CONTROLS ON AUTOTROPHIC RESPIRATION, HETEROTROPHIC RESPIRATION, AND DECOMPOSITION IN NORTHERN FORESTED RIVERS

Abstract

Autotrophic respiration (AR), heterotrophic respiration (HR), and decomposition are important contributors to the carbon cycle in streams. It is important to understand how different environmental factors, such as canopy cover and dissolved organic carbon (DOC), influence these processes. DOC concentrations in northern forested streams are increasing, which may affect light and carbon availability. To examine the effects of DOC and canopy cover on these processes we measured gross primary production, ecosystem respiration and decomposition at 8 sites in 4 streams in the Upper Peninsula of Michigan and used quantile regression to estimate AR and HR. Among sites, AR and decomposition showed no relationship with canopy cover using Spearman’s correlation (p = 0.33), while neither respiration process nor decomposition showed a relationship with DOC concentrations (p = 0.75). The results do indicate potential regional and temporal variation in AR and HR; however the quantile regression approach is insufficient to examine this.