HABITAT FRAGMENTATION AND THE ABUNDANCES OF VERTEBRATES IN THE FLORIDA SCRUB
HABITAT FRAGMENTATION AND THE ABUNDANCES OF VERTEBRATES IN THE FLORIDA SCRUB
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佛罗里达灌木丛中栖息地的破碎化和脊椎动物的丰富度
DOI：
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发表时间：
1999
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影响因子：
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通讯作者：
H. Mushinsky
中科院分区：
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作者：
E. McCoy;H. Mushinsky
基于存在/不存在的物种，我们以前提出，大片段的佛罗里达砂松灌丛栖息地不具有更大的保护价值的脊椎动物比群岛的小型和中型的片段。我们重新检查了不同大小的碎片的价值，这次是基于物种的丰度。我们询问丰度是否倾向于随着灌木丛大小的减小而减小，或者与其他灌木丛属性更密切相关。我们普查脊椎动物与陷阱阵列和直接观察，我们测量了13个潜在的重要的环境属性相关的区域，隔离，和栖息地结构分布在16灌木沿着佛罗里达州中部的威尔士湖脊。我们将物种的丰富度与13个属性进行了相关分析.我们计算了相对多度分布的均匀度，并根据相对多度分布的形状对灌木进行了分组。我们确定不同的擦洗组的成员是否具有任何属性的不同值。最后，我们研究了大，中，小灌木丛中的个体密度和物种的分散。丰度与许多属性有关。18种植物中有11种的丰度与面积呈正相关。面积解释的变化的百分比一般是低的，几个稀有物种显然保持相对较大的人口在小灌木丛。五种物种的丰度呈负相关的隔离措施。三个物种的丰度呈正相关和负相关的栖息地结构的措施。与隔离和栖息地结构相关的环境属性与均匀度和相对丰度分布的分组相关性最强。个体的总密度（即，每个捕获器阵列的捕获数量）不能显示在不同尺寸的擦洗物之间不同。个体而言，在相对较小的灌木丛中达到最高密度的物种通常被认为是稀有的。物种的空间分布往往变得更加均匀，面积减少，但这种影响的强度不同的物种，也许占，至少部分，为不同的物种之间的丰度和面积之间的关系。我们的研究结果可能会导致广泛的概括，似乎与擦洗相关。例如，由于大多数物种在大型灌木丛中相对丰富，因此应选择大型灌木丛作为保护区，而不是小型灌木丛。然而，我们建议，我们的研究结果实际上最好作为一个警告使用的概括，从一个或几个物种的数据的基础上，一般的保护规划。我们的研究结果清楚地表明，专注于保护较大的灌木碎片对某些物种的好处可能会被对其他物种，特别是稀有物种的伤害所抵消。因此，我们的结论是，选择一个系统的灌木保护区应在很大程度上，尽可能多的居民生物的生物学知识。然而，我们建议，任何储备选择程序的灌木栖息地可能是过时的，生态学家甚至不应该参与辩论的小灌木碎片的保护价值。当一个栖息地像灌木丛一样急剧下降，真正大的剩余碎片充其量是极其罕见的，那么较小的碎片可能具有相当大的价值，无论它们与较大的碎片相比如何。
Based on presence/absence of species, we proposed previously that large fragments of the Florida sand pine scrub habitat do not possess greater conservation value for vertebrates than do archipelagos of small and medium-sized fragments. We reexamined the values of fragments of different sizes, based this time on abundances of species. We asked whether abundances tend to decrease with decreasing scrub size or are more strongly related to other scrub attribute(s). We censused vertebrates with trap arrays and by direct observation, and we measured 13 potentially important environmental attributes related to area, isolation, and habitat structure in 16 scrubs distributed along the Lake Wales Ridge of central Florida. We cor- related abundance of species with the 13 attributes. We calculated the evenness of relative abundance distributions and grouped scrubs based on the shapes of relative abundance distributions. We determined whether or not members of different groups of scrubs pos- sessed different values for any attribute. Finally, we examined both densities of individuals and dispersions of species among large, medium, and small scrubs. Abundance was related to many of the attributes. Abundances of 11 of 18 species were correlated positively with area. Percentage of variation explained by area generally was low, and several of the rare species apparently maintain relatively large populations in small scrubs. Abundances of five species were correlated negatively with measures of isolation. Abundances of three species were correlated both positively and negatively with measures of habitat structure. Environmental attributes related to isolation and habitat structure were correlated most strongly with both evenness and groupings of relative abun- dance distributions. Total density of individuals (i.e., numbers of captures per trap array) could not be shown to differ among scrubs of different sizes. Individually, the species that reached their highest densities in relatively small scrubs often were the ones considered to be rare. Spatial distributions of species tended to become more homogeneous as area decreased, but the strength of this effect varied among species, perhaps accounting, at least in part, for the different relationships between abundance and area among species. Our results could lead to broad generalizations that seem to be relevant to scrub con- servation. For example, because most species are relatively abundant in large scrubs, large scrubs should be selected for reserves over small ones. We suggest, however, that our results actually best serve as a caution about the use of generalizations, based on data from one or a few species, for conservation planning in general. Our results clearly show that the benefits gained for certain species from focusing on the preservation of larger scrub frag- ments could be offset by harm done to other species, especially rare species. We conclude, therefore, that selection of a system of scrub reserves should be based, in large part, on knowledge of the biologies of as many of the resident organisms as possible. We suggest, however, that any reserve selection procedure for the scrub habitat probably is outmoded, and that ecologists should not even engage in debate about the conservation value of small scrub fragments. When a habitat has declined as precipitously as scrub has, and truly large remaining fragments are, at best, extremely rare, then smaller fragments are likely to be of considerable value, no matter how they compare to larger fragments.