Grassland management impacts ecosystem functioning and is critical for livestock production and biodiversity conservation. Decreasing the stocking rate usually benefits biodiversity but also decreases production per unit area. Here, we assessed the combined effects of cattle herd and pasture size on sward structure, diet quality and daily grazing time while maintaining a constant stocking rate. The experiment was conducted over four successive years in two blocks of a species‐rich upland grassland that was continuously grazed for 5 months between May and October. Each block consisted of one 3‐ha pasture that was grazed by a group of three heifers, one 9‐ha pasture grazed by nine heifers, and one 27‐ha pasture grazed by 27 heifers. The grazed patches were discriminated using a mathematical model that for each point gave a probability of being grazed based on sward height and spatial dependence. Heifers created fewer patches and had less control over sward height in the smallest (3‐ha) plots, while no difference was found between the 9‐ and 27‐ha plots. The small heifer groups also had the shortest daily grazing time. These observations point out a risk that animal impacts on sward structure could be partly missed in grazing experiments conducted with very small groups. Estimated diet quality was unaffected by pasture size. Patch stability was frequent between two successive years but we observed a decrease in interannual patch stability as time intervals increase. Such observations are useful for calibrating spatial interaction models combining foraging behaviour and vegetation dynamics rules and enhance their predictive ability.

中文翻译：

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牧场的大小如何改变放牧牛之间的植物-草食动物的相互作用？

草地管理影响生态系统的功能，对畜牧生产和生物多样性保护至关重要。降低放养率通常有利于生物多样性，但也会降低单位面积的产量。在这里，我们评估了牛群和牧场规模对草地结构，日粮质量和每日放牧时间的综合影响，同时保持了恒定的放养率。该实验连续四年在物种丰富的高地草原的两个区块中进行，该草地在5月至10月之间连续放牧5个月。每个街区包括一个由3个小母牛组放牧的3公顷牧场，一个由9个小母牛放牧的9公顷牧场和一个由27个小母牛放牧的27公顷牧场。使用数学模型区分吃草的斑块，该数学模型基于草地高度和空间依赖性为每个点提供了放牧的可能性。在最小的（3公顷）样地中，小母牛产生的斑块较少，对草皮高度的控制也较少，而在9公顷和27公顷样地中未发现差异。小母牛群的每日放牧时间也最短。这些观察结果指出，在非常小的小组进行的放牧实验中，可能会部分忽略动物对草皮结构的影响的风险。估计的饮食质量不受牧场规模的影响。补丁稳定性在连续两年之间频繁出现，但是我们观察到年间补丁稳定性会随着时间间隔的增加而降低。