Fig 1.
Maps of elevation, topography and Human Influence Index (HII) in Sardinia.
Maps on the spatial distribution of (a) elevation, (b) the simplified lithology subdivided into six categories: Quaternary sedimentary outcrops (Q_sedimentary), Tertiary limestone outcrops (T_limestones), Tertiary volcanic outcrops (T_vulc), Mesozoic limestone outcrops (M_limestones), Paleozoic metamorphic outcrops (P_meta) and Paleozoic intrusive outcrops (P_intrusive) and the (c) HII [28].
Fig 2.
Variance partitioning based on the GLM results for total EVPR, insular EVPR and exclusive EVPR and relative importance of each explanatory variable.
The Unexplained (U) and the explained variance of each group of explanatory variables (Human influence (Human), Climate, and Topography and geology (Topography)) are shown on the left. Figures on the right display the relative importance of each explanatory variable calculated as the normalised percentage contribution to the adjusted R2 for the respective response variable. See S3 Table for detailed values of the contribution of each group of and singular explanatory variable.
Table 1.
Results of generalized linear models (GLMs) showing the set of variables explaining richness of total, insular and exclusive Endemic Vascular Plant Species Richness (EVPR).
Fig 3.
Variations in EVPR of exclusive EVP, insular EVP and total EVP.
Variations in local EVPR (number of endemic plant taxa inside each 1 km grid cell) of exclusive EVP (a; N = 2466), insular EVP (b; N = 34375) and total EVP (c; N = 34603) are shown in the upper part of the figure. Variations in regional EVPR (number of endemic plant taxa inside each 100 m elevation interval) of exclusive EVP (d), insular EVP (e) and total EVP (f) are shown in the lower part of the figure. Variations in the area of territory considered (number of 1 km resolution grid cells at each elevation interval) were superimposed on both local and regional EVPR.