ABSTRACT

Introduction. This study investigated the ecology of Petalophyllum ralfsii in 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 of P. ralfsii were recorded using high-precision GPS. Vegetation was recorded by relevés and hydrology investigated from dipwell data.

Results. Petalophyllum ralfsii was recorded at 1322 locations, mostly along pony trails, but also in sparsely vegetated depressions and restoration scrapes. The most frequent associates were Carex flacca, Didymodon tophaceus, Equisetum variegatum and Ptychostomum 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 × 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 on P. 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 by P. ralfsii, but the population is small, likely related, at least in part, to water availability.

摘要

介绍。本研究调查了海洋沙丘系统中Petalophyllum ralfsii的生态，包括与放牧牲畜、水文和栖息地恢复的关系。

方法。研究地点是位于英国西北部威尔士纽伯勒沃伦的两个大型休闲区。在一片荒凉的地区，有 6 年历史的“恢复刮痕”，植被被剥离以恢复早期的演替栖息地。自 2001 年以来，这两条马甲都进行了持续的保护性放牧，主要是小马。使用高精度 GPS 记录了P. ralfsii 的位置。植被由相关数据记录，并根据浸水井数据进行调查。

结果。Petalophyllum ralfsii被记录在 1322 个地点，主要是沿着小马小径，但也在植被稀疏的洼地和恢复刮痕中。最常见的同伙是Carex flacca、Didymodon tophaceus、Equisetum variegatum和Ptychostomum pseudotriquetrum。在一些冬天，潮湿的地方可能会被长时间淹没。在研究的五个冬天期间，较干燥的地方根本没有洪水。在占用的 5 × 5 m 网格单元内，位置的垂直范围不超过 16 cm。修复刮痕中的位置仅限于地下水位相对较高的区域。

结论。放牧对P. ralfsii产生了重大的积极影响。沿着小马小径践踏提供了竞争性的释放，并且由于更大的土壤容重，延长了地表的可用水量。小马很可能通过在它们的蹄子上运输水铝石来直接分散到合适的微生境中。修复刮痕已被P. ralfsii定殖，但种群很小，可能至少部分与可用水有关。