Restoration Treatments

There are four general approaches for restoring whitebark pine forests in areas of suitable habitat where existing forests have been damaged or destroyed:

  1. Collect seeds and grow seedlings in a nursery, then outplant. This is the most costly restoration approach but also has the highest probability of success. Ideally seedling stock will be genetically resistant to white pine blister rust and appropriate for a warming climate. Works best in recently burned areas but may also work in clearcuts or mountain pine beetle-killed forests.
  2. Collect seeds and cache seeds directly into the soil. This approach is less costly than using nursery stock but germination, survival and early growth rates are much lower than for nursery-grown stock. As above, seeds should be from climatically suitable stock that is resistant to blister rust. Works best in recently burned areas, but may also work in clearcuts.
  3. Release and protect naturally regenerated seedlings from competing vegetation and other damaging agents. This typically involves removing faster-growing trees such as lodgepole pine, subalpine fir, and shrubby vegetation from areas where mature trees were killed by mountain pine beetle. Experience in the United States suggests that only about 20% of the seedlings are likely to grow well following release.
  4. Conduct prescribed burns to prepare sites for natural regeneration (by Clark’s Nutcrackers) or by artificial planting (1) or seeding (2), above. Prescribed burning requires plenty of advance planning and skilled personnel. Relying on natural regeneration is unlikely to be successful in northern BC where good cone crops and Clark’s Nutcrackers are scarce.
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Seedlings grown at UNBC April 2011

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Direct seeding success Wetzin'Kwa High elevation Sept 2012

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Weeding needed Gosnell June 2012

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Low severity burn creates seed beds Gosnell Joshua Rd site 2010

The Bulkley Valley Research Centre has begun to implement planting, seeding, and release of natural regeneration but has no plans to conduct prescribed burns for whitebark pine restoration at this time as there are plenty of recent wildfires and cutblocks in our area.

Planted Seedlings

Our restoration efforts have focused on spring planting of whitebark pine seedlings grown from seeds collected in the region from local parent trees that show evidence of resistance to white pine blister rust. As of 2018, we had planted at 14 sites across north central BC, totaling approximately 35 ha.

Through these efforts we have learned a great deal about successful early establishment of whitebark pine seedlings. In the Skeena Region (unlike regions with drier climate), unless planting in the alpine, it is important to select exposed, submesic and drier planting sites that will have minimal competition from brush and other tree species to achieve free-growing seedlings without repeated, costly brushing treatments. Nursery-grown seedlings survive well on such sites if planted as soon as possible after snowmelt when soils are still moist. We have little experience with summer and fall planting –but these seasons are likely to be riskier.

Growth of nursery-grown seedlings is very slow, but much faster than growth from seed (see below).

Recently our efforts have shifted to assisting partners in industry and government to assume responsibility for operational-scale planting of whitebark pine. Some adjustments to the nursery and planting regimes will be required to to reduce costs and to coordinate whitebark pine planting in forest cutblocks with the planting of commercial tree species.

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Gosnell one year after planting

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Courtney Brendan Sybille Heaussler planting Gosnell Trial 2011

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Alana planting Gosnell Trial

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Gosnell wildfire Crystal Rd site 2nd growing season 2012

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Wetzin'Kwa low elevation planting June 2012

Planting in Burn Pile Scars

Our restoration trials have shown that whitebark pine grows particularly well in recently burned soils due to lack of plant competition and the flush of mineral nutrients released by the fire. We recently established two small trials near Smithers to test the success of planting whitebark pine in the severely burned patches left behind after burning piles of logging slash at roadside (burn pile scars).

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planting whitebark pine in a roadside burn pile scar –unburned clearcut at rear.

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Healthy seedling growing in a burn pile scar.

There are several potential advantages of using burn pile scars to mimic favorable wildfire habitats:

  • rapid early nutrient release from burned organic matter should kick-start growth
  • reduced plant competition may allow for sustained growth even on mesic sites
  • burn pile scars can be easily reserved for whitebark pine if planting cannot occur at the same time as planting of commercial tree species
  • whitebark pine seedlings can be easily relocated and monitored over time

Potential disadvantages:

  • exposed, blackened and hydrophobic soils may cause heat, drought or frost damage
  • incinerated soils may be nutrient-deficient
  • soils may lack compatible mycorrhizal fungi
  • edges of burn piles often develop thick brush competition (raspberry, elderberry, fireweed)
  • burn pile scars may be located in unsuitable sites (avoid subhygric and wetter sites)

Direct Seeding

Direct sowing of whitebark pine seeds on to recently burned or mechanically disturbed seedbeds is a cheaper alternative to planting. Because whitebark pine seeds are so large they can have high rates of germination success, but their large size and high oil content also makes them extremely susceptible to being eaten before they have a chance to germinate.

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Seed germination March 2012

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Seed germination

The Bulkley Valley Research Centre established 2 direct seeding trials in the Gosnell wildfire and a third trial on Hudson Bay Mountain in 2011 (total of 560 seeds sown). We have also regularly examined a direct seeding trial established by UBC on Hudson Bay Mountain in 2007.

Germination rates of good quality seeds unprotected from predators was approximately 20 percent. Fifty five percent of the germinants survived for 5 years – higher than rates observed for most other tree species in direct seeding studies. The most common causes of mortality were drought, unidentified pathogens, soil erosion and crushing under falling debris (eg bark sloughing from burned trees). The 5-year establishment rate was thus 11 percent of the total seeds sown.

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Direct Seeding Crystal Road site June 2012

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Largest direct-sown seedlings, Gosnell wildfire, Sept 2015.

Growth of direct-sown seed was much slower than that of planted seedlings. Seedlings were 1-2 cm tall at 1 year and most seedlings continued to grow very slowly, averaging 6 cm in height and 1 mm in stem diameter after 5 growing seasons. The tallest seedlings on a forest site (~1000 m elevation) were 20 cm tall at 5 years. Seedlings in the UBC trial, located at timberline (1600 m elevation), were typically ~10 cm tall at 10 years, with the tallest seedlings reaching ~30 cm at 10 years.

After 7 years of monitoring the success of directly sown whitebark pine seeds, we have concluded that although this approach can be moderately successful, it is not an efficient use of whitebark pine seeds. Germination rates are too low and subsequent growth is too slow to warrant widespread use of this technique in the Skeena Region where high quality whitebark pine seeds are difficult and expensive to procure.

Direct seeding may be a useful supplement to planting of rust-resistant nursery stock if large quantities of seeds of unknown quality were collected from parent trees that were not carefully examined for evidence of blister rust. In such cases it would not be worthwhile to grow nursery seedlings from the dubious seeds. Such a scenario might occur, for example, during an unusual mast crop year when crews unskilled workers or volunteers are available to collect abundant cones from low-hanging branches, or during the scheduled destruction of a whitebark pine stand for a mine, ski resort, communication tower or other development.