Talk Tradeoffs in multifunctionality of road verges and their delivery of ecosystem services

Road verges may contribute substantially to ecological functions and delivery of ecosystem goods and services in both urban and rural greenspaces. The function as habitat, dispersal corridor or stepping stone for both plants and animals, provision of pollen and nectar resources for pollinators, aesthetic aspects, noise reduction, trapping pollution, intercept runoff and manage stormwater are among the valued contributions. Road verges are however narrow, built on disturbed soils and with traffic having an impact on environment and mortality risks. Thus there are certain limitations and trade-offs between functions and services. Here I present results from a literature review on how establishment and management can be tailored to specific functions and services within the boundaries of road safety and management costs. I especially address how the interactions between soil, soil biota, vegetation and management can be used to maintain biodiversity based ecosystem services over time

The conflict between avoiding establishment of invasive species and promoting diverse vegetation is given special attention and referred to the potential use and limitations of assembly filters. A combination of abiotic and biotic filters can be used to reduce establishment of invasive species.

Biotic resistance to invasion can be increased by manipulating competition and plant-soil feedbacks. A rapid establishment of high density redundant vegetation composed of competitive species with overlapping niches, occupying available niches and rapidly closing open spaces usually is successful in preventing establishment of invasive species. Combined with abiotic filters like reduced availability of nutrients and water and maintenance of regular cutting, these measures usually are efficient in preventing establishment of invasive species from seed. This approach also strongly reduce the possibility to establish a diverse self-sustaining vegetation as it cuts of possibilities to regenerate from seeds and increase species turnover through competition. The challenge of combining these targets is further discussed, possible solutions presented and knowledge gaps identified.

road verge, ecosystem services, multifunctionality, biodiversity