放牧退化草地和制定可持续放牧体系的理论基础。本研究在内蒙古锡林郭勒典型草原开展了基于草地放牧留茬高度的适应性放牧实验，连续4年监测了无牧(NG)、轻牧(LG)、中牧(MG)和重牧(HG)条件下草地植物群落的变化和家畜生产性能，分析其对放牧强度的响应。结果表明：与NG相比，HG显著降低了优势种的相对生物量，提高了伴生种的相对生物量(P<0.05);LG和MG处理下主要提高了优势种的生产力，而在HG处理主要提高了伴生种的生产力；在所研究的典型草原采用适应性放牧方式下，中度放牧可获得最佳的草地植物生产和家畜生产性能。研究为制定合理的草原放牧制度、促进草地群落结构优化和草畜平衡发展提供了理论依据。

Effects of Grazing Intensity on Community Structure and Livestock Productivity in A Typical Steppe of Inner Mongolia

Understanding the effects of grazing on plant community structure and livestock performance is a basis for restoring the degraded grassland and developing a sustainable grazing management. We conducted a grazing experiment in a typical steppe grassland in Xilingol region of Inner Mongolia, to investigate the response of steppe community structure and grazing animal performance to grazing intensities in an adaptive grazing management system. The experiment was a random block design with 4 grazing intensities, i.e., nil grazing (NG), light grazing (LG), moderate grazing (MG) and heavy grazing (HG), replicated by four times. The grassland was rotationally grazed three times in plant growing season each year, and each grazing stopped when grassland residual height was about 6 cm. We monitored the plant community composition and structure, and the feeding behavior and bodyweight gain of grazing sheep over a 4-year experimental period (2017 to 2020). The results showed that:Compared with NG, HG significantly decreased the relative biomass of dominant species but increased that of subordinate species in community (P<0.05);Grazing enhanced the grassland community productivity, and the enhancement was mainly a consequence of the productivity increase of dominant species under LG and MG, but of subordinate species under HG;In the adaptive management system, the designed MG has the best grassland structure and animal production performance. Our study provides the theoretical basis for formulating rational grazing system, promoting a balanced development with both grassland community structure and livestock production considered.