The list of ancient-forest plant species revisited – Field verification in the Carpathian ancient and recent forests

Abstract

Existing lists of ancient-forest species – taken to indicate stands with no record of agricultural use – in general relate to the deciduous and mixed forests of Europe (i.e. the European Hermy’s list and the Polish Dzwonko and Loster’s list). We hypothesised that these lists might in fact be too general to prove useful in assessing and managing the forests in any individual region, and all the more so where the region in question has specific environmental (e.g. mountainous) conditions. Our goal was therefore to develop a list of ancient-forest species for a particular mountain region – the NE Carpathians – and then to assess how that compares with the aforementioned lists of broader (Polish or European) scope already existing. As we also sought insight into the ecological drivers behind the plant composition of recent forests, our further goal was to identify and discuss differences in ecological characteristics between the plant species that are significantly more common in either our ancient or our recent forests. To that end, we collected 294 phytosociological relevés in ancient and recent forests to compare the frequency and cover of each species present. To analyse their ecological characteristics we used environmental data collected in the field, as well as the plant functional traits. We then parametrised multiple regression models to find the most important predictors of differences in species frequency between recent and ancient forests. Ultimately, our results revealed just 15 understory species (out of 215) with significantly higher cover and frequency in ancient forests, along with 9 species with significantly higher cover in recent forests. We also showed that plant life form, leaf persistence and dispersal mode are predictors best explaining differences in frequency between recent and ancient forests. The results of the model showed that understory species in ancient forests were significantly more often geophytes, with green leaves from early spring to early summer and dispersed by ants. In turn, in recent forests, species were significantly more often characterised as therophytes with green leaves during summer. We conclude that the lists of ancient-forest species compiled for Poland and Europe are not entirely representative for the NE Carpathians. Moreover, there are three species (Brachypodium sylvaticum, Impatiens noli-tangere and Circaea lutetiana) shown as no longer warranting a status as ancient-forest species, given that they actually occurred significantly more often in the studied recent forests.