ABSTRACT

Introduction.

Pseudanomodon attenuatus, previously known as Anomodon attenuatus Hedw., is very rare in Britain. In this study, its population status and ecology in England were investigated.

Methods.

Located along the River Eden, Cumbria, the three previously known sites for the species in England were surveyed, plus three potential sites along the river. Abundance was evaluated in terms of ‘individual-equivalents’, each defined as an occupied 1 m grid cell, when the moss was growing on rock, or an occupied tree, when it was epiphytic. Geographical coordinates of each individual-equivalent were recorded with a GPS unit. Habitat and community composition were recorded by relevés.

Results and conclusions.

The species was found at each previously known site and a new site. A total of 127 individual-equivalents were found, and the actual total along the 10.4 km of riverbank surveyed was estimated to be 140–200 individual-equivalents. Along the whole River Eden may be as many as 250–1000 individual-equivalents, because significant amounts of potential habitat remain unsurveyed. The population is confined to the middle to upper inundation zone of the riverbank. About half of individual-equivalents occur on trees and about half on calcareous sandstone. Most trees are Alnus glutinosa; others include Acer pseudoplatanus, Betula pendula, Corylus avellana, Fraxinus excelsior, Quercus robur and Ulmus glabra. Common associates are Anomodon viticulosus, Didymodon insulanus, Homalia trichomanoides and Thamnobryum alopecurum. Reasons for the extreme rarity of P. attenuatus in Britain are uncertain and deserve investigation, as does its confinement to a narrow riparian niche, which appears untypical of P. attenuatus across most of its world range.

中文翻译：

---

英国 Pseudanomodon attenuatus (Hedw.) Ignatov & Fedosov 的种群状况和生态学

摘要

介绍。

Pseudanomodon attenuatus，以前称为Anomodon attenuatus Hedw.，在英国非常罕见。在这项研究中，调查了它在英格兰的种群状况和生态。

方法。

位于坎布里亚郡的伊甸河沿岸，调查了英格兰该物种的三个先前已知地点，以及沿河的三个潜在地点。丰度是根据“个体当量”来评估的，当苔藓生长在岩石上时，每个定义为一个占用的 1 米网格单元，或者当它附生时，它被定义为一棵占用的树。每个等同个体的地理坐标都用 GPS 装置记录。栖息地和社区组成由 relevés 记录。

结果和结论。

该物种是在每个先前已知的地点和一个新地点发现的。总共发现了 127 个个体当量，在所调查的 10.4 公里河岸上的实际总数估计为 140-200 个个体当量。沿着整个伊甸河可能有多达 250-1000 个个体当量，因为仍有大量潜在栖息地未被调查。人口被限制在河岸的中上游淹没区。大约一半的个体当量出现在树上，大约一半出现在钙质砂岩上。大多数树木是Alnus glutinosa；其他包括Acer pseudoplatanus、Betula pendula、Corylus avellana、Fraxinus excelsior、Quercus robur和光榆。常见的伙伴是Anomodon viticulosus、Didymodon insulanus、Homalia trichomanoides和Thamnobryum alopecurum。在英国， P. attenuatus极其稀有的原因尚不确定，值得研究，因为它被限制在狭窄的河岸生态位，这在其世界大部分地区似乎都不是典型的P. attenuatus 。