The contribution of roadsides to connect grassland habitat patches for butterflies in landscapes of contrasting permeability

Abstract

Roadsides, in particular those being species-rich and of conservation value, are considered to improve landscape permeability by providing corridors among habitat patches and by facilitating species' dispersal. However, little is known about the potential connectivity offered by such high-value roadsides. Using circuit theory, we modelled connectivity provided by high-value roadsides in landscapes with low or high permeability in southcentral Sweden, with 'permeability' being measured by the area of semi-natural grasslands. We modelled structural connectivity and, for habitat generalists and specialists, potential functional connectivity focusing on butterflies. We further assessed in which landscapes grassland connectivity is best enhanced through measures for expanding the area of high-value roadsides. Structural connectivity provided by high-value roadsides resulted in similar patterns to those of a functional approach, in which we modelled habitat generalists. In landscapes with low permeability, all target species showed higher movements within compared to between grasslands using high-value roadsides. In landscapes with high permeability, grassland generalists and specialists showed the same patterns, whereas for habitat generalists, connectivity provided by high-value roadsides and grasslands was similar. Increasing the ratio of high-value roadsides can thus enhance structural and functional connectivity in landscapes with low permeability. In contrast, in landscapes with high permeability, roadsides only supported movement of specialised species. Continuous segments of high-value roadsides are most efficient to increase connectivity for specialists, whereas generalists can utilize also short segments of high-value roadsides acting as stepping-stones. Thus, land management should focus on the preservation and restoration of existing seminatural grasslands. Management for enhancing grassland connectivity through high-value roadsides should aim at maintaining and creating high-value roadside vegetation, preferably in long continuous segments, especially in landscapes with low permeability.

Keywords

Corridors; Generalists; Landscape management; Road verges; Specialists; Stepping-stones

Published in

Journal of Environmental Management
2022, volume: 311, article number: 114846
Publisher: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

SLU Authors

• Lennartsson, Tommy

  • Department of Urban and Rural Development, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Swedish Biodiversity Centre

UKÄ Subject classification

Landscape Architecture
Environmental Sciences related to Agriculture and Land-use
Ecology

Publication identifier

• DOI: https://doi.org/10.1016/j.jenvman.2022.114846

Permanent link to this page (URI)

https://res.slu.se/id/publ/118362