Thirty Years Population Monitoring of Orchis mascula subsp. speciosa in the Austrian Waldviertel

Orchids play an important role in nature conservation and are often used for monitoring purposes. However, interpreting orchid monitoring data can be challenging for several reasons. We present here the first monitoring data of Orchis mascula subsp. speciosa from the Bohemian Waldviertel region in Austria, where this taxon is ‘endangered’. The data show a successful spread into mesotrophic grassland, which was historically arable land, and afterwards strong population fluctuations. Within ten years, the population has grown from 50 flowering individuals to more than 800. Over the next 20 years, the population fluctuated between fewer than 200 and more than 1800 flowering individuals. We discuss these observations against the background of land use changes and different management measures (i.e., ploughing, grazing, mowing, and sowing of grassland species). Furthermore, we more generally discuss the potential of European terrestrial orchids to act as ‘pioneers’ and to successfully establish in fallow land. Finally, monitoring data for Orchis mascula from six countries was compiled and interpreted, given the various biological characteristics of orchid species. Reviewed data showed complex, multifaceted patterns, which still do not allow generalized conclusions explaining population dynamics.