The landscape drives the stream Unraveling ecological mechanisms to improve restoration

The influence of surrounding land use on stream ecosystems is scale‐dependent, whereby instream habitat structure and organic matter inputs are determined primarily by local conditions such as vegetation cover, whereas nutrient supply, sediment input, hydrology and channel characteristics are influenced by regional conditions, including landscape features and land use types at some distance upstream and lateral to each specific site. Yet, the underlying mechanisms linking adverse in stream ecological effects to stream valley land use are still not fully understood. The aim of this thesis was therefore to unravel the mechanisms by which land use affects structure and functioning of lowland stream ecosystems. To this end, 1- 40 years of stream restoration practices by assessing the influence of policy goals on stream restoration efforts, the biophysical restoration objectives, the restoration measures, the scale on which these measures were applied, and the accompanying monitoring efforts was evaluated; 2- the mechanisms by which terrestrial runoff affects sediment composition and macroinvertebrate community composition in deposition zones of lowland stream ecosystems was unraveled; 3- lowland stream sediment characteristics in terms of food resources and habitat structure are land use specific and if they shape macroinvertebrate communities was determined; 3- the impact of catchment land use on the structure and functioning of lowland stream ecosystems was assessed; 4- the success of stream restoration projects, consisting of the addition of sand to the stream channel in combination with the introduction of coarse woody debris, to restore sandy‐bottom lowland streams degraded by channelization was evaluated.