Open oakwoods facing modern threats: Will they survive the next fifty years?

Abstract

Open oakwoods are ancient but currently vanishing plant communities of high conservation value. We studied the vegetation of Eurasian steppic oakwoods in the Czech Republic where they are at the westernmost outcrop of their potential distribution to understand ecosystem changes and their drivers in the period of modern environmental change. In 2012, we resampled a set of semi-permanent plots established in 1965. Long-term compositional shifts and biotic homogenization were linked mainly to eutrophication and canopy closure. Ecological groups of nitrophytes and neophytes increased, while assemblages of species characteristic for open woodlands declined. This process can be attributed to several factors including changes in forest management, the rise of the native woody species Tilia cordata, airborne nitrogen input to generally nutrient-poor substrates and subsequent increase of invasive plant species, and finally to increased wildboar density. The decline of the unique communities of open steppic oakwoods will likely continue under the current management, increased nitrogen availability and canopy closure. Although reintroducing the wide range of historical forest uses is not realistic, the removal of Tilia individuals, reduction of the wild boar population and the promotion of Quercus to maintain the open-canopy structure may moderate the shift towards novel communities and help to restore open oakwoods.