The decline of freshwater flora due to alteration, reclamation and trophic perturbation of lowland wetlands is among the most relevant issues in biological conservation. The contribution of heavily modified water bodies (HMWBs) in preserving plant diversity is notable, but the underlying ecological mechanisms are not completely explored. To contribute to this debate and expand the knowledge on the role of HMWBs in maintaining wetland biodiversity in overexploited agroecosystems, a canal network of about 1150 km (SE Po valley, N-Italy) was analysed to study the geographical patterns of riparian flora and plant communities, and their land use and hydrochemical drivers. A systematic sampling procedure was adopted by randomly selecting 96 transects (10 m²) along 79 drainage canals. Additionally, 22 transects were sampled for water quality evaluation. Flora was characterised based on species richness and presence of threatened, alien and invasive species. We also studied the contribution of land use and water quality in explaining plant richness and composition. Slope and aspect of canals do not significantly affect plant species composition, whereas the «proximity to protected areas» seems to have a negative influence. Both threatened and alien plants richness decrease approaching protected areas. Among land use types, only agro-zootechnical settlements influence plant species composition, favoring nitrophilous species, as demonstrated by water parameters (the spatial patterns of nitrophilous species mirrored the progressive worsening of canal waters). This work confirms the key role of HMWBs in sustaining plant species diversity in oversimplified landscapes, highlighting complex regulation mechanisms that need further investigations.

由于低地湿地的改变、开垦和营养扰动而导致的淡水植物群减少是生物保护中最相关的问题之一。重度改良水体 (HMWBs) 在保护植物多样性方面的贡献是显着的，但其潜在的生态机制尚未完全探索。为了促进这场辩论并扩大关于 HMWB 在过度开发的农业生态系统中维持湿地生物多样性的作用的知识，分析了约 1150 公里（SE Po 河谷，N-意大利）的运河网络，以研究河岸植物的地理格局社区及其土地利用和水化学驱动因素。通过随机选择96个样带（10 m ²) 沿 79 条排水渠。此外，还采样了 22 个样带进行水质评估。植物区系的特点是基于物种丰富度和受威胁、外来和入侵物种的存在。我们还研究了土地利用和水质在解释植物丰富度和组成方面的贡献。运河的坡度和坡向不会显着影响植物物种组成，而“靠近保护区”似乎有负面影响。靠近保护区的受威胁植物和外来植物的丰富度都会减少。在土地利用类型中，只有农业畜牧业定居点影响植物物种组成，有利于嗜硝化物种，如水参数所示（嗜硝化物种的空间格局反映了运河水域的逐渐恶化）。