Biodiversity hotspots in southwestern Germany are losing their species richness

In southwestern Germany, regions that were once among the most diverse in plant life are now experiencing a decline in their biodiversity. A study coordinated by the Stuttgart State Museum of Natural History and published in Global Change Biology reveals that areas such as the Swabian Alb and the Black Forest, which were particularly rich in species at the beginning of the study period, have seen a decrease in their plant diversity over time.

Citizen scientists and professional botanists have contributed over 2.5 million plant observations to the Floristic Mapping of Baden-Württemberg project over the past five decades. These data, which span from 1970 to 2023, have provided valuable insights into the changes occurring in Germany and Central Europe's flora.

While some areas have gained new plant species, especially those with high diversity, the study reveals that diverse areas, or biodiversity hotspots, tend to lose diversity. This finding underscores the importance of considering the local context when it comes to biodiversity conservation. Simply preserving as many species as possible is not sufficient; conservation efforts must be tailored to the specific area and take into account the unique ecological characteristics and evolutionary distinctiveness of the plant species found there.

The research team, led by Dr. Viktoria Ferenc and Dr. Pierre Liancourt, analyzed the data using advanced statistical methods to identify patterns. They found that different aspects of biodiversity respond differently to local environmental conditions, such as climate, land use, atmospheric pollution, soil conditions, and topography.

Nitrogen-tolerant and disturbance-adapted species, as well as highly competitive or non-native plants, often spread, while habitat specialists such as wetland species, orchids, and conservation priority species frequently decline.

Conservation efforts must consider these local conditions and the specific traits and evolutionary distinctiveness of the plant species in question. Dr. Ferenc emphasizes that biodiversity conservation should not focus solely on increasing species numbers but should also consider which species are increasing or decreasing and the characteristics they possess.

The study highlights the value of long-term, coordinated citizen science and monitoring projects in capturing these changes and providing a foundation for biodiversity research, species conservation, Red List assessments, and nature conservation planning.