Understanding multiple stressors in northern stream ecosystems: The interactive effects of forestry and extreme hydrological events

Ongoing climate change and land-use represent severe pressures on northern stream ecosystems. In Sweden, extended drought periods and more intense flood events are increasingly more common. At the same time, small streams situated in production forests are under pressure from forestry.

Both of these anthropogenic pressures trigger many physicochemical changes, and when those changes exceed the range of background undisturbed conditions they become stressors for aquatic biota.

We currently lack an understanding of how stressors associated to extreme hydrological events and those associated to forestry interact to determine ecological responses in small streams. This project will provide novel insights in the multiple-stressor phenomena in Swedish streams.

We will apply a unique integrative approach that combines experimental manipulations in mesocosms and natural streams with existing and new data collected in streams in connection to extreme events.

In this 4-year project, we will break new ground by a) testing how aquatic organisms and ecosystem functions in small streams affected by forestry responded to and recovered from extreme drought and extreme flood events;  b) establishing a baseline for stream ecosystem responses to induced drought with subsequent re-wetting in the absence of forestry pressure, and c) assessing the impacts of combined forestry and extreme-hydrological stressors on a variety of biotic responses in an experimental setting.