Riparian plant community composition and dissolved organic carbon characteristics interact to influence the role of terrestrial organic matter in boreal streams

Riparian plant litter input to forest streams is an important resource to microbial communities, supporting stream ecosystem functioning.

However, in boreal streams, dissolved organic matter (DOC) originating from terrestrial runoff and mires is often a highly available alternative resource.

The availability and quality of these resources are being altered by land use and climate change, but consequences for boreal stream functioning are still not well known.

Thus, in this project we will investigate how alterations to these terrestrial inputs influence microbial resource use and, thus, in-stream carbon (C) cycling. Our overarching goal is thereby to understand how land use and climate change influence boreal stream functioning.

To fulfill this goal, we will use a combination of controlled experiments, field studies, and a field survey, and investigate how the quality, timing, and mixing of riparian plant litter input influence its role as a resource to stream microbial communities, and how DOC interacts with these litter characteristics to alter this role.

Further, we will use various techniques to quantify resource quality, microbial use of the different resources, and which aspects of plant litter, DOC, and the microbial community are responsible for obtained results.

Such a broad and mechanistic approach will increase our chances to obtain knowledge that will be highly valuable for protecting the future functioning of boreal streams and to safeguard our water resources.