Abstract Benthic macroinvertebrate functional feeding groups (FFGs) are influenced by the availability of food sources, which can be affected by stream size and gradient. We investigated the spatial distribution patterns of FFGs by stream size (stream order, catchment area and stream width) and gradient (altitude and slope). In addition, we attempted stream classification based on the distribution patterns of FFGs. To achieve these goals, a total of 996 sampling sites of national scale located in the Republic of Korea were investigated from 2008 to 2016. Among the five physical variables, stream width and slope showed linear relationships with the indicator values of FFGs. These two physical variables had larger influences on the distribution of FFGs compared to other variables. Geology (the type of rocks) showed little influences on the distribution of benthic macroinvertebrate communities. We classified streams focusing on catchment (stream size) area and altitude (stream gradient) because they are constants that do not change with disturbances. The FFGs and benthic macroinvertebrate assemblages were distinctly changed by stream types, indicating that the stream classification criterion adequately represented changes in physical variables in biotic terms. In addition, the distribution of FFGs and biotic assemblages showed that benthic macroinvertebrates in the Republic of Korea were more influenced by the altitude (stream gradient) than the catchment area (stream size). In overall, this study found that the stream size and gradient markedly influence the distribution of FFGs in national regions of the Republic of Korea. Further research is needed focusing on the level of microhabitats and other parameters to identify the promising variables that influence biotic distribution.

中文翻译：

---

大韩民国底栖大型无脊椎动物功能性摄食群按河流大小和梯度的空间分布格局

摘要 底栖大型无脊椎动物功能性摄食群 (FFGs) 受食物来源的影响，可受河流大小和梯度的影响。我们通过河流大小（河流顺序、集水区和河流宽度）和梯度（高度和坡度）研究了 FFG 的空间分布模式。此外，我们尝试基于 FFG 的分布模式进行流分类。为实现这些目标，2008 年至 2016 年共调查了位于大韩民国的 996 个国家级采样点。在 5 个物理变量中，河流宽度和坡度与 FFG 的指标值呈线性关系。与其他变量相比，这两个物理变量对 FFG 的分布有更大的影响。地质（岩石类型）对底栖大型无脊椎动物群落的分布几乎没有影响。我们根据集水区（河流大小）面积和海拔高度（河流梯度）对河流进行分类，因为它们是不随干扰而变化的常数。FFG 和底栖大型无脊椎动物组合因河流类型而明显改变，表明河流分类标准充分代表了生物物理变量的变化。此外，FFGs 和生物组合的分布表明，与集水区（河流大小）相比，韩国的底栖大型无脊椎动物受海拔（河流梯度）的影响更大。总体而言，本研究发现河流大小和梯度显着影响大韩民国国家地区 FFG 的分布。