Department of Environmental Sciences, Section of Conservation Biology, University of Basel, St. Johanns-Vorstadt 10, Basel, Switzerland.
Environ Manage. 2011 Nov;48(5):1024-32. doi: 10.1007/s00267-011-9727-z. Epub 2011 Aug 24.
Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances. Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed forest areas, is essential for restoration success.
中欧的暴露石灰岩悬崖拥有高度多样化的植物群，其中有许多稀有和濒危物种。在过去几十年中，这些悬崖的休闲使用越来越多，这导致了当地环境的干扰。成功的恢复策略取决于确定关键限制因素。我们研究了在瑞士西北部汝拉山脉受人类践踏严重干扰的混合落叶林的四座石灰岩悬崖底部和四座未受干扰的悬崖底部的地上森林植被组成、土壤种子库中的密度和种子物种组成。我们发现，长期的人类践踏减少了悬崖底部的总地上植被覆盖，并导致植物物种组成发生了显著变化。与未受干扰的悬崖相比，受干扰的悬崖中的总种子密度较低。人类践踏还改变了土壤种子库中种子的物种组成。意外引入的、耐受压力的和先锋物种的种子在受干扰悬崖底部的土壤种子库中占主导地位。我们的研究结果表明，从现有土壤种子库中恢复退化的悬崖底部将导致原始独特植物组成的重大变化。积极的种子转移，或来自相邻未受干扰森林地区的种子流，对于恢复成功至关重要。
