Beavers (Castor canadensis) are frequently referred to as ‘ecosystem engineers’ in part because of the profound influence their dams and associated networks of dens, side-channels and pools have on habitat heterogeneity and the complexity of the environments they occupy. Recently, beaver have been incorporated into stream restoration efforts to help reconnect incised streams to their floodplains and improve physical habitat for fish and other species of concern. Although these ecosystem engineers produce rich and complex habitats, they do not provide as-built drawings of their work and the dynamic habitats they construct are very difficult to survey and characterize for monitoring their effectiveness. Traditional ground-based topographic, vegetation and habitat surveys are often inadequate to properly characterize such habitats or detect change. Similarly, traditional remotely sensed data may lack the resolution and accuracy to detect important changes through time. To better understand the character and dynamics of these complex habitats created by beaver, we will present some data and new techniques for describing their structure using a hybrid ground-based and remote-sensing technology: ground-based LiDaR (a.k.a. terrestrial laser scanning - TLS). Specifically, we are seeking to use this data to explore the feedbacks between key components - beaver, riparian vegetation, channel complexity and their collective influence on salmonid habitat. The combination of high resolution and high accuracy 3D point clouds from TLS data provides new opportunities for characterizing physical habitat and detecting changes with repeat surveys. However, TLS also presents significant methodological challenges in how we manage and analyze data, which may be 2 to 5 orders of magnitude greater in size then traditional ground-based or remotely sensed data sets. Preliminary data and analyses from algorithms under on-going development will be presented. The data is from the first year of monitoring on Bridge Creek, an incised tributary to the lower John Day River in semi-arid central Oregon, is currently in the early stages of a long-term salmonid habitat restoration and monitoring effort. The restoration seeks to reconnect the incised channel to its former floodplain by promoting bed aggradation using beaver. This is accomplished by providing structural support (i.e. wood posts) and building materials (i.e. wood) at key locations to encourage beaver to build dams and establish sustainable colonies. The TLS data captures the system state and its complexity at snap-shots in time through the restoration process, and is used to highlight the potential and challenges associated with using the data as a change detection monitoring tool.
Available at: http://works.bepress.com/joseph_wheaton/109/