Spatial patterns of vascular plant species richness in Poland: Relations among species group richness and hot spot distribution

Knowledge of spatial patterns of species richness (SR) is highly relevant for theoretical research in ecology and the development of conservation plans. In Poland, despite a long tradition of botanical surveys, vascular plant SR has not been mapped, nor have the correlations in richness among different plant species groups been explored at the entire country scale. Here, we used a recently published data set to examine spatial patterns and relationships among the joined SR of vascular plant species, including native species, archaeophytes, neophytes, and species with high conservation value (i.e., red-list species). The basic spatial unit employed was a 10 × 10 km grid from the Atlas of Distribution of Vascular Plants in Poland (ATPOL). We found that SR of native species and archaeophytes, neophytes, and red-list species were positively correlated. The main patterns of SR and the percentage of particular groups in the joined SR were based on three components: (1) gradient of overall SR, (2) invasion level, and (3) peculiarity of flora in some regions resulting from the high number and proportion of rare species that often have high conservation value (red-list species). In general, northeastern Poland was species-poor, while the Carpathian Mountain range, the uplands in southern Poland, and some parts of Wisła River valley had the highest SR concentrations. e location of SR hotspots usually did not overlap with the existing national parks system. The correlations among native SR, high conservation value species, and neophyte SR suggest that biological invasions are among the most important threats to vascular plant diversity in Poland. Finally, despite likely biases in SR assessments, we demonstrated that the presented maps seem to reflect general ecological gradients influencing vascular plant distribution in Poland.