Detecting decline in a formerly widespread species: How common is the common blue butterfly Polyommatus icarus?
Detecting decline in a formerly widespread species: How common is the common blue butterfly Polyommatus icarus?
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检测以前广泛分布的物种的衰退：常见的蓝蝴蝶Polyommatus 伊卡洛斯有多常见？
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
C. Thomas
中科院分区：
文献类型：
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作者：
J. León;M. Cowley;C. Thomas
网格方形分布图已被广泛用于测量下降速度和目标保护资源。然而，每个方格中可能有许多种群的普通物种可以从方格内大量减少，而不会从整个方格中消失。为了量化这一过程，在威尔士北部一个35平方公里的破碎景观区域内，收集了常见蓝蝴蝶（Polyommatus icarus）的细尺度种群和栖息地数据。根据2000多个样带步行的数据，结合历史和现在的栖息地分布数据显示，自1901年以来，该物种已经减少了约74%，其主要寄主植物莲花的类似数据显示下降了46%。根据1平方公里的网格图，这两个物种都没有被评估为正在下降。这些结果表明，表面上常见的物种可能和英国的许多稀有物种一样减少了：使用目前的评估方法，这些减少是未被发现的。
Grid square distribution maps have been used widely to measure rates of decline and target conservation resources. However, common species that may have many populations per grid square can decline substantially from within squares without being lost from entire squares. In order to quantify this process, fine scale population and habitat data have been collected for the common blue butterfly Polyommatus icarus in a 35 km 2 area of fragmented landscape in north Wales. Present day habitat associations, determined from over 2000 transect walks, combined with data on historical and present day habitat distributions reveal that the species has declined by about 74% since 1901, Similar data concerning the species' major host plant Lotus corniculatus indicate a decline of 46%. Based on I km 2 grid maps, neither species have been assessed as declining at all. These results suggest that apparently common' species may have declined just as much as many of Britain's rare species: using present methods of assessment these declines are undetected.