The role of livestock grazing in the conservation of lowland heath

Domestic livestock grazing is increasingly used as a conservation tool on lowland heaths. However, the impacts of livestock on vegetation and the implications of their behaviour are not fully understood. This study considered habitat selection and behaviour in seven livestock groups on lowland heaths in Dorset, southern England. The impact of livestock on wet heath and valley mire vegetation was assessed experimentally. The potential role of livestock grazing and trampling in the germination of eight characteristic wet heath and valley mire plant species was established, and the potential for livestock-facilitated regeneration from buried seed banks was explored. Livestock showed non-random use of habitats, and generally preferentially selected habitats with a high cover of grass species. Use of dry heath varied according to the age and structure of heather Calluna vuglaris. There was seasonal variation in habitat selection, notably the increased use of wet heath and valley mire in late summer. However, foraging was not the only activity dictating habitat selection, and selection for resting locations also influenced overall habitat use. Livestock grazing and trampling had a significant impact on vegetation structure and the cover of bare ground within three years. The impact on substrate microtopography, compaction and standing water was also significant. Changes in species composition were more subtle, and may take longer than three years to become apparent. The emergence of selected wet heath and valley mire species was shown to be increased by simulated livestock trampling. Higher water levels increased emergence, but reduced canopy shading was not important in most species studied. Habitat surveys suggest that canopy shading may be important in the subsequent establishment and survival of these spices. Livestock trampling also has the potential to increase species emergence through exposure of buried seed banks. This was shown to result in species regeneration at sties where they were considered extinct in the above ground vegetation.