Influence of stand attributes and skid trail area on stand-scale ground flora diversity

Abstract

Mechanisation is increasingly used in European forest management, but so far, few studies have investigated the combined effects of stand attributes and skid trails on stand-scale ground flora diversity. Our study assessed the effects of stand attributes (age, stand type, basal area) and skid trail area on ground flora diversity in 400 m2 plots in oak forest stands in the northern half of France. We calculated the richness and abundance of ecological groups based on successional status and light preference. We developed and compared generalized linear models and assessed the magnitude of the effects of each variable. At the ecological group level, floristic variations among plots were mostly associated with stand attributes (stand type or basal area). Although we found non-negligible effects of skid trails on all herbaceous groups, these effects disappeared when tree stand attribute effects were incorporated into the statistical models. At the species level, when incorporating stand attribute effects into the models, skid trail area had weak or inconclusive effects on species (occurrence > 25%) abundance. Because mechanisation is a recent practice in European forests, stronger effects might be expected in the long term.