EFFECT OF SAMPLE SIZE, PLOT SIZE, AND COUNTING TIME ON ESTIMATES OF AVIAN DIVERSITY AND ABUNDANCE IN A CHILEAN RAINFOREST
EFFECT OF SAMPLE SIZE, PLOT SIZE, AND COUNTING TIME ON ESTIMATES OF AVIAN DIVERSITY AND ABUNDANCE IN A CHILEAN RAINFOREST
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样本大小、样地大小和计数时间对智利雨林鸟类多样性和丰富度估计的影响
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
J. Jiménez
中科院分区：
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作者：
J. Jiménez
摘要1993-1994年繁殖季节，对智利南部奇洛埃岛南部温带雨林的鸟类群落进行了研究。采用改进的可变圆形样地法研究了当样地大小、样地持续时间和样地数量发生变化时，对鸟类总密度和物种丰富度估计值的影响。在18个样地上记录了24个物种的459个个体，采样时间最长为10 min，距离不限。当增加地块大小，采样长度或地块数量时，检测到的物种数量以下降的速度增加，但没有达到渐近线。估计密度随样地大小的增加而减小，随取样长度的增加而增加，并不随样地数量的增加而变化。然而，精度大大提高。在半径为40米的地块上，计数10分钟，可检测到78%的较大地块中发现的物种，总体鸟类密度为34只/公顷，几乎是唯一可比研究发现的两倍。平均而言，在5个地块上，使用4分钟的采样时间，超过75%的所有物种都在观察者的40米范围内。最丰富的物种是迁徙杂食性的捕蝇草Elaenia albiceps（占总数的22%），其次是蜂鸟Sephanoides galeritus，Tapaculo Scelorchilus rubecola，树鼩 Aphrastura spinicauda和长尾鹦鹉Enicognathus ferrugineus。这些物种，这是在类似的温带南美森林进行的其他研究中最常见的，表现出物种特异性的响应采样变量的变化。
Abstract The bird assemblage of a southern temperate rainforest on Chiloé Island, southern Chile, was studied during the breeding season of 1993–1994. The modified variable-circular plot method was used to examine the effects on the estimated overall density and species richness of birds when the size of the plot, duration at the plot, and number of plots were varied, one variable at a time. A total of 459 individuals of 24 species was recorded on 18 plots sampled for a maximum of 10 min with unlimited distance. When increasing either the plot size, sampling length, or number of plots, the number of species detected increased at a decreasing rate, but without reaching an asymptote. The estimated density decreased with increasing plot size, increased with sampling length, and did not change with increasing plot number. However, the precision substantially improved. Plots of 40-m radius counted for 10 min detected 78% of the species found in larger plots and rendered an overall bird density of 34 individuals/ha, almost twice as many as the only comparable study found. On average, more than 75% of all species detected were within 40 m of the observers, using a 4-min sampling period at five plots. The migrant omnivorous flycatcher Elaenia albiceps was the most abundant species (22% of total counts), followed by the hummingbird Sephanoides galeritus, the tapaculo Scelorchilus rubecola, the treecreeper Aphrastura spinicauda, and the parakeet Enicognathus ferrugineus. These species, which were the most common in other studies conducted in similar temperate South American forests, showed species-specific responses to changes in the sampling variables.