Effects of Long-Term Trampling on the Above-Ground Forest Vegetation and Soil Seed Bank at the Base of Limestone Cliffs

Abstract

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.

Intensity-dependent impact of sport climbing on vascular plants and land snails on limestone cliffs

“…Clearing 84 of soil from crevices and erosion of the cliff edge and face have also been recorded (McMillan 85 and Larson, 2002;Kuntz and Larson, 2006). Furthermore, human trampling has reduced the 86 above-ground vegetation cover at the base of cliffs and caused significant shifts in plant 87 species composition (Rusterholz et al, 2011). 88…”

“…Not all parts of a cliff might be affected in the same way by sport climbing. At the cliff 97 base (or talus), trampling by climbers and people securing the climbers destroys the ground 98 vegetation, reduces the litter layer and the abundance of invertebrates living in it, and 99 compacts the soil (Rusterholz et al, 2011; Fig. S2).…”

Aboveground Vegetation and Perennial Grass Seed Bank in Arid Rangelands Disturbed by Grazing

“…At bare soil microsites, we found a clear positive relationship between the aboveground plant cover and perennial grass seed attributes (seed density and number of litter patches with seeds), without significant differences in the size and cover of litter patches. This could result from decreasing seed inputs, augmented distances from seed sources, increased seed redistribution by wind or water, and increased trampling at bare soil microsites with decreasing plant cover (Kemp, 1989;Marone et al, 1998;Aguiar & Sala, 1999;Bertiller et al, 2002;Pazos & Bertiller, 2008;DeFalco et al, 2009;Rusterholz et al, 2011). Litter patches at canopy microsites may act as the primary seed sources for neighboring litter patches in bare soil areas, mostly enhancing perennial grass seed density at bare soil at locations with high aboveground vegetation.…”

Population structure and genetic diversity of relict populations of Alyssum montanum on limestone cliffs in the Northern Swiss Jura mountains

“…We therefore suggest that adequate management actions should be developed and implemented to promote A. montanum on cliffs. The action plans should preserve the specialized plants from intensive mechanic disturbances by sport climbing and hiking (McMillan and Larson 2002;Müller et al 2004;Rusterholz et al 2004Rusterholz et al , 2011. Furthermore, an adequate forest management should prevent the rocky cliffs from being shadowed by overgrowing forest (Müller et al 2006).…”