Forested buffers in agricultural landscapes : mitigation effects on stream–riparian meta-ecosystems

Stream–riparian meta-ecosystems are strongly connected through exchanges ofenergy, material and organisms. Land use can disrupt ecological connectivity byaffecting community composition directly and/or indirectly by altering the instreamand riparian habitats that support biological structure and function. Althoughforested riparian buffers are increasingly used as a management intervention, ourunderstanding of their effects on the functioning of stream–riparian metaecosystemsis limited. This study assessed patterns in the longitudinal and lateralprofiles of streams in modified landscapes across Europe and Sweden using a pairedreachapproach, with upstream unbuffered reaches lacking woody riparianvegetation and with downstream reaches having well-developed forested buffers.The presence of buffers was positively associated with stream ecological status aswell as important attributes, which included instream shading and the provision ofsuitable habitats for instream and riparian communities, thus supporting moreaquatic insects (especially EPT taxa). Emergence of aquatic insects is particularlyimportant because they mediate reciprocal flows of subsidies into terrestrial systems.Results of fatty acid analysis and prey DNA from spiders further supported theimportance of buffers in providing more aquatic-derived quality food (i.e. essentialfatty acids) for riparian spiders. Findings presented in this thesis show that bufferscontribute to the strengthening of cross-ecosystem connectivity and have thepotential to affect a wide range of consumers in modified landscapes.