Keller Ridge site in the Experimental Network for Assisted Migration and Establishment Silviculture (ENAMES)

Management objectives and other considerations: This is a fairly productive site containing ash soils, so from a forestry standpoint it is desirable to get this stand on a path to produce timber again. While doing so, we will help anchor the soil and provide wildlife habitat as well.  The unit sits atop a major ridge at the headwaters of the Chuweah watershed, making it a particularly important location to curb potential erosion. The area is also considered prime ungulate habitat and is home to some of the largest elk herds in the Omak/Nespelem District of the Colville Reservation.

The combination of elevation, precipitation, and soil type make this study block a good candidate to test planting Western larch. Larch is a highly desirable species for planting following a disturbance for both economic and ecological reasons: First, it is a strong conifer competitor following a disturbance, and we wish to embolden this trait through artificial regeneration. Second, it is also highly fire tolerant, even in a non-merchantable plantation state, which helps us protect our planting investment.

Our recent post-planting survival counts indicate that Western larch has had the lowest survival rates out of all the species that we plant (larch, ponderosa pine, and Douglas-fir). Unlike ponderosa pine plantings, higher or lower survival did not seem to be tied to elevation or precipitation amounts that year. This seems to indicate that seedling size and type may play more of a role in Western larch artificial regeneration survival, which is why we chose to test seedling stock type for this site.

In general, Western larch is at the edge of its range on most of the Colville Reservation, a fact that is only going to be exacerbated by climate change.  Western larch is the poster child for needing help through assisted migration, and this study can hopefully provide a step in the right direction to help it remain on the landscape.

Site preparation: Excavator piling with a follow-up vegetation control treatment (mechanical or chemical, to be determined).

Pre-planting site conditions: There are scattered live overstory and pole-size ponderosa pine, Douglas-fir, and western larch trees across the block at a density of 3 trees per acre. The fire killed most planted seedlings; very few planted or natural seedlings are present. Grass has fully reoccupied the site and brush is starting to come back in the shallow draws.  

Experimental design: A randomized complete block with four replications per treatment applied to 0.5-acre plots.

Assisted migration treatments: The team used the Seedlot Selection Tool to choose four planted seed sources (see table below).

Seed source locations matching historical and predicted future climates for the Keller Ridge site. Map by Scout Dahms-May.

Silvicultural treatments: Three different stock types (see below).

Planting density: Operational contract crews will plant 300 trees per ac.

Seedling stock type: Containerized stock (Styro 6, Styro 10, Styro 2A [211A]).

Monitoring: The site will be monitored to track and compare seedling survival among seed sources and silvicultural treatments. Measurements are planned for 1, 5, 10, and 15 years after planting.

The site may also serve as a demonstration plot for managers to visit and visually compare seed source performance.