ABSTRACT
In the face of uncertainties around coastal management and climate change, coastal engineering interventions need to be able to adapt to changing conditions. Nature-based solutions and other non-traditional, integrated interventions are gaining traction. However, system-based views are not yet embedded into coastal management strategies. Moreover, the differences in coastal interventions, ranging from hard ('grey') to nature-based ('green') infrastructure remain understudied. In coastal management it is therefore challenging to work with the grey-green spectrum of interventions with clarity and focus, and to produce results that can be evaluated. The objective of this paper was to examine whether there is a common understanding of: the characteristics and differences between grey and green infrastructure, where interventions sit on this spectrum, and the resilience of grey versus green infrastructure. We conducted an integrative literature review of the grey-green spectrum of coastal infrastructure. We examined 105 coastal protection case studies and expanded the double-insurance framework to ensure an integrative approach, looking at both external and internal factors of resilience. Our review showed that external factors are typically used to characterise the grey-green spectrum. However, although useful, they do not facilitate a holistic comparison of alternative interventions. The additional consideration of internal factors (response diversity, multifunctionality, modularity and adaptive, participatory governance) bridges this gap. The review showed that dikes, reefs, saltmarshes, sand nourishment and dunes span a wider segment of the grey-green spectrum than they are generally categorised in. Furthermore, resilient solutions for adaptation are unlikely to be exclusively engineered or natural, but tend to be a mix of the two at different spatial scales (micro, meso, macro and mega). Our review therefore suggests that coastal planners benefit from a more diverse range of options when they consider the incorporation of grey and green interventions in the context of each spatial scale. We propose that internal resilience should be accounted for when infrastructure options are comparatively evaluated. This consideration brings attention to the ways in which the grey-hybrid-green spectrum of infrastructure enhances value for people.
ABSTRACT
Ecosystem service assessments rarely consider flows between distant regions. Hence, telecoupling effects such as conservation burdens in distant ecosystems are ignored. We identified service-providing species for two cultural ecosystem services (existence and bequest, and birdwatching) and two receiving, i.e. benefitting, regions (Germany, the Netherlands). We delineated and analysed sending, i.e. service-providing, regions on a global scale. The proportion of service-providing species with distant habitats was higher for birdwatching (Germany: 58.6%, Netherlands: 59.4%), than for existence and bequest (Germany: 49.3%, Netherlands: 57.1%). Hotspots of sending regions were predominantly situated in tropical and subtropical grasslands, savannas and shrublands and were significantly more threatened and poorer than the global mean. Hotspot protection levels for flows to Germany were higher than the global mean, and lower for the Dutch hotspots. Our findings increase understanding on how distant regions underpin ecosystem services and necessitate interregional assessment as well as conservation efforts.
