Management practices increase the impact of roads on plant communities in forests

The question of the interaction between management practices and road effects on forest biodiversity is of critical interest for sustainable practices and the conservation of forest communities. Forest road improvement and easier access to stand interiors via skid trails, are integral components of management. We tested whether skid trails and the use of limestone gravel for road improvement extended the road effect on plant communities further into forest habitats in a nutrient-poor environment. We analyzed how road distance and skid trail presence affect stand plant communities by examining species composition, distribution of biological and ecological traits, individual species responses and environmental plant indicator values. All results showed that the road effect extended deeper into forest on skid trails, i.e. up to 20 m and even 60 m, than off skid trails, i.e. up to 10 m. Skid trails served as penetration conduits for open-habitat species probably due to forest machinery traffic. The road effect was more damaging to forest species and less-competitive species on skid trails. Additionally, limestone gravel modified the acidity of adjacent poor soils, leading to a shift in species composition and to a colonization of the stand interior by basophilous species. We advocate minimizing skid trail density and using endogenous materials for roads to keep sections of forest large enough to conserve disturbance-sensitive forest species. The interaction found between road effects and management practices underlines the need to adopt a landscape-scale view and to consider multiple anthropogenic impacts in order to effectively preserve forest plant communities.