Much of the remaining native rangeland in the Great Plains in the United States is privately owned and managed for beef production, and this single priority for land use may be contributing to declining avian biodiversity through a loss of structural heterogeneity. One proposed solution is to use multiple grazing systems across ranches, under the assumption that this approach will increase heterogeneity of vegetation structure and avian diversity across the landscape. We tested the relationship between grazing systems and avian diversity in the Nebraska Sandhills during 2014 and 2015 on a landscape that included 11 management units containing 5 different grazing systems. We used multivariate models to examine the relationship of bird diversity and communities to grazing systems at the management unit scale, and we used simulations to combine empirical data from ≥1 grazing system into virtual landscapes to test the hypothesis that multiple grazing systems would result in greater heterogeneity. The 5 most common avian species made up 84% of observations (28 species), and songbird richness was 5–6 species/7.06 ha at 53% of our plots. Variation in each of the diversity measures (Shannon diversity range = 0.41–2.2, Simpson's diversity range = 0.24–0.88) was best explained by the previous dormant season's stocking rate, and richness declined by about 1 species/plot with an increase in 1 animal unit month (AUM)/ha. Songbird community structure showed the most variance between management unit, but grazing system explained little community variation. None of the simulated landscapes consistently had greater structural heterogeneity of visual obstruction reading, litter depth, and cover of bare ground than others, and there was a limited level of heterogeneity overall in the simulated landscapes. In contrast to our predictions, a variety of grazing systems did not increase heterogeneity of vegetation structure across the landscape. Thus, conservation practitioners should encourage the use of other strategies to create structural heterogeneity, such as prescribed fires and extreme stocking rates, which will support a diverse grassland songbird community (i.e., a greater variety of bird species) across the landscape. © 2020 The Wildlife Society.

中文翻译：

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内布拉斯加州沙丘的整个放牧系统中类似的鸟类群落

美国大平原上大部分剩余的原生牧场都是私有的，并管理牛肉生产，土地使用的这一优先重点可能会由于结构异质性的丧失而导致禽类生物多样性的下降。一个建议的解决方案是在牧场上使用多个放牧系统，前提是该方法将增加整个景观中植被结构的异质性和鸟类多样性。我们在2014年和2015年的内布拉斯加州桑德希尔斯地区测试了放牧系统与鸟类多样性之间的关系，该景观包括11个管理单元，其中包含5种不同的放牧系统。我们使用多元模型在管理单位规模上研究了鸟类多样性和群落与放牧系统之间的关系，并且我们使用模拟将≥1个放牧系统的经验数据组合到虚拟景观中，以检验多个放牧系统将导致更大异质性的假设。5种最常见的鸟类占观测值的84％（28种），而在我们的样地中，鸣鸟的丰富度为5-6种/7.06公顷。上一个休眠季节的放养率最好地解释了每种多样性测度的变化（香农的多样性范围= 0.41–2.2，辛普森的多样性范围= 0.24–0.88），并且随着一只动物的增加，其丰富度下降了大约1种/地段。单位月（AUM）/公顷。鸣禽群落结构显示出管理单位之间的差异最大，但放牧系统解释的群落差异很小。没有一个模拟景观在视觉障碍物阅读，垫料深度和裸露地面的覆盖上始终具有比其他任何一个更大的结构异质性，并且在整个模拟景观中整体异质性水平有限。与我们的预测相反，各种放牧系统并未增加整个景观中植被结构的异质性。因此，保护​​从业人员应鼓励使用其他策略来创建结构异质性，例如规定的火灾和极端的放养率，这将支持整个景观上的多种草地鸣禽群落（即种类更多的鸟类）。©2020野生动物协会。与我们的预测相反，各种放牧系统并未增加整个景观中植被结构的异质性。因此，保护​​从业人员应鼓励使用其他策略来创建结构异质性，例如规定的火灾和极端的放养率，这将支持整个景观上的多种草地鸣禽群落（即种类更多的鸟类）。©2020野生动物协会。与我们的预测相反，各种放牧系统并未增加整个景观中植被结构的异质性。因此，保护​​从业人员应鼓励使用其他策略来创建结构异质性，例如规定的火灾和极端的放养率，这将支持整个景观上的多种草地鸣禽群落（即种类更多的鸟类）。©2020野生动物协会。遍布整个鸟类的鸟类种类）。©2020野生动物协会。遍布整个鸟类的鸟类种类）。©2020野生动物协会。