Anthropogenic linear gaps in managed forests - Plant traits are associated with the structure and function of a gap

The impact of anthropogenic linear gaps (such as roads, paths, and drainage ditches) on the diversity and other features of the flora of managed forests is still poorly studied. The main aim of our study was to analyse the plant trait responses to the presence of drainage ditches and forest roads. These two kinds of anthropogenic gaps differ in their structure (microtopography) and function. The functional traits of species in plots containing different anthropogenic linear gaps were compared with those in plots without such gaps inside surrounding forests. The floristical composition of 838 plots was analysed by RLQ ordination followed by fourth-corner analysis. Both drainage ditches and forest roads were characterised by a significantly higher number of species than the surrounding forests. However, they differed with regard to their functional traits. The presence of a road was positively associated with occurrence of plants whose propagules are dispersed by wind, water or by transportation on the outside of vertebrate animals, as well as with occurrence of species that have upward dynamic tendencies in a number of localities in the country scale. The floristic composition of plots lying inside the forests was also associated with the same traits but the relationship was reversed. By contrast, ditches did not show any associations with species traits. The influence of linear gaps on the pattern of species functional traits depends on the degree of habitat diversification associated with a given structure and whether its functioning involves the movement of people and vehicles.