A roadmap for sustaining biodiversity and ecosystem services through joint conservation and restoration of northern drainage basins

1. Freshwater ecosystems and their biota are more seriously threatened than their marine and terrestrial counterparts. A solution to halt increasing negative impacts of anthropogenic development would be to reconsider the basics of nature conservation (i.e. protection of pristine and near-pristine areas) and restoration (i.e. returning an impacted site to as natural condition as possible) through inclusion of the knowledge on abiotic and biotic dynamics of rivers draining pristine catchments. In boreal and Arctic regions, such comparisons are still possible because in addition to harbouring strongly modified drainage basins, some of the most natural drainage basins are also situated in these high-latitude areas. 2. A suitable approach for simultaneous planning of joint river conservation and restoration would be to (i) examine how well different kinds of rivers are covered by existing protected area networks and (ii) to restore parts of degraded rivers to facilitate colonization by aquatic and riparian organisms that have found havens in existing protected areas. This joint approach is a two-way road, as conservation and restoration benefit from each other by allowing river networks to facilitate movements of organisms and matter, thereby mimicking natural riverine meta-systems in anthropogenically modified drainage basins, with restored sites acting as stepping-stones between protected areas. 3. We argue that existing policy instruments should consider the fact that river ecosystems are spatially and temporally dynamic meta-systems. These characteristics should be given due attention in conservation and restoration rather than relying on a static approach where a snap-shot classification of river reaches is thought to be enough without considering underlying ecological dynamics. Taking ecological dynamics into account would contribute to sustainable management and maintenance of biodiversity and ecosystem services.