Large Woody Debris a. Technical overview: riparian influence on large woody debris function Forested riparian areas are a significant source of large woody debris (LWD) in freshwater systems (Xxxxxx et al. 1986; Xxxxxx et al. 1988; Xxxxx and Xxxxxx 1998; Hyatt and Xxxxxx 2001). In marine environments, LWD (also known as ‘driftwood’) originates from both freshwater and marine riparian sources. Marine riparian areas contribute LWD to shorelines through natural recruitment processes, including windstorms, fires, wave action, and landslides (NRC 1996). Most of Puget Sound’s bluffs are naturally unstable and landslides are a common occurrence throughout the region (Xxxxxxxxxxx and XxxXxxxxx 2007). Large woody debris provides numerous benefits to shorelines and riparian areas including: • Moderation of local water temperature and soil moisture; • Accumulation of detritus serving as a food source and habitat for invertebrates; • Support of terrestrial vegetation (such as nurse logs); • Structural complexity that provides habitat for fish and wildlife; • Sediment trapping and bank erosion control. Recent research in the Puget Sound region has shown that marine LWD serves similar functions including provision of structural complexity; moderation of local water and soil temperatures; and habitat creation. An overview of the marine research by topic area follows.
Large Woody Debris. Agricultural activities within riparian areas have resulted in a loss of native vegetation and large woody debris, bank instability, and loss of flood-plain function (Xxxxxx et al. 1996).
Large Woody Debris. Large old-growth trees within marine riparian areas were historically among the first harvested in the region because of their close proximity to water and low transport costs (Xxxxxx 2006; Xxxxxxx 2007; Xxxxxx and Xxxxx undated). Along Puget Sound shorelines and rivers, the number, size and species composition of trees has changed dramatically since the mid 1800s due to tree harvest, levee construction, development and invasive species colonization (Xxxxxx et al. 1996; Xxxxxxx et al. 2002; Xxxxxxx 2007). As a result, the composition and volume of LWD on beaches has changed, with larger, mature logs occurring with less frequency. In a survey of 3.9 kilometers of beaches in north Puget Sound, fewer than 5 percent of large logs documented were considered ‘new’ recruits to the beach. The remaining 95 percent were severely weathered, and carbon dating revealed that many were delivered to the aquatic environment between 1700 and 1920 (Tonnes 2008). The amount of new wood, especially large logs, delivered to beaches appears to be declining (Gonor et al. 1988; Xxxxx and Xxxxxx 1994; XxxXxxxxx 2005; Tonnes 2008), Old growth logs are decomposing and gradually disappearing from beaches. In addition, much of the wood currently being recruited to beaches consists of end-cut logs, which are more mobile (due to their smaller size and lack of a root wad and branches) and therefore provide somewhat different functions over shorter temporal and spatial scales (Tonnes 2008).
Large Woody Debris. SPU has a large remaining commitment to replacing large woody debris (LWD) in watershed streams. This activity is an example where SPU can apply lessons learned from past projects to assure that new LWD is replaced efficiently for greatest ecological effect. Given the widespread use of LWD for habitat restoration in the Pacific Northwest, it may be of value to make sure projects reflect the current state of knowledge about LWD and its ecological value, and to consider whether projections of more extreme flow events in winter could alter the design of LWD projects, especially in mainstem reaches.
Large Woody Debris. The Permittee will allow investigations and will participate in design and placement of instream structures including large woody debris (LWD) structures, off-channel habitat and developing existing oxbows. The Pemitttee is willing to allow development of back-water rearing areas, if feasible, in this stretch of the Shasta River as long as liabilities and impacts to ranching are not elevated. If actual projects are developed, the Permittee will provide trees and on-site rock. -The Permittee is willing to re-work one specific bank erosion site that is just upstream of the Novy, Rice, Xxxxxx Diversion. At this site, a log jam would be incorporated in addition to adding LWD, as funding is available. This action will stabilize the bank and reduce sedimentation while increasing habitat complexity. Permittee will provide trees and on-site rock. It is anticipated that a grant application for these LWD projects will be submitted within the first year after signing the Template Safe Harbor Agreement. The estimated timeframe for implementation of LWD features is between 3-6 years after signing the Agreement
Large Woody Debris
