Rain or shine, the work on the Preserve continues! From November 17th to 25th, a Washington Conservation Corps (WCC) crew was on the ground in Hidden Valley where they completed an amazing amount of work in just six days.
The crew removed invasive Himalayan blackberry (Rubus bifrons) and Evergreen blackberry (R. laciniatus) throughout the valley. They achieved this by pruning back blackberry canes where needed to improve accessibility to root crowns, then roots were grubbed out using steel-handled shovels, “Wolverines,” and smaller digging tools.
Over the six-day period, the WCC crew completed the following work:
- 22 cubic yards of mulch applied
- 39,780 square feet of area cleared of invasive plants
- 3,960 linear feet of trails and paths surveyed, brushed and/or constructed
This work was completed to reduce invasive plant competition with native plants growing in the Preserve and reduce sources of propagule pressure on other areas without established invasive plants. All invasive plant material, including the root crowns, were consolidated into three piles to dry out and compost on site for further mulching.
The crew also spread mulch around previously installed trees and shrubs to improve moisture retention and reduce weed growth and competition near recent plantings. The crew prioritized conifers, Garry Oak (Quercus garryana), and then shrubs for mulching.
Lastly, the crew removed plant material and debris obstructing or growing into Big Tree Trail using loppers, pruners, and rakes. This was done to maintain safe and easy public access to the trail.
This work is in preparation for future work that the WCC will do next time they are onsite:
- Blackberry removal to prevent reestablishment in Hidden Valley.
- Mulching to help prevent invasive plant regrowth and protect new plant establishment.
- Trail maintenance to prevent plant regrowth onto the trails that push people to move off the trail and onto areas not meant for foot traffic.
- Trail repair to improve the surface in the upper sections of Big Tree Trail that have areas of exposed tree roots.
The WCC crew is scheduled to return to the Preserve for additional work during the last two weeks of June 2026. We value our relationship with the WCC and are thankful for all of their work at the Preserve.
– Jeff Wirtz, Vice President