Department of Biology, University of Miami, 1301 Memorial Drive, Coral Gables, Florida, 33146, USA.
Archbold Biological Station, 123 Main Drive, Venus, Florida, 33960, USA.
Ecol Appl. 2019 Dec;29(8):e01976. doi: 10.1002/eap.1976. Epub 2019 Aug 19.
Pastureland currently occupies 26% of Earth's ice-free land surface. As the global human population continues to increase and developing countries consume more protein-rich diets, the amount of land devoted to livestock grazing will only continue to rise. To mitigate the loss of global biodiversity as a consequence of the ever-expanding amount of land converted from native habitat into pastureland for livestock grazing, an understanding of how livestock impact wildlife is critical. While previous reviews have examined the impact of livestock on a wide variety of taxa, there have been no reviews examining how global livestock grazing affects amphibians. We conducted both an empirical study in south-central Florida examining the impact of cattle on amphibian communities and a quantitative literature review of similar studies on five continents. Our empirical study analyzed amphibian community responses to cattle as both a binary (presence/absence) variable, and as a continuous variable based on cow pie density. Across all analyses, we were unable to find any evidence that cattle affected the amphibian community at our study site. The literature review returned 46 papers that met our criteria for inclusion. Of these studies, 15 found positive effects of livestock on amphibians, 21 found neutral/mixed effects, and 10 found negative effects. Our quantitative analysis of these data indicates that amphibian species that historically occurred in closed-canopy habitats are generally negatively affected by livestock presence. In contrast, open-canopy amphibians are likely to experience positive effects from the presence of livestock, and these positive effects are most likely to occur in locations with cooler climates and/or greater precipitation seasonality. Collectively, our empirical work and literature review demonstrate that under the correct conditions well-managed rangelands are able to support diverse assemblages of amphibians. These rangeland ecosystems may play a critical role in protecting future amphibian biodiversity by serving as an "off-reserve" system to supplement the biodiversity conserved within traditional protected areas.
目前，牧场占据了地球无冰陆地表面的 26%。随着全球人口的持续增长和发展中国家对高蛋白饮食的需求增加，用于牲畜放牧的土地面积只会继续增加。为了减轻因将更多的原生栖息地转化为牲畜放牧的牧场而导致的全球生物多样性丧失，了解牲畜对野生动物的影响至关重要。虽然之前的综述已经研究了牲畜对各种分类群的影响，但没有综述研究全球牲畜放牧如何影响两栖动物。我们在佛罗里达州中南部进行了一项实证研究，研究了牛对两栖动物群落的影响，并对五大洲的类似研究进行了定量文献综述。我们的实证研究分析了牛对两栖动物群落的影响，既作为二元（存在/不存在）变量，也作为基于牛粪密度的连续变量。在所有分析中，我们都没有发现任何证据表明牛对我们研究地点的两栖动物群落有影响。文献综述返回了 46 篇符合我们纳入标准的论文。在这些研究中，15 项研究发现牲畜对两栖动物有积极影响，21 项研究发现中性/混合影响，10 项研究发现消极影响。我们对这些数据的定量分析表明，历史上生活在封闭树冠栖息地的两栖物种通常会受到牲畜存在的负面影响。相比之下，开放树冠的两栖动物很可能会受到牲畜存在的积极影响，这种积极影响最可能发生在气候较凉爽和/或降水季节性较强的地方。总的来说，我们的实证工作和文献综述表明，在正确的条件下，管理良好的牧场能够支持多样化的两栖动物群落。这些牧场生态系统可能通过充当“非保护区”系统来补充传统保护区内保护的生物多样性，在保护未来的两栖动物生物多样性方面发挥关键作用。
