Umpqua Sugar Pine site in the Experimental Network for Assisted Migration and Establishment Silviculture (ENAMES)

Sugar Pine 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: USDA Forest Service.

Location: Umpqua National Forest, Tiller Ranger District.

Nearest town: Tiller, Oregon.

Species: Sugar pine (Pinus lambertiana.)

Site history: The site was part of the 2018 Columbus Fire, which burned more than 11,000 acres of the Tiller Ranger District in the Umpqua National Forest. The fire, which was part of the larger South Umpqua Complex/Miles Fire, burned with mixed severity. At least 10 percent of the area, including this site with legacy stands of sugar pine, burned in high-severity patches where nearly all the trees were killed. 

Before it was selected as a research area, the site was planned for an operational planting of about 80 percent Douglas-fir (Pseudotsuga menziesii), with minor components of sugar pine and ponderosa pine (Pinus ponderosa), as sugar pine rarely grows in pure stands.

Site characteristics: The site is at an elevation of 4000 ft and faces NW, with a gentle slope of 5-10°. The mean annual temperature is 47 °F (coldest month 34 °F, warmest month 64 °F) and mean annual precipitation is 1377 mm (131 mm as snow).

Planting date: Spring 2022 (immediately after snowmel.t)

Contact person:

Scott Kolpak, Southwest Oregon Area Geneticist, USDA Forest Service.

Robert Slesak, Research Forester, USDA Forest Service, Pacific Northwest Research Station.

Sugar Pine general site conditions: Dead overstory with interspersed slash and a slowly regenerating understory. USDA Forest Service photo.  

Management objectives and other considerations: Sugar pine is an important species in mixed-conifer forests. It contributes to the development of complex structure and wildlife habitat. Sugar pine is susceptible to several threats, including white pine blister rust, several bark beetle species, and increased fire severity resulting from a legacy of fire suppression. Long-term retention of the species is a key goal within its range and represents the primary value for the site.

Additionally, this site was planted as a research site. Our research objective is to compare the performance of four sugar pine seed sources over at least 15 years. The planting time, density, and site preparation was intended to reflect typical operational practices.

Site preparation: None. Seedlings were planted interspersed with slash and other regenerating vegetation.

Pre-planting site conditions: The burned with high severity in 2018. There was little regrowth by 2022. No salvage harvest occurred after the fire, so large downed logs and debris cover a large portion of the site.

Experimental design: The experimental design in this site is a randomized complete block with five replications per treatment applied to 1-acre plots.

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

Historical, early-century and late-century seed sources were collected from the National Forest System’s Pacific Northwest Region (Region 6) seed orchards using genetic stock bred for white pine blister rust resistance at the Dorena Genetic Resource Center and grown at the J. Herbert Stone Nursery in the Pacific Northwest Region. The late-century seed source was sourced from the Placerville Nursery in the Pacific Southwest Region (Region 5).

Seed source locations matching historical and predicted future climates for the Sugar Pine site. Map by Laura Gonzalez Mantecon.

Silvicultural treatment(s): The team is considering applying a release treatment to control competition from hardwoods as a management intervention. However, there are challenges with implementing release treatments on Forest Service land, so details of this treatment have yet to be determined.

Planting density: Operational contract crews planted 200 trees per acre.

Seedling stock type: Containerized.

Monitoring: The team will periodically monitor the site to track and compare seedling survival and growth. We will also monitor the presence and severity of white pine blister rust infection among seed sources. We took initial measurements in the first year after planting, with follow-up measurements planned for 5-, 10-, and 15-years post-planting.

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

A planted seedling in the ENAMES Umpqua Sugar Pine site. USDA Forest Service photo.

Forestry Technician Daniel Garcia measures a planted seedling at the Sugar Pine site. Photo by Laura Gonzalez Mantecon.

Challenges and opportunities: Several challenges arose during the establishment of this site. The initial site selected on the North Umpqua Ranger District experienced a rain-on-snow event in January 2022, leading to landslides that washed out access to the site just months before planting. The site that was eventually planted is on the Tiller Ranger District, about 25 miles south of the original site.

For most species, moving a site this distance would have delayed the project for several years because the seed sources needed to represent those adapted to the historical, early-, mid-, and late-century climate would have been different. Fortunately, sugar pine has much larger seed zones than many other conifer species in the Northwest, and the selected seed sources grown for the original site were still climatically appropriate for the new site.

The planted site experienced a late snowfall event in April 2022, which delayed planting. The snow caused some logistical challenges, including difficulty retaining a planting crew and coordinating personnel from Region 6 to oversee that the planting was done according to the experimental design.

However, the extra time before planting also resulted in an unexpected benefit. Initially, the planting only included three seed sources, as seed sources adapted to the late-century climate scenario are not present in Region 6. The planting delay provided time to locate seedlings representing the late-century seed source from the Placerville Nursery in California (Region 5).

Trial assessments, results, and lessons learned: Visual inspection in the months after planting suggested that initial seedling mortality would be high, although the cause of this mortality is currently unclear.

The 1-year, post-planting site visit in spring 2023 found a regenerating understory that includes trailing blackberry, Ribes, and rhododendron, as well as unevenly dispersed natural regeneration of Douglas-fir and sugar pine in parts of the site, with minor Western red-cedar and true fir components. The team also collected detailed survival and growth measurements of planted seedlings, which seemed to confirm low survival rates for all seed sources. 

Figure 1. Seedling survival for the different seed sources one year post-planting at the Sugar Pine site.

Figure 2. Seedling diameter by seed source one year post-planting at the Sugar Pine site.

Figure 3. Seedling growth by seed source one year post-planting at the Sugar Pine site.

Forestry technicians taking measurements of the Sugar Pine site one year post-planting. Photo by Laura Gonzalez Mantecon.

Downed wood and regenerating shrubs at the Sugar Pine site one year post-planting. Photo by Laura Gonzalez Mantecon.