Abstract Conflicting priorities for livestock grazing management in the context of rare plant conservation are common worldwide, especially in semiarid and arid ecosystems, where open-range livestock grazing is a primary land use. Detailed information on the interaction between livestock impacts and rare plant demography would facilitate improved management, yet this information is most often not available. In this study we examined the direct impacts of cattle trampling on dormant season survival of Astragalus holmgreniorum (Fabaceae), a globally endangered perennial spring ephemeral of the northeastern Mojave Desert, USA. Current management restricts livestock access to the dormant season, when plants are not active above-ground, but monitoring indicates possible population decline under this regime. We tagged >2100 A. holmgreniorum plants to document dormant season survival and quantified cattle trampling and other disturbance impacts in small plots at six sites with contrasting disturbance regimes. We documented disturbance impacts on survival at the site, plot, and individual plant level across two dormant season iterations. We consistently found significant negative relationships between plant dormant season survival and cattle impacts. Plants at sites with heavy cattle trampling were up to five times more likely to experience mortality than those at sites with low cattle impact. Other surface disturbances (rodent activity, human impacts, water erosion) were also quantified but contributed substantially to reduced survival in only one case of water erosion disturbance. We conclude that grazing management in A. holmgreniorum critical habitat on federal land may require modification to reduce extinction risk for this federally listed endangered species.

中文翻译：

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牛践踏增加了全球濒临灭绝的沙漠紫云英的休眠季节死亡率

摘要 在稀有植物保护背景下，牲畜放牧管理的优先事项相互冲突在世界范围内普遍存在，尤其是在半干旱和干旱生态系统中，其中露天放牧是主要的土地用途。关于牲畜影响与稀有植物人口统计之间相互作用的详细信息将有助于改进管理，但这些信息通常不可用。在这项研究中，我们研究了牛践踏对黄芪（豆科）休眠季节生存的直接影响，黄芪是美国莫哈韦沙漠东北部全球濒临灭绝的多年生春季短命植物。目前的管理限制牲畜进入休眠季节，此时植物在地上不活跃，但监测表明在这种情况下种群可能会下降。我们标记了 >2100 A。holmgreniorum 植物，以记录休眠季节的存活情况，并量化六个地点的小块地中的牛践踏和其他干扰影响，这些地点具有不同的干扰机制。我们在两个休眠季节迭代中记录了干扰对现场、地块和单个植物级别的生存的影响。我们一直发现植物休眠季节存活率与牛影响之间存在显着的负相关。与牲畜影响较小的地点相比，牲畜严重践踏地点的植物死亡的可能性要高出五倍。其他地表干扰（啮齿动物活动、人类影响、水蚀）也被量化，但仅在一种水蚀干扰情况下大大降低了存活率。我们得出结论，A 中的放牧管理。