From the State of our Watersheds report: Forest cover on the Olympic Peninsula
In the recent State of Our Watersheds Report, the Jamestown Tribe documented a decrease in forest cover on the Olympic Peninsula. The animation below illustrates the decrease and the impact it could have on salmon.
From the report itself:
A minimum of 65% forested land cover is needed to prevent severe stream degradation. Four basins in the Focus Area were below this threshold in 2006, including the Dungeness Valley (DV) at 43.8%. While some forest cover is regained through plantings in working forests, much more is lost as forestland is developed. Three basins lost 4 to 10% of their forest cover from 1992 to 2006, the most being the Siebert McDonald basin (SM) at 9.5%.
Forested land cover is a vital component to the health of stream ecosystems at the watershed and riparian corridor scale (Stewart et al, 2001). The Hood Canal and Eastern Strait of Juan de Fuca Summer Chum Salmon Recovery Plan (HCCC, 2005) states that the “removal and modification of native riparian forests increases water temperatures, reduces stability of floodplain landforms, and reduces large woody debris recruitment to stream channels.” Loss of forested land cover causes degradation to aquatic systems even when the level of impervious surface is low (Booth et al, 2002). The threshold for minimal to severe stream degradation is 65% forest cover (Booth et al, 2002); however, any level of disturbance has an impact on stream biology (Morley, 2000). Restoring forest cover through riparian and riparian-adjacent vegetation planting is a vital element in the restoration efforts of salmon habitat in the Dungeness River (DRRWG, 1997).