Plant distribution data for the Czech Republic integrated in the Pladias database

Research on the Czech flora has a long tradition and yielded a large number of records on the occurrence of plants. Several independent electronic databases were established during the last three decades in order to collect and manage these records. However, this fragmentation and the different characteristics of each database strongly limit the utilization and analyses of plant distribution data. Solving these problems was one of the aims of the Centre of Excellence PLADIAS (Plant Diversity Analysis and Synthesis. 2014-2018). which is also the source of the name of the central database of the project: Pladias - Database of the Czech Flora and Vegetation (www.pladias.cz). We developed an occurrence module as a part of the Pladias database in order to integrate species occurrence data on vascular plants in the Czech Republic for use in pure and applied research. In this paper, we present a description of the structure of this database, data handling and validation, creation of distribution maps based on critically evaluated records as well as descriptions of the original databases and explorative analyses of spatiotemporal and taxonomic coverage of the integrated occurrence data. So far we have integrated more than 13 million records of almost 5 thousand taxa (species, subspecies, varieties and hybrids). which came from five large national databases. seven regional projects and records collected within the PLADIAS project. The Pladias database is now the largest set of data on vascular plant occurrence in the Czech Republic, which is subject to continuous quality control. Analyses of this database pointed to differences in spatial and taxonomic coverage of the source datasets. However, it also showed that the targeted effort of experts focused on validating existing records, as well as the collection of new data is still necessary in order to obtain reliable distribution data for individual species.