Meadow ecosystems have important ecological functions and support socioeconomic services, yet are subject to multiple stressors that can lead to rapid degradation. In the Sierra Nevada of the western USA, recreational pack stock (horses and mules) use in seasonally wet mountain meadows may lead to soil trampling and meadow degradation, especially when soil water content is high and vegetation is developing. In order to improve the ability to predict meadow vulnerability to soil disturbance from pack stock use, we measured soil resistance (SR), which is an index of vulnerability to trampling disturbance, at two spatial scales using a stratified-random sampling design. We then compared SR to several soil and vegetation explanatory variables that were also measured at the two spatial scales: plant community type (local scale) and topographic gradient class (meadow scale). We found that local-scale differences in drivers of SR were contingent on the meadow scale, which is important because multiple spatial scale evaluation of ecological metrics provides a broader understanding of the potential controls on ecological processes than assessments conducted at a single spatial scale. We also found two contrasting explanatory models for drivers of SR at the local scale: (1) soil gravimetric water content effects on soil disaggregation and (2) soil bulk density and root mass influence on soil cohesion. Soil resistance was insufficient to sustain pack stock use without incurring soil deformation in wet plant communities, even when plant cover was maximal during a major drought. Our study provides new information on seasonally wet meadow vulnerability to trampling by pack stock animals using multi-scale drivers of SR, including the contrasting roles of soil disaggregation, friction, and cohesion. Our work aims to inform meadow management efforts in the Sierra Nevada and herbaceous ecosystems in similar regions that are subject to seasonal soil saturation and livestock use.

中文翻译：

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土壤阻力的多尺度驱动因素预测，美国内华达山脉季节性湿润的草地很容易被成群的牲畜践踏

草甸生态系统具有重要的生态功能并支持社会经济服务，但受到多种压力的影响，可能导致快速退化。在美国西部的内华达山脉，季节性湿润的高山草甸中使用的休闲装种群（马和and子）可能会导致土壤践踏和草甸退化，尤其是在土壤含水量高且植被正在发育的时候。为了提高预测草甸利用包装动物对土壤干扰的脆弱性的能力，我们使用分层随机抽样设计在两个空间尺度上测量了土壤抗性（SR），这是践踏干扰的脆弱性指标。然后，我们将SR与几种土壤和植被解释变量进行了比较，这些变量也在两个空间尺度上进行了测量：植物群落类型（局部尺度）和地形梯度类（草地尺度）。我们发现，SR驱动力的局部尺度差异取决于草地尺度，这很重要，因为与在单个空间尺度上进行的评估相比，对生态指标进行多空间尺度的评估可以更广泛地了解生态过程的潜在控制。我们还发现了两个相反的解释模型，这些模型在局部尺度上是SR的驱动因素：（1）土壤重量水分含量对土壤分解的影响；（2）土壤容重和根质量对土壤凝聚力的影响。即使在大干旱期间植物覆盖最大，土壤抵抗力也不足以维持包装纸的使用，而不会在潮湿的植物群落中引起土壤变形。我们的研究提供了有关季节性湿润草甸易受杂种动物利用SR多尺度驱动者践踏的脆弱性的新信息，包括土壤分解，摩擦和凝聚力的对比作用。我们的工作旨在为内华达山脉的草地管理工作和类似地区的季节性土壤饱和度和牲畜使用情况下的草本生态系统提供信息。