Using Fractals to Describe Ecologically Relevant Patterns in Distributions of Large Rocks in Streams
Using Fractals to Describe Ecologically Relevant Patterns in Distributions of Large Rocks in Streams
复制标题
DOI：
10.1029/2021wr029796
复制
发表时间：
2021-07
影响因子：
5.4
通讯作者：
Georgia K. Dwyer;C. Cummings;Stephen P. Rice;J. Lancaster;B. Downes;Louise J. Slater;R. Lester
中科院分区：
文献类型：
--
作者：
Georgia K. Dwyer;C. Cummings;Stephen P. Rice;J. Lancaster;B. Downes;Louise J. Slater;R. Lester
测量栖息地或生态资源的物理复杂性通常是使用特定于系统的方法来实现的，这使得跨生态系统的比较变得困难。分形维数是适用于多个生态系统和尺度的一种衡量标准，它具有通用性和潜在的尺度独立性的优点。这项研究评估了使用盒子计数和熵分形维数来表征苏格兰和澳大利亚六条溪流中突现岩石分布的复杂性。挺水岩（ER）是重要的水力特征和生态资源，包括作为水生昆虫的产卵地和鱼类的覆盖物。我们完成了对沿 6 条河流纵向延伸的 5 米段内 ER 计数的分形分析。所有六个流都表现出分形行为（自相似性），表明分形可用于以与尺度无关的方式测量纵向 ER 分布的复杂性。熵是一种优越的测量方法，因为它能够区分六个流，而盒计数则不能。现场结果和数值模拟共同表明，突出岩石分布的分形维数与河流地貌有关。发育良好的河床形态，如交替的水池和浅谷，具有更好组织的突现岩石，因为大的河床物质更有可能在地形高处出现。河床物质较粗的溪流中，突出岩石的排列更加混乱，因为这增加了突出岩石的总体丰度，使得地形高点和低点之间的差异不那么明显。因此，分形维数可以通过与地貌和生态过程相关的方式来衡量河流系统的复杂性。
Measuring the physical complexity of habitats or ecological resources is often achieved using system‐specific methods that make comparisons across ecosystems difficult. One measure that is applicable across multiple ecosystems and scales is the fractal dimension, which has the benefit of generality as well as potential scale independence. This study evaluated the use of box‐counting and entropy fractal dimensions for characterizing the complexity of emergent rock distributions in six streams across Scotland and Australia. Emergent rocks (ER) are important hydraulic features and ecological resources, including as oviposition sites for aquatic insects and cover for fish. We completed fractal analysis on counts of ER in 5‐m segments along longitudinal stretches of the six streams. All six streams exhibited fractal behavior (self‐similarity), suggesting that fractals can be used to measure the complexity of longitudinal ER distributions in a way that is scale independent. Entropy was a superior measure due to its ability to differentiate among the six streams whereas box‐counting could not. Together, field results and numerical simulations showed that fractal dimensions of emergent rock distributions were related to stream geomorphology. Well‐developed bedforms, like alternating pools and riffles had better organized emergent rocks because large bed materials were more likely to be emergent in topographic highs. Streams with coarser bed materials had more chaotic arrangements of emergent rocks because this increased the general abundance of emergent rocks, making differentiation between topographic highs and lows less distinctive. Fractal dimensions, therefore, can measure the complexity of river systems in a way that is relevant to geomorphological and ecological processes.