DESCRIPTION
This project will continue to prevent and control invasive knotweed, Scotch broom, reed canary grass and herb Robert on 30 miles of the Hoh River's dynamic floodplain in Jefferson County; from the Olympic National Park boundary downstream to the river's mouth at the Pacific Ocean. When allowed to take over native habitats, these invasive species interfere with natural plant succession along the river banks, reducing the habitats, structures, shade, nutrients and bugs that support Hoh River wild Chinook and coho salmon, steelhead, bull trout and all other species that use riparian forests. All other restoration investments can be reversed by these aggressive species; once established, they are difficult and expensive to eradicate. After 13 years of successful treatment, knotweed has been reduced to a very sparse population; only 125 sites were mapped and treated in 2014, with 65% being single-stemmed plants under 3 feet tall. Because new plants grow from stem nodes and root fragments, much less is available to move to new locations. Reed canary grass, which fills wetlands, side channels and shallows at the edges of the river is in the beginning stages of invasion. Seed collection is a key part of the prevention and control protocol. In 2014, 317 RCG sites were located, de-seeded and treated.
The wild Hoh River on Washington’s Olympic Peninsula is home to native Chinook, coho, and steelhead, along with local cutthroat trout and bull trout. Bull trout is the only species listed as threatened. A high proportion of the river's riparian forest and floodplain is undeveloped, and glacial melt provides colder water refugia in summer months. The resiliency of native forests combined with glacial melt sustains these native stocks.
This project was successfully implemented in 2017 and 2018, with cycles of invasive species surveys and treatment completed on much of the 36.5 miles of the Hoh River mainstem, floodplain and several tributaries. Surveys and treatment and were conducted by foot and boat, and repeated treatments were applied to re-growth from seed banks. The sponsor located, mapped, and treated 862 invasive species sites in 2017 and 1,215 sites in 2018. Combining survey and treatment actions into a single effort, the early detection rapid response technique resulted in a total of 76 river miles were surveyed with 18 miles of treatment area. This resulted in over 3,000 acres of survey area and 1,215 acres treated for invasive species.
As planned, the sponsor distributed seed in selected sites. The sponsor also learned procedures and collected seeds of desirable native forbs and grasses for ‘seed increase’ in 2017. Unfortunately, disruptions in pass-through of state funding affected project planning, staffing, and field capacity. As a result, momentum on the native plant seed collection and increase and revegetation plan stalled when we lost the staff hired specifically to guide it, and were not able to rehire and continue in 2018. Other native plant partners were also affected by federal and state budget and hiring freezes (ONF, ONP, Clallam County), and thus, our connections to larger collaborative projects on the Olympic Peninsula were stalled. These issues resulted in a smaller treatment area than originally planned.
The project’s goal is to protect and maintain a disturbance-resilient riparian forest from early successional to mature stages and back again. This is achieved through repeated and targeted prevention and control activities targeting invasive plant species. These species all simplify native forest communities, replacing critical processes and functions provided by native plants throughout the ecosystem, with endless expansion without natural enemies or other controls.
With the evolution of inclusion of species other than knotweed, the sponsor was able to conduct control and prevention actions for non-native species that quickly and repeatedly respond to openings created by the elimination of another species.
