Wildlife Health Center, University of California, Davis, CA 95616,
BMC Ecol. 2009 Nov 10;9:22. doi: 10.1186/1472-6785-9-22.
Free-ranging horses (Equus caballus) in North America are considered to be feral animals since they are descendents of non-native domestic horses introduced to the continent. We conducted a study in a southern California desert to understand how feral horse movements and horse feces impacted this arid ecosystem. We evaluated five parameters susceptible to horse trampling: soil strength, vegetation cover, percent of nonnative vegetation, plant species diversity, and macroinvertebrate abundance. We also tested whether or not plant cover and species diversity were affected by the presence of horse feces.
Horse trailing resulted in reduced vegetation cover, compacted soils, and in cases of intermediate intensity disturbance, increased plant species diversity. The presence of horse feces did not affect plant cover, but it did increase native plant diversity.
Adverse impacts, such as soil compaction and increased erosion potential, were limited to established horse trails. In contrast, increased native plant diversity near trails and feces could be viewed as positive outcomes. Extensive trailing can result in a surprisingly large impact area: we estimate that < 30 horses used > 25 km2 of trails in our study area.
北美的自由放养马（Equus caballus）被认为是野生动物，因为它们是被引入该大陆的非本地家马的后代。我们在加利福尼亚南部的沙漠中进行了一项研究，以了解野马的运动和马粪如何影响这个干旱生态系统。我们评估了五个容易受到马践踏的参数：土壤强度、植被覆盖、非本地植被比例、植物物种多样性和大型无脊椎动物丰度。我们还测试了马粪的存在是否会影响植物覆盖和物种多样性。
马的踪迹导致植被覆盖减少，土壤紧实，在中等强度干扰的情况下，植物物种多样性增加。马粪的存在并不影响植物覆盖，但它确实增加了本地植物的多样性。
不利影响，如土壤紧实和增加侵蚀潜力，仅限于已建立的马道。相比之下，在小径和粪便附近增加的本地植物多样性可以被视为积极的结果。广泛的踪迹可能会导致令人惊讶的大面积影响：我们估计，在我们的研究区域，< 30 匹马使用了 > 25 平方公里的小径。
