The Role of Brownfields and Their Revitalisation for the Functional Connectivity of the Urban Tree System in a Regrowing City

The connectivity of green infrastructure facilitating the movement of organisms is the key to strengthening biodiversity in cities. Brownfields are a valuable land resource, with their revitalisation as a Nature Based Solution high on the policy agenda. In supporting cities which simultaneously aim for densification and the maintenance or further development of greenery, this paper develops a model for identifying and prioritising the role of revitalised and prevailing brownfields for the connectivity of green infrastructure using the example of Leipzig, Germany. Comparing metrics between land use categories, brownfields have a central role as stepping stones, with a value of 13%, while revitalised brownfields substantially contribute to global connectivity, with a value of 87% being equally important, for example, with Leipzig's central parks. This paper's spatial-explicit network approach provides a complementary planning tool for prioritising brownfields and the added value of their renaturing by identifying (a) strategic functional corridors formed by brownfields, (b) the connectivity relevance and exposure of individual brownfields, and (c) how renatured brownfields would strengthen existing corridors and form alternative paths. This paper presents an approach using freely available software tools and high-resolution canopy data as a proxy for functional connectivity which serves as a standardised and comparable ex-ante evaluation of NBS strategies being implemented in other cities.

Automated summary

The connectivity of green infrastructure is crucial for enhancing biodiversity in cities. Revitalising brownfields as a Nature Based Solution is being prioritised, supporting cities' goals of densification and greenery development. This paper introduces a model using Leipzig, Germany as an example to identify and prioritize the role of revitalised and existing brownfields in green infrastructure connectivity. Comparing metrics, brownfields serve as important stepping stones (13%), and revitalised brownfields significantly contribute to global connectivity (87%), similar to Leipzig's central parks. The spatial-explicit network approach presented in this paper offers a planning tool to prioritize brownfields and assess the added value of their renaturing by identifying strategic corridors, connectivity relevance, and potential alternative paths. Furthermore, the study proposes a standardized evaluation of NBS strategies using freely available software tools and high-resolution canopy data.