Plant diversity in hedgerows and road verges across Europe

Abstract

1. Linear landscape elements such as hedgerows and road verges have the potential to mitigate the adverse effects of habitat fragmentation and climate change on species, for instance, by serving as a refuge habitat or by improving functional connectivity across the landscape. However, so far this hypothesis has not been evaluated at large spatial scales, preventing us from making generalized conclusions about their efficacy and implementation in conservation policies.2. Here, we assessed plant diversity patterns in 336 vegetation plots distributed along hedgerows and road verges, spanning a macro-environmental gradient across temperate Europe. We compared herb-layer species richness and composition in these linear elements with the respective seed-source (core) habitats, that is, semi-natural forests and grasslands. Next, we assessed how these differences related to several environmental drivers acting either locally, at the landscape level or along the studied macro-ecological gradient.3. Across all regions, about 55% of the plant species were shared between forests and hedgerows, and 52% between grasslands and road verges. Habitat-specialist richness was 11% lower in the linear habitats than in the core habitats, while generalist richness was 14% higher. The difference in floristic composition between both habitat types was mainly due to species turnover, and not nestedness. Most notably, forest-specialist richness in hedgerows responded positively to tree cover, tree height and the proportion of forests in the surrounding landscape, while generalist richness was negatively affected by tree height and buffering effect of trees on subcanopy temperatures. Grassland and road verge diversity was

Roadside diversity in relation to age and surrounding source habitat: evidence for long time lags in valuable green infrastructure

“…Grasslands are characterised by an open ground‐flora including several grassland specialists, although trees are generally present in most grasslands. Road verges classed as having (relatively) low surrounding source habitat had <5% (1–4%) semi‐natural grassland within a 500‐m surrounding buffer of the road verge (a typical landscape size for studies of ecological time lags and linear habitat elements, e.g., Cousins & Vanhoenacker, 2011; Vanneste et al., in press). Verges with relatively high levels of source habitat had at least 15% semi‐natural grassland in the buffer (usually 15–20%, but up to 31%).…”

“…The majority of research into the biodiversity effects of roads has been conducted on plants (Bernes et al., 2017). In addition to providing functioning habitat patches for low‐competitive grassland specialists species that depend on long‐term, regular and low‐intensity grassland management (Lindborg et al., 2014; Vanneste et al., in press), roads and road verges can also act as dispersal corridors for target species (Auffret & Cousins, 2013; Suárez‐Esteban, Delibes, & Fedriani, 2013). On the other hand, previous work has also shown that road verges are often associated with the occurrence and spread of invasive alien species (Ansong & Pickering, 2013; Lázaro‐Lobo & Ervin, 2019).…”

Hedging against biodiversity loss: Forest herbs’ performance in hedgerows across temperate Europe

“…Yet, due to their linear structure, hedgerows are generally characterised by a reduced habitat quality for many understorey forest herbs owing to edge effects, e.g. high soil nutrient levels combined with high light levels and less buffered microclimates, stimulating the growth of highly competitive ruderal species at the expense of typical forest herbs (Roy and de Blois, 2008; Wehling and Diekmann, 2008; Vanneste et al ., 2020a). These deteriorated conditions compared to forest habitats could further aggravate the risk of local extinction in hedgerows, because long‐term persistence is potentially hampered for forest herb species that have colonised these wooded linear structures (see Schmucki & de Blois, 2009).…”

Turning old foes into new allies – harnessing drainage canals for biodiversity conservation in desiccated novel ecosystems

“…Besides the local and landscape-level effects of canals on biodiversity, they may have consequences on even larger spatial scales. Canals often form continuous networks, overarching large regions and connecting isolated habitat fragments, similar to other linear landscape elements such as road verges and hedgerows (Vanniste et al, 2020). Canals, if longitudinally permeable for native species, can act as green corridors of dispersal, increasing regional connectivity and alleviating deficiencies of meta-population dynamics (van Geert et al, 2010; van Dijk et al, 2013), or can even act as conduits of climate change mediated range shifts, which would otherwise be hindered by extensive hostile areas, such as arable lands or exotic tree plantations (Saura et al, 2014; Robillard et al, 2015).…”