Pettijohn site in the Experimental Network for Assisted Migration and Establishment Silviculture (ENAMES)
The Pettijohn site, part of the Experimental Network for Assisted Migration and Establishment Silviculture (ENAMES) study, has been established on Washington Department of Natural Resources land in northeast Washington to test assisted population migration of ponderosa pine using four seed sources that match historical and predicted future climates at the site, as well as the effects of different seedling stock types on seedling establishment and growth. The site burned during the 2021 Walker Creek Fire and will be planted in the spring of 2024.
Pettijohn site 3D map showing experimental plots color-coded by the climate scenario each seed source is adapted to. Map by Laura Gonzalez Mantecon.
Land manager: Washington Department of Natural Resources.
Nearest town: Tonasket, WA.
Species: Ponderosa pine (Pinus ponderosa).
Site characteristics: The site is on a 5- to 15- percent, south-southeast slope at 4,150 ft of elevation. The soils are soft and shallow ashy loamy andisols derived from volcanic ash over glacial till, with exposed rocky slabs. The mean annual temperature is 40 °F (coldest month: 19 °F, warmest month: 60 °F,) and mean annual precipitation is 489 mm (206 mm of which is snow.)
Site history: The first recorded entry into this parcel was a variable density thinning in 1993 as part of the 4 Forties timber sale, followed by a fuels reduction treatment in 2014 and a shelterwood removal treatment in 2021 that left healthy ponderosa pine, western larch, and Douglas-fir. The site then burned with high intensity in the 2021 Walker Creek Fire.
Planting date: Spring 2024.
Contact person:
Sam Steinshouer, State Lands Forest Health Program Manager; Washington Department of Natural Resources.
Joseph Hoagland, Silviculture Forester; Washington Department of Natural Resources.
Robert Slesak, Research Forester; USDA Forest Service, Pacific Northwest Research Station.
Pre-planting site conditions at the Pettijohn site. Photo by Erin Baumgart.
Management objectives and other considerations: Management goals for this site include re-establishing trees for future timber production, in addition to the research goals of testing seed source performances and vegetation control effects on seedling establishment and growth.
Site preparation: Baseline herbicide spray 1 year before planting.
Pre-planting site conditions: The site has some dead overstory trees. The very sparse vegetation that survived the spray treatment includes fireweed and saskatoon, as well as a very small amount of natural pine regeneration.
Experimental design: The experimental design in this site is a randomized complete block with four replications per treatment applied to 0.5-ac plots.
Assisted migration treatments: The team used the Seedlot Selection Tool to choose four planted seed sources (see table below).
Climate period
| Seed origin | Seed source elevation (ft) | Mean cold month temperature (°C) | Summer heat-moisture index |
Historical/local (1961-1990) | Okanogan National Forest | 4,000–5,000 | -7.27 | 80.0 |
Early-century (2011-2040) | Wenatchee National Forest | 2,500–3,000 | -5.80 | 117.6 |
Mid-century (2041-2070) | Wallowa-Whitman National Forest | 4,000–4,500 | -4.07 | 123.5 |
Late-century (2017-2100) | Wallowa-Whitman National Forest | 4,000–4,500 | -2.25 | 98.8 |
Seed source locations matching historical and predicted future climates for the Pettijohn site. Map by Laura Gonzalez Mantecon.
Silvicultural treatments: Three different seedling stock types (see below).
Seedling stock type: Containerized (styro 5/6, styro 10, ellepot).
Planting density: Operational contract crews are planting 300 trees per acre.
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.
Forestry technician Broderick DeAngelis delimits experimental plots using stakes and colored flagging tape to prepare the Pettijohn site for planting. Photo by James Dollins.
Figure 1. Seedling survival for the different seed sources one year post-planting at the Pettijohn site.
Figure 2. Seedling diameter by seed source one year post-planting at the Pettijohn site.
Figure 3. Seedling growth by seed source one year post-planting at the Pettijohn site.
Map
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https://research.fs.usda.gov/sites/default/files/2023-10/pettijohnlayout.pdfFile Type: pdf
File Size: 8.16MB
Project
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Project
https://research.fs.usda.gov/pnw/projects/enames