Data from: Evaluation of mowing frequency on right-of-way plant communities in Mississippi

Abstract: Native grasses and native wildflowers are declining, especially along roadside right-of-ways due to intensive mowing and herbicide management practices. Roadside right-of-ways undergo regular disturbances such as mowing, maintenance, and road developments that affect soils, groundwater, surface hydrology, and vegetation composition. We investigated species richness and percent coverage within plant communities along highway right-of-ways to determine if reduced mowing increased native plant coverage. The study was conducted using 10 research plots situated along Highway 25 in Oktibbeha and Winston counties, Mississippi. Each research plots consisted of three different treatments as follows: one that included greater than four mowings per year, one mowing only in fall, and one mowing only in fall with a supplemental native wildflower seeding. Using line transect sampling, we detected 277 plant species, which included native and non-native forbs, legumes, grasses, rushes, sedges, and woody perennials (vines, shrubs, and trees). Total percent coverage of native and non-native plants within different growth form categories did not differ among treatments (F2, 96 = 0.45, P = 0.83). However, coverage differed between uplands and lowlands (F1, 96 = 18.22, P {less than or equal to} 0.001), between years (F1, 96 = 14.54, P {less than or equal to} 0.001), between fall and spring seasons (F1, 96 = 16.25, P {less than or equal to} 0.001), and interacted between years and seasons (F1, 96 = 24.08, P {less than or equal to} 0.001) and seasons and elevations (F1, 96 = 5.00, P {less than or equal to} 0.001). Non-native agronomic grasses exhibited the greatest coverage ({greater than or equal to}90%) in all treatments. Percent coverage of each plant growth form was greatest in lowlands. Our research showed an increase of native grasses and wildflower species along roadsides with a reduced mowing regimen. We concluded that the timing and intensity of mowing for the duration of our study had little effect on the species composition of plant communities. However, one mowing per year retained agronomic plant coverage for erosion control and soil stabilization during roadside maintenance. Specific proactive management implementations can include native plantings, selective herbicide use to decrease non-native grasses, continual mowing from roadside edge to 10 meters (m), and only one mowing in late fall, but with an extension of the boundary to reach beyond 10 m from the roadside edge to suppress the invasion of woody plants, which could lead to lower long-term maintenance costs.

摘要：本土草本植物与本土野生花卉正面临种群衰退，在因高频刈割与除草剂施用管理而受到干扰的公路路域区域中，这一现象尤为显著。公路路域区域会频繁经历各类扰动，包括刈割、道路维护与道路开发等活动，这些扰动会对土壤、地下水、地表水文状况以及植被群落组成造成影响。本研究针对公路路域内的植物群落展开调查，分析其物种丰富度与百分盖度，旨在探究降低刈割频率是否能够提升本土植物的盖度。本研究于美国密西西比州奥克蒂比哈县与温斯顿县的25号高速公路沿线开展，共设置10个研究样地。每个样地均设置3种不同的刈割处理方案：其一为年刈割次数多于4次；其二仅在秋季进行1次刈割；其三为仅在秋季刈割并辅以本土野生花卉补播。本研究采用样线抽样法开展调查，共记录到277种植物，涵盖本土与外来的草本双子叶植物、豆科草本、禾本科草本、灯心草、莎草以及木本多年生植物（包括藤本、灌木与乔木）。不同生长型的本土与外来植物总盖度在各处理组间并无显著差异（F₂,₉₆=0.45，P=0.83）。但植物盖度在高地与低地间（F₁,₉₆=18.22，P≤0.001）、不同调查年份间（F₁,₉₆=14.54，P≤0.001）、秋季与春季间（F₁,₉₆=16.25，P≤0.001）均存在显著差异，且盖度表现出年份与季节的交互效应（F₁,₉₆=24.08，P≤0.001）以及季节与海拔的交互效应（F₁,₉₆=5.00，P≤0.001）。所有处理组中，外来农用禾本科草本的盖度均最高（≥90%）。各植物生长型的盖度在低地均达到峰值。本研究结果显示，降低刈割频率可提升公路沿线本土草本与野生花卉的物种丰富度与盖度。研究表明，在本研究周期内，刈割的时机与强度对植物群落的物种组成影响极小。不过，每年仅进行1次刈割可保留农用植物的盖度，从而在公路路域维护中发挥侵蚀控制与土壤固持的作用。具体的主动管理措施可包括：本土植物种植、选择性施用除草剂以减少外来禾本科草本的入侵、仅在路边边缘至10米范围内进行定期刈割，以及仅在晚秋进行1次刈割并将刈割边界扩展至路边边缘外10米以外，以抑制木本植物的入侵，此举可降低长期维护成本。