Department of Environmental Horticulture and Soil, Water, and Ecosystem Sciences Department, University of Florida, Gainesville, FL, 32611, USA; Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, 84322, USA.
Department of Watershed Sciences and Ecology Center, Utah State University, Logan, UT, 84322, USA; Utah Department of Agriculture and Food, Taylorsville, UT, 84129, USA.
J Environ Manage. 2024 Jun;362:121168. doi: 10.1016/j.jenvman.2024.121168. Epub 2024 May 31.
Targeted grazing to control undesirable plant species is increasingly of interest across a diversity of ecosystems, particularly as an alternative or complement to widely used herbicides. However, there are limited comprehensive evaluations of targeted grazing that evaluate both invasive species management effectiveness and potential negative effects on the ecosystem. Phragmites australis, a tall-statured, dense perennial invasive grass from Eurasia, is a pervasive problem in wetlands across the North American continent. As with many invasive species where management has historically relied on herbicides and resistance is a growing concern, land managers seek viable alternatives that have minimal negative ecosystem impacts. Grazing has been used for millennia to manage native Phragmites in Europe. Similarly, in its invasive range within North America, small-scale studies suggest Phragmites may be suppressed by grazers. Yet, the effectiveness of grazing at large scales and its effects on broader ecosystem properties remain largely unknown. We evaluated the influence of targeted grazing on vegetation, soil nutrients, and water nutrients over two years in large plots (∼300x the size of previous studies). We also tested the effects of mowing, a treatment that can be used to facilitate grazer access to large, dense Phragmites stands. In line with our predictions, we found that cattle grazing effectively suppressed invasive Phragmites over two years. Mowing reduced litter, and moderately reduced standing dead Phragmites, both of which suppress native plant germination in this system. However, these reductions in Phragmites were not accompanied by indications of native plant community recovery, as we had optimistically predicted. Despite the potential for grazing to reduce nutrient sequestration by plants and fertilize soils, we were surprised to find no clear negative effects of grazing on nutrient mobilization to groundwater or floodwater. Taken together, our findings indicate that targeted grazing, when implemented at broad scales over short time frames, is effective at achieving invasive plant management goals without sizable nutrient impacts. However, additional steps will be needed to achieve the restoration of diverse, robust native plant communities.
针对特定植物物种的放牧控制策略在各种生态系统中越来越受到关注，尤其是作为广泛使用的除草剂的替代或补充措施。然而，目前针对放牧控制的综合评估有限，这些评估既评估了入侵物种管理的有效性，也评估了其对生态系统的潜在负面影响。来自欧亚大陆的高大、密集多年生入侵性草类——荻，是北美大陆湿地的普遍问题。与许多历史上依赖除草剂管理且抗药性日益成为关注焦点的入侵物种一样，土地管理者寻求对生态系统负面影响最小的可行替代方案。放牧在欧洲已经使用了数千年来管理本地荻。同样，在其入侵北美地区，小规模研究表明，食草动物可能会抑制荻的生长。然而，放牧在大规模应用的有效性及其对更广泛的生态系统特性的影响在很大程度上仍不清楚。我们在两年内，在大样地（是之前研究的 300 倍大小）中评估了针对荻的放牧对植被、土壤养分和水养分的影响。我们还测试了刈割的效果，这是一种可以用来促进食草动物进入大型密集荻种群的处理方法。与我们的预测一致，我们发现牛群放牧在两年内有效地抑制了入侵荻。刈割减少了凋落物，并适度减少了直立死荻，这两者都会抑制本系统中植物的发芽。然而，正如我们乐观预测的那样，荻的这些减少并没有伴随着本地植物群落恢复的迹象。尽管放牧可能会减少植物对养分的吸收并为土壤施肥，但我们惊讶地发现，放牧对地下水或洪水养分的迁移没有明显的负面影响。总的来说，我们的研究结果表明，在短时间内广泛实施有针对性的放牧，可以有效地实现入侵植物管理目标，而不会对养分产生显著影响。然而，需要采取额外的措施来实现多样化、强健的本地植物群落的恢复。
