Power line corridors put the brakes on the extinction of plants in declining semi-natural grassland habitats
Written By Juliana Dániel-Ferreira, Riccardo Bommarco, Jörgen Wissman and Erik Öckinger
3rd March 2021
Are linear infrastructure habitats promoting biodiversity in all spatial scales?
Semi-natural grasslands are one of the most biodiverse habitats in Europe but most of them have been abandoned or transformed into forests or arable land. Many of the species that depend on these habitats are struggling to survive in the few remaining habitat fragments that are scattered throughout the landscape. However, the similarities between traditionally managed semi-natural grasslands and novel habitats such as road verges and power line corridors have recently been made evident. As the area of such infrastructure habitats increases, so does the interest in managing them for the benefit of plants and insects coupled to semi-natural habitats in order to slow down species losses. Adequate management in combination with appropriate environmental conditions in linear infrastructure habitats can result in high local species diversity, but whether this translates to higher diversity in landscapes with high density of these habitats is unknown.
How to determine whether linear infrastructure habitats benefit biodiversity in the landscape?
Exploring the effects of environmental change on the number of species and on their abundances is a common approach in ecological studies. However, changes in landscape structure do not affect all species in the evolutionary tree equally. Species that are closely related and share similar ecological traits could be more threatened due to their similarities in their responses to environmental change, which can in turn lead to losses in the stability of the ecosystem. Therefore, we investigated whether linear infrastructure habitats affect the three main aspects of diversity: species richness, evenness and evolutionary distinctiveness. How evolutionarily distinct a species is depends on its proximity to other species in the evolutionary tree: closely related species tend to share more similarities than species that are far from each other.
To be able to determine whether landscapes with high density of linear infrastructure habitats harbour more biodiversity than landscapes with low density, we selected 32 forest dominated landscapes (2 km x 2km areas, Fig.1) in Sweden with either high or low amounts of road verges and with or without power line corridors. Then, we surveyed plants, bumblebees and butterflies in several types of grassland habitat, including those along infrastructure, in each of these landscapes.
Fig. 1. a) Location of the 32 2 km x 2 km landscapes in Sweden and (b) study design. The grass illustration in the landscapes is simplified representation of the varying areas of semi-natural grasslands within all 32 landscapes.
Linear infrastructure habitats increase landscape-scale diversity of plants but not of flower-visiting insects
There was no effect of the size of the area of linear infrastructure habitat on the evolutionary distinctiveness of plants or insects. In addition, all landscape types had a similar species composition of plants and insects, indicating that linear infrastructure habitats do not provide the landscapes with species that cannot already be found in other semi-natural grassland habitats.
More importantly, landscapes with power line corridors had on average six more plant species than landscapes without power line corridors (Fig. 2), but there was no such effect on the number of insect species. The area of road verges in the landscape had no effect on the number of plant or insect species. We hypothesize that the additional plant species in landscapes with power line corridors will also eventually go extinct, as has occurred in landscapes without power line corridors, unless conservation measures are taken. Because of this, we recommend that semi-natural grassland habitats in landscapes with power line corridors should be prioritized for focussed conservation management.
Fig. 2. Average richness of plant species in landscapes with and without power line corridors. Species richness of plant species is on average ~ 6 species higher in landscapes with power line corridors than in landscapes without power line corridors. The grey bands represent the 95% confidence intervals. Note that the y-axis does not start at zero.
Recommendations for management and future research
Currently, only a tiny proportion of power line corridors and road verges are intentionally managed to enhance biodiversity, but due to their large areas they constitute a huge opportunity for biodiversity conservation. We recommend that much larger areas of road verges and power line corridors should be managed to promote biodiversity, but future research needs to evaluate the effects of different management options on biodiversity and how this can enhance their role at the landscape scale.
It is also important to determine the reason why road verges did not have any impact on plant and insect biodiversity at the landscape scale. We suspect that the benefits of additional habitat area and connectivity provided by this habitat are diminished by the effect of the road itself and traffic.
Author information:
Juliana Dániel-Ferreira, PhD student in Ecology at the Swedish University of Agricultural Sciences, Sweden.
Riccardo Bommarco, Professor in agricultural entomology at the Swedish University of Agricultural Sciences, Sweden.
Jörgen Wissman, Researcher at the Department of Urban and Rural Development at the Swedish University of Agricultural Sciences, Sweden.
Erik Öckinger, Associate professor and Senior lecturer at the Swedish University of Agricultural Sciences, Sweden.
Source:
Dániel-Ferreira, J., Bommarco, R., Wissman, J., & Öckinger, E. (2020). Linear infrastructure habitats increase landscape-scale diversity of plants but not of flower-visiting insects. Scientific reports, 10(1), 1-11. DOI: https://doi.org/10.1038/s41598-020-78090-y
Editor:
Julia Kintsch
Cite this summary:
Dániel-Ferreira, J., Bommarco, R., Wissman, J. & Öckinger, E. 2021. Power line corridors put the brakes on the extinction of plants in declining semi-natural grassland habitats. Edited by Kintsch, J. TransportEcology.info, Accessed at: https://transportecology.info/research/plants-in-powerline-corridors [Date accessed].
