Department of Earth and Environmental Sciences, University of Pavia, Via S. Epifanio 14, 27100 Pavia, Italy.
DAFNAE Department, University of Padova, Viale dell'Università 16, 35020 Legnaro (PD), Italy.
Sci Total Environ. 2018 Oct 15;639:633-639. doi: 10.1016/j.scitotenv.2018.05.191. Epub 2018 May 26.
Dry grasslands are listed among the habitats of conservation concern in Europe. Here, based on a multitaxon approach including vascular plants, bryophytes and lichens, we explored the effects of small-scale disturbance on lichen-rich dry grassland vegetation by surveying 60 sites across the Po Plain (Northern Italy). In particular, we evaluated the impact of human trampling and fecal pellet deposition by the alien invasive herbivore Sylvilagus floridanus. We found a soil-dependent response of multiple taxa to the impact of the herbivore. For plants, beside a negative effect of trampling, the interaction between fecal pellet amount and soil pH indicates that the negative effect of the invasive herbivore is stronger on acidic soils. Bryophyte cover increased with increasing soil pH, annual rainfall and fecal pellet, while it was not affected by trampling. Lichen richness and cover decreased with increasing soil pH. The marginal interaction between soil pH and amount of fecal pellet indicates that the more negative effects on lichens may be expected on calcareous soils. Trampling did not affect lichen patterns and the rainfall gradient marginally affected lichen cover with a negative effect. Lichen species richness is also negatively affected by increasing vascular plant cover. The main implications of this study for improving conservation are: (1) conservation practices should be tailored to organism and substrate type; (2) bryophyte and lichen diversity patterns are influenced also by climatic conditions, suggesting that the impact on these organisms may be exacerbated by climate change; and (3) strict conservation, even through active exclusion of wild fauna, of the most species-rich sites should be recommended, even if previous literature and the negative plant cover-lichen richness relationship found in this study indicate that moderate mechanical disturbance could be a practical tool to enhance cryptogams.
干旱草原被列为欧洲关注的保护栖息地之一。在这里，我们基于包括维管植物、苔藓植物和地衣在内的多分类群方法，通过调查意大利北部波河平原的 60 个地点，探索了小规模干扰对富含地衣的干旱草原植被的影响。特别是，我们评估了人类践踏和外来入侵食草动物 Sylvilagus floridanus 的粪便沉积对地衣的影响。我们发现，土壤对地衣和其他多种生物的影响存在依赖关系。对于植物，除了践踏的负面影响外，粪便量与土壤 pH 值之间的相互作用表明，这种入侵食草动物对酸性土壤的负面影响更强。苔藓植物盖度随着土壤 pH 值、年降雨量和粪便量的增加而增加，而不受践踏的影响。地衣丰富度和盖度随土壤 pH 值的增加而降低。土壤 pH 值与粪便量之间的边缘相互作用表明，在钙质土壤上，对地衣的负面影响可能更大。践踏对地衣模式没有影响，而降雨量梯度对地衣盖度的影响较小，呈负相关。地衣物种丰富度也受到维管植物盖度增加的负面影响。本研究对改善保护的主要启示是：（1）保护措施应根据生物和基质类型进行调整；（2）苔藓植物和地衣的多样性模式也受到气候条件的影响，这表明这些生物可能会受到气候变化的影响而加剧；（3）即使在本研究中发现的负面植物盖度-地衣丰富度关系表明适度的机械干扰可能是增强隐花植物的实用工具，也应推荐对物种最丰富的地点进行严格保护，甚至通过主动排除野生动物。
