Managing green infrastructures

The term green infrastructure addresses the spatial structure of anthropogenic, semi-natural and natural areas, as well as other environmental features which enable society to benefit from ecosystems’ multiple services. Focusing on two green infrastructures, anthropogenic wet meadows and natural forest successions, this thesis applies a macro-ecological approach based on comparisons of multiple landscapes as complex social-ecological systems. Firstly, the trophic interactions of avian predation in anthropogenic wet meadows under different management regimes in southern Sweden were explored (Paper I). This study tested the hypothesis that the abundance of avian predators and predation is higher in rapidly declining vs. relatively stable wader populations. Secondly, the trophic interactions of large mammals in Europe’s boreal forest biome were explored (paper II). This study tested the hypotheses that reduced numbers of large carnivores and increased numbers of large herbivores affect the recruitment of both ecologically and economically valuable trees, and that forest management intensity is correlated to a reduction in tree recruitment. The results show, firstly, that the abundance of avian predators and predation was higher in rapidly declining wader populations. Secondly, reduced numbers of large carnivores and abundant large herbivore populations were correlated to reduced recruitment of focal tree species. There was no relationship with the index of forest management intensity. To conclude, this thesis illustrates the consequences of disturbed tropic interactions on two different green infrastructures (anthropogenic wet meadows and boreal forests). The governance and management of green infrastructures is thus complex, because both the quantity and quality of land cover, and trophic interactions, need to be considered. This thesis confirms the importance of studying the consequences of altered trophic interactions in multiple landscapes rather than in a single landscape or region alone. Macro-ecological studies comparing countries and regions with different contexts, e.g., landscape history, traditions, governance and management systems, can support the development of more holistic views on the planning and management of green infrastructures