The potential of goats to kill tress and scrub invading calcareous grassland-a case study

摘要

In the UK the condition of the remaining lowland calcareous grassland is often compromised by invasions of woody plant species. Removal of scrub /trees to restore grassland has become a major management activity, especially on small sites. In this paper we describe the degree to which the goat (Capra hircus), a browsing livestock species, attacks and kills tree/scrub species that often invade calcareous grassland. Over one winter, goats were stocked at five per hectare on a chalk grassland which had been invaded by trees and scrub, some of which had developed into woodland. The study site was in the Chilterns (in southern England). In a random sample (N = 135), ten tree/scrub species were recorded, eight of which had been attacked by the goats. Elder (Sambucus nigra) was strongly selected for and within two years all bark-stripped trunks had died. Ash (Fraxinus excelsior) was weakly selected for but the growth of foliage above ring-barked trunks was weak with evidence of dieback. Hawthorn (Crataegus monogyna) was occasionally attacked but largely avoided. Neither buckthorn (Rhamnus catharticus), nor cherry (Prunus avium) was attacked. The goats clearly showed potential to kill several tree/scrub species. However, they would need to present for several winters on the site before removal of woodland and restoration to grassland was successful. In addition, reluctance to attack hawthorn may mean that manual/chemical control of this species is also needed if effective control is to be achieved.