Exploring patterns of beta‐diversity to test the consistency of biogeographical boundaries: A case study across forest plant communities of Italy

Abstract

Aim To date, despite their great potential biogeographical regionalization models have been mostly developed on descriptive and empirical bases. This paper aims at applying the beta‐diversity framework on a statistically representative data set to analytically test the consistency of the biogeographical regionalization of Italian forests. Location Italy. Taxon Vascular plants. Methods Forest plant communities were surveyed in 804 plots made in a statistically representative sample of forest communities made by 201 sites of Italian forests across the three biogeographical regions of the country: Alpine, Continental, and Mediterranean. We conducted an ordination analysis and an analysis of beta‐diversity, decomposing it into its turnover and nestedness components. Results Our results provide only partial support to the consistency of the biogeographical regionalization of Italy. While the differences in forest plant communities support the distinction between the Alpine and the other two regions, differences between Continental and Mediterranean regions had lower statistical support. Pairwise beta‐diversity and its turnover component are higher between‐ than within‐biogeographical regions. This suggests that different regional species pools contribute to assembly of local communities and that spatial distance between‐regions has a stronger effect than that within‐regions. Main conclusions Our findings confirm a biogeographical structure of the species pools that is captured by the biogeographical regionalization. However, nonsignificant differences between the Mediterranean and Continental biogeographical regions suggest that this biogeographical regionalization is not consistent for forest plant communities. Our results demonstrate that an analytical evaluation of species composition differences among regions using beta‐diversity analysis is a promising approach for testing the consistency of biogeographical regionalization models. This approach is recommended to provide support to the biogeographical regionalization used in some environmental conservation polices adopted by EU.

Lichen Distribution Patterns in the Ecoregions of Italy

“…In particular, larch and stone-pine forests of the Subalpine ecoregion were found to be a hotspot of lichen diversity of particular conservation concern [21][22][23]. As far as the Montane ecoregion is concerned, the high species richness is probably related to its wide latitudinal extent, since it ranges throughout the country, spanning a relevant biogeographic gradient [24,25]. This should be reflected in heterogeneous community composition across sites [1], a pattern which would, however, require further investigation.…”

Community weighted mean trait data of Italian forest understories

“…The sampling design was systematic and probabilistic and was based on a grid superimposed onto the whole Italian country (16 km × 16 km cells), with each corner of the grid being included as a sample area if a forest larger than 1 ha was found there after a field assessment [3]. The sampling design is part of the ICP Forests Level I network having as the main objective to monitor the health status of the European forests (http://icp-forests.net/).…”

Anthropogenic‐driven transformations of dragonfly (Insecta: Odonata) communities of low elevation mountain wetlands during the last century

“…The analysis was conducted in two and three dimensions choosing as final configuration the one which minimised the stress value. Additionally, the results' quality was evaluated by stressplots (Borcard et al ., 2018; Chiarucci et al ., 2019).…”

“…Positive values indicate the separation between groups. R > 0.75 indicate sharp separability between groups, 0.5 < R ≤ 0.75 good separability, 0.25 < R ≤ 5 partial overlapping, 0 < R ≤ 0.25 important overlapping (Chiarucci et al ., 2019). Significance of ANOSIM comparison was computed based on 9999 permutations.…”