Geographical separation of two Ulex species at three spatial scales:: does competition limit species' ranges?
Geographical separation of two Ulex species at three spatial scales:: does competition limit species' ranges?
复制标题
DOI：
10.1111/j.1600-0587.2000.tb00281.x
复制
发表时间：
2000-04-01
期刊：
影响因子：
5.9
通讯作者：
Rose, RJ
中科院分区：
文献类型：
--
作者：
Bullock, JM;Edwards, RJ;Rose, RJ
人们普遍认为，物种的活动范围受到其对气候因素的生理耐受性的限制。很少考虑竞争等生物因素。我们调查了 Ulexminor 和 U. gallii 在三个空间尺度上的分布——从地理范围到个体石南——以检查这些物种是否负相关，正如物种范围受到相互竞争限制的假设所预测的那样。不列颠群岛和法国的分布图（100-400 km(2) 调查单位）显示，这两个物种的分布范围基本分开，但略有重叠。使用 4 公顷的测量方格绘制了英格兰南部多塞特荒地上的一个范围重叠区域。物种之间存在很强的负相关性，石南地可以分为一个物种占优势的区域。有一些迹象表明，小 U. 主导区和 U. gallii 区之间的土壤差异。使用沿横断面放置的 4 m(2) 样方对物种共存的少数石南地进行了调查。通常，一种物种广泛分布在荒原上，而另一种则成片出现。该物种在所有样带中均呈强烈负相关。因此，这两个物种在三个绘图尺度上表现出强烈的负关联。当物种以更精细的尺度绘制时，在一个空间尺度上检测到的明显共现很大程度上消失了，强调了分布的分形性质。这证明这两个物种的分布不是独立的，它们不能共存，因此它们的范围受到竞争的限制。在它们的分布范围内，竞争优势可能是由气候决定的。在重叠区域的范围边界，气候并不重要，但土壤条件等其他物理因素可能会决定竞争的结果。
It is a common assumption that species' ranges are limited by their physiological tolerances to climatic factors. Biotic factors, such as competition, are rarely considered. We investigated the distributions of Ulex minor and U. gallii at three spatial scales - from geographic ranges to individual heaths - to examine whether the species are negatively associated, as predicted by the hypothesis that the ranges of the species are limited by competition with each other. Distribution maps for the British Isles and France (100-400 km(2) survey units) show the two species have largely separated, but slightly overlapping ranges. A region of range overlap on the heaths of Dorset, southern England was mapped using 4 ha survey squares. There was strong negative association between the species, and the heaths could be divided into zones where one species was dominant. There was some indication of edaphic differences between the U. minor-dominated zones and the U. gallii zones. The few heaths where the species co-occurred were surveyed using 4 m(2) quadrats placed along transects. Usually one species was widespread over the heath, while the other occurred in patches. The species were strongly negatively associated in all transects. Therefore, the two species showed strong negative associations at three mapping scales. Apparent co-occurrences detected at one spatial scale largely disappeared when species were mapped at finer scales, emphasising the fractal nature of distributions. This provides evidence that the distributions of the two species are not independent and that they cannot coexist, and therefore that their ranges are limited by competition. Over their ranges, competitive superiority is probably determined by the climate. At the range boundaries in the region of overlap, climate is not important, but other physical factors such as edaphic conditions may determine the outcome of competition.