Natural grasslands in southern Brazil are ecosystems that are naturally adapted to grazing. Despite the productivity and ecological relevance of these ecosystems, the effects of grazing intensity on their soil quality are still underexplored. This work aimed to determine whether increasing the grazing intensity would jeopardize the soil structure in a natural highland grassland in southern Brazil. Pastures were evaluated at four pregrazing canopy heights, 0.12, 0.20, 0.28 and 0.36 m, with Andropogon lateralis Nees as the reference species, and in one ungrazed control area. The pastures were intermittently stocked, and the postgrazing heights corresponded to 60% of the pregrazing targets (i.e., the postgrazing heights were 0.072, 0.12, 0.168 and 0.216 m). The experiment started in 2015 and was conducted for three years, with evaluations of soil physical properties performed in the final year. Forage growth and grazing were concentrated from October to May; during the winter, no grazing occurred for a period of approximately 4 months. The soil structure was evaluated at two points: after the end of the 2017/2018 grazing season, in June, and after the winter period, in October. Regardless of the canopy height, the presence of grazing animals increased the degree of compaction at the soil surface (0.0–0.05 m) to an intermediate level immediately after grazing, did not disaggregate the soil or change its carbon and nitrogen stocks, and increased soil macroporosity and water infiltration compared to those in the exclusion area (control). Increasing the grazing intensity (i.e., increasing the grazing frequency, corresponding to lower pregrazing canopy heights) increased the soil macroporosity and water infiltration rate, decreased the soil moisture and increased the soil penetration resistance. Except at the 0.12 m canopy height, the exclusion of grazing for 4 months allowed the soil water infiltration in the grazed plots to return to a level similar to that in the exclusion area. We conclude that there are a wide range of grazing intensities (corresponding to canopy heights of 0.12–0.36 m) that do not jeopardize the soil structural quality in highland grasslands. Furthermore, it was not possible to determine whether canopy heights below 0.12 m would disrupt the synergism at the soil-plant-animal interface in these natural ecosystems.

巴西南部的天然草原是自然适应放牧的生态系统。尽管这些生态系统具有生产力和生态相关性，但放牧强度对其土壤质量的影响仍未得到充分探索。这项工作旨在确定增加放牧强度是否会危及巴西南部天然高原草原的土壤结构。在四个放牧前冠层高度（0.12、0.20、0.28 和 0.36 m）对牧场进行了评估，其中有AndropogonlateralisNees 作为参考物种，并在一个未放牧的控制区域。牧场间断放牧，放牧后高度相当于放牧前目标的60%（即放牧后高度分别为0.072、0.12、0.168和0.216 m）。该试验于 2015 年开始，进行了三年，最后一年进行了土壤物理性质的评估。牧草生长和放牧集中在10-5月；在冬季，大约有 4 个月没有放牧。土壤结构在两个点进行评估：2017/2018 放牧季节结束后的 6 月和冬季后的 10 月。无论冠层高度如何，放牧动物的存在都会增加土壤表面的压实程度（0.0-0. 05 m) 在放牧后立即达到中等水平，与禁区（对照）相比，没有分解土壤或改变其碳和氮储量，并且增加了土壤大孔隙度和水渗透。增加放牧强度（即增加放牧频率，对应于较低的预放牧冠层高度）增加土壤大孔隙度和水分入渗率，降低土壤水分并增加土壤渗透阻力。除冠高0.12 m外，禁牧4个月，放牧地块土壤水分入渗量恢复到禁区水平。我们得出的结论是，放牧强度范围很广（对应于 0.12-0 的冠层高度。36 m) 不会危害高原草原土壤结构质量。此外，无法确定低于 0.12 m 的冠层高度是否会破坏这些自然生态系统中土壤-植物-动物界面的协同作用。