The distribution, density and cover of small-scale natural disturbances was surveyed in semi-natural and set-aside vegetation in a hilly landscape in Central Germany in the spring of 1995. More of the landscape was disturbed on set-aside agricultural land in valleys (1.02 %) and on warm south-facing slopes (1.33 %) than on rocky hilltops (0.3 %) and cool north-facing slopes (0.56 %). The major agents of disturbance on set-aside fields were moles, rodents (and their predators) and wild boars. In surrounding semi-natural grasslands, rabbit warrens were common on south-facing slopes and mound-building ants on north-facing slopes. Disturbances were sig-nificantly clustered and frequently superimposed. In order to investigate the effects of disturbance quality on plant assemblages in set-aside fields, two common types of disturbances were compared. These were grazing lawns (0.4 -1.0 m 2) maintained throughout the summer by common voles (Microtus arvalis), and excavations, 0.7 -1.6 m 2 in area, where wild boars (Sus scrofa) grubbing for food had removed veg-etation and top soil in early spring. Both types of disturbances increased plant species richness on the local scale. Wind-dispersed annual and pauciennial forbs of ruderal habitats (e.g. Carduus acanthoides, Cirsium vulgare, Matricaria maritima, Senecio vernalis) were most abundant on the superficial dis-turbances made by voles, whereas small, ephemeral field weeds (e.g. Polygonum aviculare, Anagallis arvensis, Cheno-podium album, Fallopia convolvulus) predominated on patches grubbed by boars. This study confirms that small-scale disturbances by ani-mals provide a variety of regeneration niches for field weeds and ruderals. The rate of decline in plant species richness on set-aside land is likely to be reduced where land is utilized by a variety of herbivorous and soil-moving mammals.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below