Does the restoration of shallow marginal peatlands impact on the distribution and abundance of Bog Asphodel?

Abstract

Healthy functional peatlands sequester carbon and are therefore important in the mitigation of climate change. In the United Kingdom 80% of peatland has been damaged by anthropogenic activities such as drainage and peat cutting. Most of the degraded peat is globally rare blanket bog found in upland regions, where the principal land use is livestock grazing. Bog asphodel is a common British wildflower found on blanket bog and other very wet peatland habitats, which can also be fatally poisonous to grazing herbivores especially youngstock. Any increase could compromise the grazing in an already difficult environment. This thesis investigated the growth and distribution of bog asphodel on shallow marginal restored peatlands on Exmoor in south-western United Kingdom, both in the field and from a vegetation survey database spanning 11 years from pre-restoration to present at 40 restored sites. The aims were to describe bog asphodel’s phenology, and to assess its life history strategy and its contribution to sward quality in post-restoration habitats. Bog asphodel’s life history strategy is one of tolerating stress, rather than growing quickly or producing large numbers of seeds. This predicts that it will not respond rapidly to peatland restoration. On Exmoor, this prediction is confirmed by the historic data which show bog asphodel growing only slowly after restoration, and not spreading to other restored sites. Bog asphodel can contribute up to 20% of forage value in the transitional bog habitats that develop after rewetting, both in spring and autumn. The implication for the restoration of shallow marginal peatlands is that bog asphodel persists post restoration but does not spread beyond pre-restoration patches or to other sites. Although it can contribute substantially to forage value in rewetted areas no significant injurious effects have been reported, either because more palatable and accessible grazing is available or because bog asphodel itself is less toxic on account of specific environmental conditions.