Pony trails, hydrology and habitat restoration: aspects of the ecology ofPetalophyllum ralfsiiin a Welsh oceanic dune system

Introduction. This study investigated the ecology ofPetalophyllum ralfsiiin an oceanic dune system, including relationships with grazing livestock, hydrology and habitat restoration. Methods. The study site was two large slacks at Newborough Warren, NW Wales, UK. In areas of one slack, there are 6-yr-old 'restoration scrapes', where vegetation was stripped to restore early successional habitat. Since 2001, both slacks have had continuous conservation grazing, primarily by ponies. Locations ofP. ralfsiiwere recorded using high-precision GPS. Vegetation was recorded by releves and hydrology investigated from dipwell data. Results.Petalophyllum ralfsiiwas recorded at 1322 locations, mostly along pony trails, but also in sparsely vegetated depressions and restoration scrapes. The most frequent associates wereCarex flacca, Didymodon tophaceus, Equisetum variegatumandPtychostomum pseudotriquetrum. Wetter locations could be flooded for prolonged periods in some winters. Drier locations did not flood at all during the five winters of the study. Within occupied 5 x 5 m grid cells, vertical range of locations was no more than 16 cm. Locations in restoration scrapes are confined to areas where the water table is relatively high. Conclusions. Livestock grazing had a major positive impact onP. ralfsii. Trampling along pony trails provided competitive release and, due to greater soil bulk density, prolonged water availability at the surface. Ponies likely provided directed dispersal into suitable microhabitats via transport of diaspores on their hooves. Restoration scrapes have been colonised byP. ralfsii, but the population is small, likely related, at least in part, to water availability.

Automated summary

This study investigated the ecology of Petalophyllum ralfsii in an oceanic dune system and found that livestock grazing had a major positive impact on the species. Ponies likely provided directed dispersal into suitable microhabitats. Although restoration scrapes have been colonised by P. ralfsii, the population is small, likely related to water availability.