Wellnitz Todd, Barlow Jenna L, Dick Cory M, Shaurette Terrance R, Johnson Brian M, Wesley Troy, Weiher Evan
Biology Department, University of Wisconsin-Eau Claire, Eau Claire, WI, USA.
PeerJ. 2020 Feb 25;8:e8656. doi: 10.7717/peerj.8656. eCollection 2020.
Factors controlling the spread of invasive earthworms in Minnesota's Boundary Waters Canoe Area Wilderness are poorly known. Believed to have been introduced by anglers who use them as bait, invasive earthworms can alter the physical and chemical properties of soil and modify forest plant communities. To examine factors influencing earthworm distribution and abundance, we sampled 38 islands across five lakes to assess the effects of campsites, fire and entry point distance on earthworm density, biomass and species richness. We hypothesized that all three parameters would be greater on islands with campsites, lower on burned islands and would decrease with distance from the wilderness entry point. In addition to sampling earthworms, we collected soil cores to examine soil organic matter and recorded ground and vegetation cover. Campsite presence was the single most important factor affecting sampled earthworm communities; density, biomass and species richness were all higher on islands having campsites. Fire was associated with reduced earthworm density, but had no direct effects on earthworm biomass or species richness. Fire influenced earthworm biomass primarily through its negative relationship to groundcover and through an interaction with entry point distance. Entry point distance itself affected earthworm density and biomass. For islands with campsites, earthworm biomass increased with distance from the entry point.
控制入侵蚯蚓在明尼苏达州边界水域独木舟区域荒野扩散的因素鲜为人知。入侵蚯蚓据信是由将其用作鱼饵的垂钓者引入的，它们会改变土壤的物理和化学性质，并改变森林植物群落。为了研究影响蚯蚓分布和数量的因素，我们在五个湖泊中的38个岛屿上进行了采样，以评估露营地、火灾和距离入口点的距离对蚯蚓密度、生物量和物种丰富度的影响。我们假设这三个参数在有露营地的岛屿上会更高，在被烧毁的岛屿上会更低，并且会随着与荒野入口点距离的增加而降低。除了对蚯蚓进行采样外，我们还采集了土壤芯以检查土壤有机质，并记录了地面和植被覆盖情况。露营地的存在是影响所采样蚯蚓群落的唯一最重要因素；在有露营地的岛屿上，密度、生物量和物种丰富度都更高。火灾与蚯蚓密度降低有关，但对蚯蚓生物量或物种丰富度没有直接影响。火灾主要通过其与地被植物的负相关关系以及与入口点距离的相互作用来影响蚯蚓生物量。入口点距离本身会影响蚯蚓密度和生物量。对于有露营地的岛屿，蚯蚓生物量随着与入口点距离的增加而增加。
