Bowers Michael A, Matter Stephen F, Dooley James L, Dauten Jennifer L, Simkins John A
Department of Environmental Sciences and Blandy Experimental Farm, University of Virginia, P.O. Box 175, 22620, Boyce, VA, USA.
Oecologia. 1996 Oct;108(1):182-191. doi: 10.1007/BF00333230.
Habitat fragmentation involves a reduction in the effective area available to a population and the imposition of hard patch edges. Studies seeking to measure effects of habitat fragmentation have compared populations in fragments of different size to estimate and area effect but few have examined the effect of converting open populations to closed ones (an effect of edges). To do so requires a shift in spatial scope-from comparison of individual fragments to that of fragmented versus unfragmented landscapes. Here we note that large-scale, "controlled" studies of habitat fragmentation have rarely been performed and are needed. In making our case we develop a simple computer simulation model based on how individual animals with home ranges are affected by the imposition of habitat edges, and use it to predict population-level responses to habitat fragmentation. We then compare predictions of the model with results from a field experiment on Peromyscus and Microtus. Our model treats the case where home ranges/territories fall entirely within or partially overlap with that of sample areas in continuous landscapes, but are restricted to areas within habitat fragments in impacted landscapes. Results of the simulations demonstrate that the imposition of hard edges can produce different population abundances for similar-sized areas in continuous and fragmented landscapes. This edge effect is disproportionately greater in small than large fragments and for species with larger than smaller home ranges. These predictions were generally supported by our field experiment. We argue that large-scale studies of habitat fragmentation are sorely needed, and that control-experiment contrasts of fragmented and unfragmented microlandscapes provide a logical starting point.
栖息地破碎化涉及到可供种群利用的有效面积减少以及硬边界的形成。旨在衡量栖息地破碎化影响的研究通过比较不同大小碎片中的种群来估计面积效应，但很少有研究考察将开放种群转变为封闭种群的影响（边界效应）。要做到这一点需要转变空间范围——从比较单个碎片到比较破碎景观与未破碎景观。在此我们指出，大规模的、“可控”的栖息地破碎化研究很少进行，且很有必要开展。在阐述我们的观点时，我们基于具有活动范围的个体动物如何受到栖息地边界形成的影响，开发了一个简单的计算机模拟模型，并利用它来预测种群水平对栖息地破碎化的反应。然后我们将模型的预测结果与对鹿鼠和田鼠进行的野外实验结果进行比较。我们的模型考虑了活动范围/领地完全位于连续景观中的采样区域内或部分与之重叠，但在受影响景观中被限制在栖息地碎片内的区域这种情况。模拟结果表明，硬边界的形成会在连续景观和破碎景观中对类似大小的区域产生不同的种群丰度。这种边界效应在小碎片中比在大碎片中更为显著，对于活动范围大的物种比活动范围小的物种更为明显。这些预测总体上得到了我们野外实验的支持。我们认为非常需要开展大规模的栖息地破碎化研究，并且对破碎和未破碎微观景观进行对照实验对比是一个合理的起点。
