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MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling

BiodivERsA: Understanding cross-habitat linkages between blue and green infrastructure (CROSSLINK) - Norway

Alternative title: Grøn-blå infrastruktur og artsmangfold i elver (CROSSLINK)

Awarded: NOK 3.6 mill.

CROSSLINK investigates how land and water interact in riverine ecosystems. Stream banks (riparian areas) are considered «green infrastructure», while the streams themselves are «blue infrastructures», together forming stream-riparian GBIs (green-blue infrastructures). GBIs are the core unit of analysis in CROSSLINK, as appropriate management of these can have significant benefits for overall biodiversity in the landscape. We conducted extensive novel field studies in four case-study basins differing in land-use in Norway, Sweden, Belgium and Romania in addition to analyzing existing data and policies on GBIs. Land-use will cover forestry, agriculture and urban areas, the latter being the focus in Norway with Oslo city as case. Overall, the CROSSLINK project has revealed multiple positive outcomes of woody riparian buffers. For example, woody riparian buffers can increase biodiversity of terrestrial and aquatic organisms, and lead to improved ecological status as assessed using standard EU Water Framework Directive indices. Woody riparian buffers enhance key regulating ecosystem services, by reducing temperatures, and especially dampening summer thermal extremes, and modulating the excessive growth of aquatic macrophytes. We further found general reductions in nutrient concentrations and deposition of mineral sediments associated with riparian buffers. Furthermore, woody riparian buffers help enhance key supporting ecosystem services underpinning C cycling and sequestration and increase transfer of high quality Omega 3 fatty acids to terrestrial organisms, representing a key nutrient of importance for vertebrates, including humans. However, occurrence of these outcomes was often dependent on the level of human impact in the catchment, and on the overall size and vegetation density of the buffers. In the Oslo case study, we found that positive effects of woody riparian buffers were abolished in rivers with a high urban impact. This was evident with regard to fish that were only sampled in the Norwegian case study. Fish density, mainly trout, responded positively to the presence of buffers in all but the most polluted rivers. Overall, our results will be incorporated into optimization models that are tools to predict strategies for GBIs that minimize their costs in terms of management or loss of land-use revenue, while maximizing their positive benefits from the individual stream reach to the entire riverine landscape.

CROSSLINK prosjektet viste at kantsoner har et stort potensial som naturbasert løsning (NBS) i forhold til biologisk mangfold og økosystem funksjon. Vi har jobbet med kantsoner som dekker ulike arealbruk fra skogbruk til jordbruk og urbane områder. For alle typer arealbruk hadde kantsoner en positiv effekt på tilstanden både i vann og på land. Både temperatur regulering og økt karbonoppmagasinering viser kantsoners potensiale i forhold til klimatiltak som, sammen med positive effekter på biologisk mangfold og økosystem funksjon, gjør at kantsoner kan bli en av de fremtidig løsninger på samfunnsutfordringene i relasjon til vann. Våre resultater viste også tydelig at etablering av kantsoner ikke nødvendigvis er nok. Effekten av kantsoner var best langs elver, der kun var lett til moderat forurenset. Våre resultater peger derfor også på at en helhetlig forvaltning av elver og deres kantsoner er nødvendig hvis ønsket er vesentlig forbedring av vannmiljøet.

CROSSLINK will analyse existing data and policies on stream-riparian GBI and conduct extensive novel and spatially explicit field studies in four case-study basins differing in land-use in Norway (forested and urban stream reaches in the Oslo Fjord basin), Sweden, Belgium and Romania. Stakeholders assist in identifying pressures and priorities, areas of conflict, and possible actions in management for each case-study system. Based on compilation of existing data and novel empirical field studies, a GBI asset portfolio will be constructed, comprising biodiversity, multiple supporting ecosystem processes (e.g. algal productivity, litter decomposition, soil bioturbation) and ecosystem services (e.g. nutrient retentivity, fish, water quality, C sequestration), and flood protection and resilience properties (functional redundancy, cross-scale connectivity). Three approaches to quantifying network connectivity are employed: (1) the probability of connectivity (PC) metric, which is based on drainage basin structure and topology and discontinuities (e.g. dams) (2) direct quantification of lateral connectivity based on polyunsaturated fatty acid and isotope markers and organism dispersal, and (3) identification of the spatial scales constraining activities and movements of species, based on discontinuity analysis of species and functional trait data for key organism groups (terrestrial and aquatic invertebrates, algae, aquatic microbes, fish). The explanatory power of these approaches is compared and contrasted, leading to identification and refinement of optimal connectivity measures at both local and whole network scales. Relationships between the portfolio elements and spatial connectivity and multiple human uses and impacts are analysed, and incorporated into optimisation models which focus on identifying spatial configurations and strategies for GBI that minimize trade-offs in management while maximizing multifunctionality from local to landscape scales.

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MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling