Blossoms, Buds, Bayreuth

Bayreuth is a green city surrounded by lush nature: well-kept parks, colourful meadows, agricultural land, and diverse forests. Yet many of us don’t actually know what’s growing and thriving right on our doorstep. The ÖBG sees it as one of its main tasks to impart knowledge about plants, inspire people to engage with nature, and kindle a fascination for the diversity of local flora. This has now been made easier with the Flora of Bayreuth and Surroundings, a book produced after years of mapping work led by the ÖBG. “Our book provides a foundation for people to go outside and enjoy exploring the local plant world,” says Dr Gregor Aas, former head of the ÖBG and one of the initiators of the mapping project that led to the book. In addition to illustrated and annotated descriptions of plant species found in Bayreuth and the surrounding area, the book includes information on the climate and geology of the mapped area, the historical growth of settlements in Bayreuth and its surroundings, and the history of botanical research in the region. The book is suitable as both a textbook and a reference work or field guide.

Documenting the flora is also essential in light of climate change and the associated loss of biodiversity in terms of species and habitats. This data allows specialists to detect changes in plant life and take appropriate measures for conservation. The book doesn’t just highlight the current diversity of plant species; it also shows what has already been lost. With the help of historical sources dating back to the 17th century – including both written works and dried, pressed herbarium specimens – the team has identified over 300 species that once grew in Bayreuth and its surroundings but are now extinct. “Researching these historical sources was typical winter work for the time when we couldn’t collect data outdoors,” says Dr Marianne Lauerer, Academic Director at the ÖBG and one of the initiators of the Flora of Bayreuth and Surroundings.

From spring through autumn between 2009 and 2021, Aas and Lauerer, along with University of Bayreuth students and volunteer plant enthusiasts, mapped an area of over 134 square kilometres, documenting the presence and frequency of more than 1,600 plant species. To achieve this, the core group met nearly every week to systematically record wild-growing plants in Bayreuth and its surroundings. “In addition, many other people reported plant sightings to us. The real challenge was bringing all these different findings together,” says Aas.

Photos: Marianne Lauerer und Julia Kruse

Since the early 2000s, the ÖBG has regularly documented all plant species that establish themselves spontaneously on the grounds of the botanical garden. “The ÖBG is home to many non-native species, and our garden contains a variety of diverse habitats, some quite close to natural conditions. Therefore, it’s our responsibility to monitor which species, native or non-native, are also growing wild here,” says Aas. This inspired the idea in 2009 to expand plant documentation to all of Bayreuth and its surroundings. “We chose a ‘messtischblatt’ – a map at a 1:25,000 scale – with Bayreuth and the ÖBG at the centre as our study area. This way, the data from our project is compatible with other works and can be integrated into larger databases like the Flora of Bavaria, making it more broadly accessible and secure,” explains Lauerer.

The goals of the mapping project, according to Lauerer: “As comprehensive, as complete, and as precise as possible.” To achieve this last goal, the mapping group recorded the locations of about 1,300 plant species with GPS. “These are particularly interesting species. Common and widespread plants, like daisies, were not GPS-mapped,” says Lauerer.

Over the years, an enormous dataset of over 50,000 entries has been compiled. This has grown so large that experts in IT were brought in to manage it. Anna Walentowitz and Reinhold Stahlmann from the Chair of Biogeography at the University of Bayreuth built a database and created maps pinpointing the GPS-recorded species locations.

This extensive data will be further analysed in a master’s thesis starting this winter. “So far, the data is descriptive, meaning it shows where and how often a species occurs. But we would like to know, for example, the biodiversity of certain habitats, such as the natural Rotmainaue, agricultural land, or urban areas, or what proportion of new, non-native species – so-called neophytes – are present in our flora,” says Lauerer. This dataset provides ample research opportunities for students.

Ultimately, the data also serve as a foundation for future mapping, which already began in summer 2024. “Given climate change, we want to continue the project and perhaps, in ten or twenty years, conduct another analysis to see how the flora in and around Bayreuth has changed,” says Aas.