Trends in the recovery of a rosy marsh moth Coenophila subrosea (Lepidoptera, Noctuidae) population in response to fire and conservation management on a lowland raised mire

Abstract

Following a severe fire in 1986 on the estuarine raised mire of Cors Fochno, Wales, a larval transect was initiated across the burnt and unburnt sections to investigate the recovery of the rosy marsh moth Coenophila subrosea population. This paper reports the results of 16 years of surveillance and relates larval density to the growth of the main food plant, bog myrtle Myrica gale. Earlier suggestions that fire is a necessary management tool to maintain Myrica at a young stage of its growth appear unfounded and hydrological effects are probably sufficient to ensure rapid turnover of the foodplant. Eighteen years in which there has been no significant disturbance to the mire vegetation has not led to the predicted decline in the moth population. However, changes in vegetational composition are occurring as a result of conservation management to the hydrological regime of the mire and further studies will be required to investigate whether restoration of the peatland water table leads to a significant reduction in the abundance in food plants or a decline in the status of the rosy marsh moth.