Institute of Botany, University of Basel, Schönbeinstrasse 6, 4056 Basel, Switzerland.
Oecologia. 2013 Mar;171(3):693-703. doi: 10.1007/s00442-012-2583-6. Epub 2013 Jan 22.
While exerting no obvious function under "average" environmental conditions, the presence of certain plant specialists becomes crucial in the event of a complete failure of a community due to severe disturbance such as landslides. Plants capable of growing at erosion edges may act as potential edge-engineers by coping with unstable ground and stabilizing the soil with their roots. We hypothesized that life conditions at erosion edges select for a particular set of specialists or species with specific traits, the identification of which was the aim of the study. Across 17 small-scale transects (0.40 × 1.60 m) from intact meadows to landslide edges (Ursern Valley, Swiss Alps, c. 1,600 m a.s.l.), we quantified plant species abundance by the point intercept method and characterized growth conditions based on Landolt's indicator values, leaf δ(13)C, and volumetric soil moisture in the uppermost soil layers. We observed a clear change of plant species composition and relative abundance from the meadow to the edge, presumably induced by the 25 % lower soil moisture and microclimatic exposure. Species richness at the edge was two-thirds of that in the meadow, but was positively correlated with species richness of the adjacent meadow. Species with "edge-preference" had either (1) rolled or festucoid leaves like Festuca spp., Avenella flexuosa and Nardus stricta, or (2) small, scleromorphic leaves like Vaccinium vitis-idaea, Calluna vulgaris and Thymus ssp. Graminoids with rolled/festucoid leaves were found to be the most dominant edge-specialists. The grass Festuca valesiaca s.l. emerged as the most dominant plant species at the edge, having an 11-times higher cover at the edge than in the meadow. In this montane grassland, a single species contributes to the stabilization of erosion edges and may be regarded as a potential keystone species for slope stability and regeneration after landslides even its role has not so far been established.
在“平均”环境条件下，某些植物专家的存在并没有明显的作用，但在由于滑坡等剧烈干扰而导致群落完全失败的情况下，它们的存在就变得至关重要。能够在侵蚀边缘生长的植物可以通过应对不稳定的地面并用它们的根来稳定土壤，从而充当潜在的边缘工程师。我们假设，侵蚀边缘的生活条件会选择具有特定特征的一组特定的专家或物种，本研究的目的就是确定这些特征。在从完整草地到滑坡边缘的 17 个小尺度样带（0.40×1.60 m，乌尔斯恩山谷，瑞士阿尔卑斯山，海拔约 1600 m）上，我们通过点截距法量化了植物物种丰度，并根据 Landolt 的指标值、叶片 δ(13)C 和最上层土壤的体积土壤湿度来描述生长条件。我们观察到从草地到边缘的植物物种组成和相对丰度发生了明显变化，这可能是由于土壤湿度降低了 25%和微气候暴露造成的。边缘的物种丰富度是草地的三分之二，但与相邻草地的物种丰富度呈正相关。具有“边缘偏好”的物种要么像 Festuca spp.、Avenella flexuosa 和 Nardus stricta 一样具有卷曲或 festucoid 叶，要么像 Vaccinium vitis-idaea、Calluna vulgaris 和 Thymus ssp. 一样具有小而硬化的叶。具有卷曲/ festucoid 叶的禾本科植物被发现是最主要的边缘专家。禾本科植物 Festuca valesiaca s.l. 成为边缘最主要的植物物种，其在边缘的盖度比在草地中高出 11 倍。在这个高山草原中，单个物种有助于侵蚀边缘的稳定，并且可以被视为边坡稳定性和滑坡后再生的潜在关键物种，尽管其作用尚未得到确定。
