Local infrastructure interventions, such as existing blue (aquatic), and green (terrestrial) infrastructures for storm-water management and climate adaptation – can also aid biodiversity in human-dominated landscapes. This study of the Swiss lowlands used amphibian monitoring and species distribution data as well as connectivity modelling, to find key landscape elements of regional importance and local opportunities for urban blue-green infrastructure that could help enhance habitat connectivity.
Amphibians are a good indicator for the implementation potential of blue-green infrastructure at strategic locations. These infrastructures can enhance amphibians’ ability to move between terrestrial and wetland areas, and to different spawning sites. Their regular movement between blue and green core habitats means amphibians are particularly sensitive to decreases in landscape permeability and connectivity caused by urbanisation. This permeability and connectivity is essential for amphibian survival in fragmented landscapes, and, therefore, blue-green infrastructures offer potential to mitigate the decline in some amphibian populations. The resultant increased connectivity enhances ecosystem health and, as such, biodiversity more broadly.
The researchers assert that blue infrastructure is often not included in urban planning, with the focus being on green infrastructure. This study develops an integrated approach to model opportunities for blue-green infrastructure to enhance biodiversity in human-dominated areas. Developing a framework for planning urban blue-green infrastructures to help preserve biodiversity and maintain habitat connectivity, aids the EU in meeting its commitment to the and the EU’s Biodiversity strategy 2030.
The study area in the Swiss lowlands included distributed small settlements (in the Canton of Aargau) as well as major urban centres (such as the cities of Zürich and Winterthur) in the Canton of Zürich. Most of the study area was agricultural land (43% meadows and pastures), the rest was composed of forests (31%), urban settlements (22% – containing approximately 10% urban green spaces), water bodies (4%) and less than 1% raised bogs, fens and rocks or sandy ground. The researchers considered various protected blue and green areas in this area – including local and regional parks, amphibian breeding sites of national importance and sites belonging to the convention on wetlands and the Emerald Network.
The researchers selected ten species of amphibian, to cover different habitat and dispersal requirements: common midwife toad (Alytes obstetricans), yellow-bellied toad (Bombina variegate), common toad (Bufo bufo), European tree frog (Hyla arborea), Alpine newt (Ichtyosaura alpestris), palmate newt (Lissotriton helveticus), smooth newt (Lissotriton vulgaris), common frog (Rana temporaria), fire salamander (Salamandra Salamandra) and northern crested newt (Triturus cristatus). They obtained species data from 2017 to 2019, from the Coordination Centre for the Protection of Amphibians and Reptiles of Switzerland ().
The researchers used remote sensing and highly spatially resolved land-cover data, including gardens, public parks, cemeteries and green spaces of sports facilities in urbanised areas. Their framework integrated models of species distributions with connectivity modelling – which identified species-specific suitable habitats, hotspots of amphibian biodiversity, ecological corridors and opportunities for blue-green infrastructure in urbanised areas to enhance broader landscape connectivity. The researchers used migratory data from field observations in the study area to validate movement patterns of amphibian species.
The analysis identified species-specific distributions and amphibian biodiversity hotspots important for species conservation prioritisation and assessment of the current degree of conservation provided by existing protected areas. They also found four landscape elements essential to amphibian mobility at the regional scale: forest edges, wet-forest habitats, soils with variable moisture and riparian zones (interfaces between land and a river or stream). The researchers found that cities can also make a substantial contribution to wider landscape habitat connectivity – and say that, in the study area, up to 15% of urban space could be utilised in this way.
The findings for this study area in the Swiss lowlands highlight the importance of planning blue-green infrastructure locally in strategic locations across urban and peri-urban areas to create ‘stepping-stone’ habitats enhancing regional connectivity. The researchers propose areas for implementation of this infrastructure in the specific study area. They also suggest the integrated assessment framework developed for this study could help other regional conservation actions on priority areas and species: to efficiently direct conservation efforts, involve urban planners more strategically, and support broader landscape connectivity essential for biodiversity protection.
Donati, G.F.A., Bolliger, J., Psomas, A., Maurer, M., Bach, P.M. (2022) Reconciling cities with nature: Identifying local blue-green infrastructure interventions for regional biodiversity enhancement. Journal of Environmental Management, 316: 115254.
To cite this article/service:
“Science for Environment Policy”: European Commission DG Environment News Alert Service, edited by the Science Communication Unit, The University of the West of England, Bristol.
Notes on content:
The contents and views included in Science for Environment Policy are based on independent, peer reviewed research and do not necessarily reflect the position of the European Commission. Please note that this article is a summary of only one study. Other studies may come to other conclusions.
- Publication date
- 16 November 2022
- Directorate-General for Environment