The influence of past land-use on understory plant distributions in a near-natural deciduous forest in Denmark

In regions with a long cultural history, past land-use may strongly determine floristic composition in seemingly natural vegetation. Here we examine if past land-use affects understory plant distribution in near-natural forest in a historically and environmentally heterogeneous setting, namely the 17 ha freshwater island of Borgnr (Denmark). In 107 randomly located 100 m² plots we recorded species composition and various environmental variables. The plots were classified into three groups according to past land-use: (1) Disturbed sites close to 12^th and 20^th century ruins and associated open areas; (2) formerly grazed meadow areas; and (3) forested sites without indications of strong anthropogenic influence. Past land-use, environmental variables and species traits were used to interpret floristic gradients. Unconstrained and constrained ordinations clearly separated plots with different past land-use, and showed that the main floristic gradients on Borgø correlated with hydrological-edaphic conditions and past land-use. Partial constrained ordination using the environmental parameters as covariables showed that past land-use had a unique influence on floristic composition.