The influence of adjacent land-use on road verges in the Swartland Region, South Africa.

Natural biodiversity is under threat from habitat destruction and fragmentation, partially caused by roads. Road verges provide potential avenues for invasion of alien species, while at the same time offering connectivity of the landscape on a large scale. This study aims to assess the ecological health of road verges in the Swartland area, South Africa and make recommendations on mitigating the threat of aliens while at the same time maximising biodiversity conservation. Road verges adjacent to non-agricultural areas showed lower species richness, while species abundance differed significantly (Mann-Whitney U-tests, p < 0.05) to most other land-uses. When comparing crop types, road verges adjacent to wheat fields differed significantly to all other crops types (Mann-Whitney U-tests, p < 0.05), with the lowest number of species encountered per transect. Jaccard Similarity Indices showed that samples differed in species composition, relative to adjacent land-use. It is recommended that road verges should be adaptively managed to promote recruitment of natural species and suppress the establishment of exotics. Where possible, road verges should be made as wide as possible to promote their use as refugia by various fauna. Finally, more extensive research efforts should be poured into road verges in order to fully realise their potential.

自然生物多样性正受到栖息地破坏和碎片化的威胁，部分原因在于道路建设。道路两侧为外来物种的入侵提供了潜在通道，同时也在大规模上促进了景观的连通性。本研究旨在评估南非斯瓦特兰地区道路两侧的生态健康状况，并提出减轻外来物种威胁的同时最大化生物多样性保护的建议。毗邻非农业区域的道路两侧物种丰富度较低，而物种丰度与大多数其他土地利用方式存在显著差异（Mann-Whitney U检验，p < 0.05）。在比较作物类型时，毗邻小麦田的道路两侧与其他所有作物类型存在显著差异（Mann-Whitney U检验，p < 0.05），每个样带遇到的物种数量最少。Jaccard相似性指数表明，样本在物种组成上与相邻土地利用方式存在差异。建议对道路两侧进行适应性管理，以促进自然物种的繁殖并抑制外来物种的建立。在可能的情况下，应尽可能拓宽道路两侧，以促进其作为各种生物避难所的使用。最后，应投入更多广泛的研究努力，以充分发挥道路两侧的潜力。