Roadsides: an opportunity for biodiversity conservation

Abstract

Questions How do roadsides interact with patches of natural vegetation in shaping perennial plant communities in fragmented agricultural areas? Are the observed differences due to the type of roadside (i.e. roadcuts, embankments or road verges) or are there other factors driving community structure and composition? Location Stretch of motorway A3 and its surrounding area, central Spain. Methods We analysed the variation in perennial plant species composition and diversity among 92 plots (400 m2). The plots were located in five different environmental scenarios, three of them in a fragmented landscape (patches of natural vegetation, embankments and roadcuts) and two in an unfragmented landscape (natural vegetation and road verges). In each plot, the cover of each perennial plant species and eight soil variables were assessed. We used phi coefficient of correlation to determine the scenario preferences of each species, Kruskal–Wallis tests to compare the soil variables between landscape scenarios and eight descriptive variables of the community, and RDA and partial RDA to evaluate the relative importance of the type of environmental scenario on the floristic community. Results We identified 130 species, with only 16 species never appearing on roadsides. Perennial total cover, species richness, inverse Simpson's index and number of protected species showed no significant differences between the five scenarios considered. In contrast, the number of nutrient‐demanding species and restricted‐range diversity had lower values in natural vegetation plots. Soil variables and the type of scenario together explained 28.5% of the species composition variation. Of this percentage, 6.8% was explained by soil variables, 12.1% by the type of scenario and 10.0% of the variation was shared between the two data sets. Conclusions Our results show that almost all perennial species occurring in natural vegetation patches were also able to reach and settle in roadsides. However, soil conditions and other specific roadside variables generate different plant communities. In spite of the differences found between the perennial plant community of roadsides and their surrounding area, roadsides are excellent reservoirs of biodiversity.

Three years of vegetation development worth 30 years of secondary succession in urban‐industrial grassland restoration

“…This study demonstrates that there is no single “best method” for restoration; the selection should be based on the particular demand and circumstances (Adams, Hodge, Macgregor, & Sandbrook, ; Shackelford et al., ). Multiple constraints exist in all restoration projects, but in case of intensively modified landscapes, like urban‐industrial sites, efforts needed to handle the constraints can be higher (Arenas, Escudero, Mola, & Casado, ). This guidance helps to select the appropriate method in future projects, linked to the green infrastructure policy of the European Union (European Commission, ).…”

The contribution of constructed green infrastructure to urban biodiversity: A synthesis and meta‐analysis

“…Interestingly, the effects of roadsides and wetland detention basins relative to conventional counterparts were infrequently studied when compared to other GI types despite their high frequency and importance in urban environments. Road ecology has been a field of study for several decades and previously research has highlighted that when managed, can be rich in both native and planted species (Arenas, Escudero, Mola, & Casado, 2017;Arifin & Nakagoshi, 2011). Further exploration of the potential to vegetate roadsides could have significant effects on biodiversity because of the large area they occupy in cities and high degree of connectivity roadways share to natural habitat or other GI types (von der Lippe & Kowarik, 2008).…”

Genetic diversity and connectivity in fragmented populations of Rhinanthus minor in two regions with contrasting land-use

“…Effective landscape-scale conservation strategies will require an understanding of the connectivity provided by gene flow between protected sites but will also benefit from knowledge about such connectivity across the landscape matrix. The landscape matrix can be an important influence on plant species diversity in isolated sites both in terms of surrounding land use types and availability of other potential habitat patches such as roadside verges (Schmucki et al 2012;Arenas et al 2017). For example, species richness of grassland plants was found to be significantly lower in areas dominated by arable land than it was in forested landscapes (Öckinger et al 2012).…”

“…A review of the impact of fragmentation on plant populations has identified a knowledge gap concerning the role of the landscape matrix (Ibáñez et al 2014). Reference has already been made to the potential part played by linear landscape elements in plant dispersal (Arenas et al 2017;Thiele et al 2018) but there is still some debate about the role of these features. Other studies have found that large high-quality habitat patches are required for plant population persistence and that dispersal along linear elements in agricultural landscapes was limited (Soons et al 2005;Liira et al 2009).…”