Canadian Forest Service Publications

Feasting on terrestrial organic matter: Dining in a dark lake changes microbial decomposition. 2018. Fitch, A.; Orland, C.; Willer, D.; Emilson, E.J.S.; Tanentzap, A.J. Global Change Biology:

Year: 2018

Issued by: Great Lakes Forestry Centre

Catalog ID: 39335

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1111/gcb.14391

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Plain Language Summary

Boreal lakes are major contributors to the global carbon cycle, partly because of break down of forest-derived organic matter (forest OM). The ability for bacteria to break down and alter forest OM may depend on environmental characteristics and community composition. However, the connection between these two potential drivers of decomposition is poorly understood. We tested how bacterial activity changed along experimental gradients in the quality and quantity of forest OM in two small boreal lakes: one with dark water from forest carbon, and another clear lake with little forest carbon. We found that bacterial production and activity differed between the two lakes because of resident bacterial communities that were differently adapted to utilize forest OM. The result was that in the dark lake, carbon was funnelled into bacterial biomass, whereas in the clear lake, carbon was emitted as carbon dioxide (greenhouse gas).Our results suggest that changes in forest OM inputs to lakes will have different effects on carbon cycling depending on the potential for photo-degradation of OM and composition of resident bacterial communities. This has implications on forest management with carbon management in mind, such that the conditions of the receiving water (lake, stream) should be considered in management approaches. This also suggests that changes in forest OM inputs related to climate change will have a different response the conditions of the receiving water.