Vegetation changes during a 30 year period in several stands above the forest line (Emilian-Apennines)

The study highlights the changes occurred in several stands of Hyperico richeri-Vaccinietum communities of the high Emilian Apennines after 30 years after the first phytosociological and phenological surveys. In 2012 the same types of surveys were repeated in the original stands, with the aim to detect any change in vegetation structure as well as in species composition and behaviour. The study has pointed out significant changes in all the vegetation stands over the last 30 years. The following trends are displayed in the stands analysed: A) a general decrease of species richness per stand; B) a slight increase of the shrubs/herbs cover ratio, with a significant spreading of Juniperus communis and of Vaccinium uliginosum, sometimes coupled with a reduction of V. myrtillus cover; C) a reduction of Orophytes and of many species belonging to the classes Caricetea curvulae and Nardo Callunetea; D) a xero-thermic trend of plant communities composition (index species analysis). It is noteworthy that many of the declining species flower in the dryest and hottest period of the year (July-August). The results seems to indicate that the changes in vegetation features are due only partly to human causes (lighter grazing) and more widely to climatic stress.