Outside the forest stand: Analysis of urban forest buffer zones to implement nature−based solutions – A case study of Poznań (Poland)

Urban forests are important and highly valuable natural elements of urban green infrastructure (GI). The tightening of developed areas in the vicinity of urban forests results in negative changes in water relations, the disruption of the continuity of wildlife corridors, and the growing number of users, which has an impact on the degradation of urban forest ecosystems. This study, conducted in Poznań, Poland, provides an analysis of urban forest buffer zones regarding land use type, the high greenery ratio, and the planning decisions that could serve as a nature−based solution (NbS). The study shows a significant change in developed land area in the urban forest buffer zones with the width of 500 m and 100 m. That change occurred between 1997 and 2019 and should be a matter of concern. Coverage of the buffer zones with high greenery, which turned out to be very diverse, could be treated as a forest extension and an element mitigating the negative transition between the forest and the city. Different land use types were taken into consideration, especially in developed areas. The buffer zones of urban forests should be developed with spatial planning tools like data management and decision−making to mitigate the negative impact of the developed areas on the forests. The development of the concept of supporting green infrastructure in urban forest buffer zones, regardless of land use type was also part of the study.