Title: Flushed Away: Linking Carbon Storage and Log Jams in Colorado's Front Range

Historical documents and recent field studies suggest that resource use within the Colorado Rockies during the past two centuries has reduced the wood loads and frequency of wood jams along most forested streams. Recent research has also shown that streams play a significant role in the sequestration and transport of organic carbon, and wood jams are a key component of storage and biological processing in mountain headwater streams. Log jams tend to slow the transport of carbon and encourage its uptake in the riverine environment and therefore may have effects which extend beyond streams and into the global carbon cycle. The paper aims to quantify the effects of past and present resource management on instream wood loads and logjam frequency along Colorado's Front Range. We hypothesize that more highly impacted reaches (as measured by recent fire, logging, and high flow regulation) will demonstrate lower wood loads, lower jam densities and lower overall volume of stored sediment. In addition, we hypothesize that soils stored behind log jams will have a higher OM and TC content. If these hypothesis hold true, then by implication areas with younger forests and higher impacts will have higher carbon flux and lower return of carbon and nutrients to the surrounding ecosystem. Wood loads and jam frequency are compared based on stream characteristics, forest age, and flow alteration. In addition, sediment samples from reaches with and without log jams are compared based on organic matter (OM) content and Total Carbon (TC) content. Samples taken from behind log jams are compared to samples taken from other backwater areas along a river reach. Preliminary results of the 2010/2011 field seasons indicate that sediment samples taken from log jams (regardless of forest age) have an overall average of 5% OM, as compared to an average of 1% OM in samples taken from non-jam areas. Samples taken from log jams on streams draining old growth forests (more than 250 years since last disturbance) have an average of 12% OM.