A Special Issue dedicated to Professor Pier Luigi Nimis

This Special Issue is dedicated to Professor Pier Luigi Nimis on the occasion of his 70th birthday and retirement. It was our aim to publish papers addressing the three major research fields that Pier Luigi dealt with during his career: systematics and taxonomy, biomonitoring and ecology, and data resources and digitization. The papers in this Special Issue provide a vivid overview of the state of the art in the three research fields, and they reflect on Pier Luigi's outstanding contribution to lichenology. They offer a wide array of different methodologies, from the traditional approaches investigating lichen diversity and taxonomy by means of morpho-anatomical analyses, culture isolations and phylogenetic systematics, to the most modern sequencing techniques, and to the development of computer-aided tools and databases for facilitating lichen identification.