Spatial data for fungal specimens: retrospective georeferencing and practical recommendations for mycologists

Abstract

The number of studies based on herbarium data for analyzing biogeographical patterns and environmental questions is increasing, as herbaria are making their collections available online. However, the quality of a specimen's spatial data still varies dramatically among records. Most historical specimen records either lack geographic information or have only vague textual descriptions about the locality, while contemporary records may exhibit unwarranted variation in spatial data quality, requiring increased awareness among mycologists about the importance of high quality primary spatial data for specimens. Georeferencing is the process of assigning geographic coordinates to a record linking it to a geographic location on Earth, and it can be processed retrospectively for records without geographical coordinates based on locality descriptions or directly collected in the field using GPS handheld units. Here we provide an overview of methods for georeferencing historical data retrospectively, discuss practical recommendations for collecting high quality spatial data for fungal specimens, and suggest decimal degrees as a standard form for citing geographic coordinates.