When to quit? Estimating spider species richness in a northern European deciduous forest
When to quit? Estimating spider species richness in a northern European deciduous forest
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DOI：
10.1636/0161-8202(2003)031
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发表时间：
2003-01-01
影响因子：
1
通讯作者：
Bjorn, PD
中科院分区：
文献类型：
--
作者：
Scharff, N;Coddington, JA;Bjorn, PD
陆地节肢动物调查和清查经常受到抽样不足的偏见；常见物种的代表性过高，稀有物种可能完全被遗漏。这项研究比较了丹麦赫斯特海文一公顷成熟山毛榉森林(Fagus Sylvaticus)中蜘蛛的快速(3天)和密集的清查，其中包括66个物种的8,710只成年蜘蛛，与之前从同一地点进行的为期两年的更全面的两周一次调查，该调查包括141个物种的42,273只(成年和幼年)蜘蛛。非参数物种丰富度估计器被用来评估不同数据分区中欠采样偏差的程度。目前的研究使用了五个有经验的收藏家，四个新手，和五个半定量的收集方法。方法和时间对每个样本的物种和成虫数量有很大影响。采集者的经验影响每个样本的物种数量，但不影响成虫数量。尽管进行了密集的收集，每个样本的成虫数量在研究过程中并没有减少。在采样结束时，样品中仍有31种稀有物种(单胞胎或双胞胎)。非参数丰富度估计器表明，在一年中的这个时候，研究小区中成年蜘蛛的实际丰富度约为80种，对所用方法的影响很大。两次调查(长达23年)之间的物种周转量非常小：两份名单92%相同。基线研究表明，在31个稀有物种中，有12个物种的稀有性是人为的(10个是物候原因，一个是方法原因，另一个是空间边缘效应)。余数的稀有性无法解释，默认情况下被解释为欠采样偏差。
Terrestrial arthropod surveys and inventories frequently suffer from undersampling bias; common species are over-represented and rare species may be missed entirely. This study compared a rapid (3 days) and intense inventory of spiders from one hectare of a mature beech forest (Fagus sylvaticus) in Hestehaven, Denmark, comprising 8,710 adult spiders of 66 species to a previous, much more thorough, bi-weekly survey of two years duration from the same site that comprised 42,273 spiders (adult and juvenile) of 141 species. Non-parametric species richness estimators were used to assess the degree of undersampling bias in various data partitions. The current study used five experienced, four novice collectors, and five semi-quantitative collecting methods. Method and time of day strongly affected numbers of species and adults per sample. Collector experience affected numbers of species but not numbers of adults per sample. Despite the intensive collecting, number of adults per sample did not decrease over the course of the study. At the end of the sampling, 31 species were still rare in the sample (singletons or doubletons). Non-parametric richness estimators suggest that the actual richness of adult spiders in the study plot at this time of year and susceptible to the methods used was about 80 species. Species turnover between the two surveys (ca 23 years) was remarkably small: the two lists were 92% identical. The baseline study suggests that the rarity of 12 of the 31 rare species was artifactual (10 due to phenology, one to method, another to spatial edge effects). The rarity of the remainder is unexplained and by default is interpreted as undersampling bias.