Human-derived effects and failure in management drive coastal urban foredune degradation and novel vegetation structure

Abstract

Urbanization can drive significant decay in species diversity and abundance; in dune ecosystems the composition changes at a pace with changes in spatial fragmentation. Infrastructure deployment and human activities may provoke synergistically a reduction in dune patch size and/or habitat loss and thus a potential for rapid establishment of exotic species, producing a ‘novel’ habitat configuration. In this study we examine the effects of coastal urbanization and associated human activities in foredune patch fragmentation and changes in floristic composition and abundance in an urban-rural gradient. Using samples from a recently bulldozed and managed urban foredune area, we assess the legacy of erroneous practices associated with planting of exotic species in urban settings. We found a significant increase in foredune fragmentation, estimated as the occurrence of marks left by vehicles (4WD, 2WD) and people in foredunes close to or within urban settings. A marked change from native to non-native plant species was found from rural to urban environments, with non-native species contributing to increase species richness in urban settings. A positive relationship of non-native species with level of foredunes fragmentation was found. Dominance of non-native species was persistent through time in altered foredune patches. Our findings showed that incorporation of non-native species for aesthetic or engineering purposes in bulldozed foredunes, could limit colonization of native species through rapid establishment and complete dominance of non-native ones. Historical activities associated with coastal infrastructure upgrades seem to configure the present foredune floristic pattern present in urbanized coasts. Management strategies correcting past erroneous actions and promoting foredune rehabilitation could help the conservation of services that these ‘novel’ habitats provide in coastal urban environments.