Effect of climate change on fir forest communities in the mountains of South-central Greece

The endemic oro-Mediterranean fir (Abies spp.) forests in Greece are valuable ecosystems with high ecological and economic importance. In the mountains in south-central Greece, the availability of moisture plays a crucial role in the floristic composition, structure and distribution of fir forest communities. Because of the predicted adverse climate changes for the Mediterranean zone, suitability of many habitats for the growth of fir forests will change. This study aims to quantify the degree to which these forests will be affected by climate change. Current and future climatic conditions in the area studied were estimated for two periods of time (2041 – 60, 2061 – 80) and two climate change scenarios (RCP 4.5, RCP 8.5). Vegetation releves were classified and ordinated. Recursive partitioning was used to reveal the most important factor for discriminating the main plant communities and determining the ecological threshold between them. Current and future suitability of bioclimatic space for fir forest communities was identified. The effect of climate change was assessed based on predicted changes in the potential distribution, in terms of size and location, of fir forest communities. Two plant communities that reflect the differentiation of fir forests into xerophytic and mesophytic forest types are described. Among several climatic variables, spring drought was the best factor discriminating these two forest communities. The quantification of the threshold for drought in these two plant communities was used to predict their potential distribution in the area studied. Potential distribution of fir forests in south-central Greece will change in the future, due to a reduction in suitable bioclimatic space and shift to higher altitudes. The effect is expected to be greater for xerophytic forest communities, especially in the worst-case scenario (RCP 8.5) and in 2061–80.