Animal Ecology, Bielefeld University, Konsequenz 45, 33615, Bielefeld, Germany.
BMC Ecol. 2018 Oct 11;18(1):43. doi: 10.1186/s12898-018-0198-4.
Stemflow is an essential hydrologic process shaping the soil of forests by providing a concentrated input of rainwater and solutions. However, the transport of metazoans by stemflow has yet to be investigated. This 8-week study documented the organisms (< 2 mm) present in the stemflow of different tree species. Because the texture of the tree bark is a crucial determination of stemflow, trees with smooth bark (Carpinus betulus and Fagus sylvatica) and rough bark (Quercus robur) were examined.
Up to 1170 individuals per liter of stemflow were collected. For rotifers and nematodes, a highly positive correlation between abundance and stemflow yield was determined. Both taxa were predominant (rotifers: up to 70%, nematodes: up to 13.5%) in the stemflow of smooth-barked trees whereas in that of the oak trees collembolans were the most abundant organisms (77.3%). The mean number of organisms collected per liter of stemflow from the two species of smooth-barked trees was very similar. A higher number of nematode species was found in the stemflow of these trees than in the stemflow of rough-barked oak and all were typical colonizers of soil- and bark-associated habitats.
This pilot study showed for the first time that stemflow is a transport vector for numerous small metazoans. By connecting tree habitats (e.g., bark, moss, lichens or water-filled tree holes) with soil, stemflow may influence the composition of soil fauna by mediating intensive organismal dispersal.
茎流是一种重要的水文过程，通过提供集中的雨水和溶液输入来塑造森林土壤。然而，后生动物通过茎流的运输尚未得到研究。这项为期 8 周的研究记录了不同树种茎流中存在的生物体（<2 毫米）。因为树皮的质地是茎流的一个关键决定因素，所以研究了树皮光滑的树（欧洲山毛榉和欧洲水青冈）和树皮粗糙的树（欧洲栎）。
每升茎流中最多可收集到 1170 个个体。对于轮虫和线虫，确定了丰度与茎流产量之间的高度正相关。这两个类群在光滑树皮树木的茎流中占主导地位（轮虫：高达 70%，线虫：高达 13.5%），而在栎树的茎流中，弹尾目昆虫是最丰富的生物（77.3%）。从两种光滑树皮树木每升茎流中收集到的平均生物数量非常相似。在这些树木的茎流中发现了更多的线虫物种，而在粗糙树皮的栎树的茎流中则发现了所有这些都是土壤和树皮相关栖息地的典型殖民者。
这项初步研究首次表明，茎流是许多小型后生动物的运输载体。通过将树木栖息地（如树皮、苔藓、地衣或充满水的树洞）与土壤连接起来，茎流可能通过介导密集的生物扩散来影响土壤动物群落的组成。
