RESTORATION by Bob Keane

Fire is the keystone disturbance that shaped most whitebark pine landscapes, so treatments should be designed to emulate fire’s historic effects on the landscape (Keane and Arno 2001).  While prescribed fire is the obvious tool, mechanical cutting treatments can also be effective.  Properly designed silvicultural thinning can simulate the effect of non-lethal surface fire in whitebark stands (Keane and Arno 2001).  Treatment unit sizes and shapes should be similar to the patterns left by past fires and need to reflect the amount of available whitebark pine seed source in surrounding stands (Keane and Parsons 2008[in press]).  Do not design treatments that create large areas for whitebark pine regeneration if there is little seed available for caching unless planting rust-resistant seedlings is possible.

Whitebark pine is regenerated almost exclusively from Clark’s nutcracker seed caches. Therefore, restoration treatments that optimize regeneration are those that optimize conditions that attract Clark’s nutcracker caching.  The optimum caching habitat for the Clark’s nutcracker is recently burned over areas (birds may like the pattern created by the fire for remembering cache sites) greater than 50 meters diameter.  These were found to be attractive to Clark’s nutcrackers (Keane and Arno 2001; Tomback et al. 2001, Norment 1991).  Seedling survival of whitebark depends on open stand conditions for as much of the rotation as possible (whitebark pine is an early seral species, and is shade-intolerant).

Mechanical cuttings

There are basically two major types of restoration treatments that can be implemented at the stand level: prescribed burning and mechanical cuttings, or some combination of both.  Other minor treatments can be used to augment or compliment the two major treatment types.  Most restoration treatments are designed to eliminate or reduce competing species and increase the regeneration opportunities for natural-selection to produce white pine blister rust-resistant seedlings.  The primary objective of these treatments is to mimic some natural disturbance process, mainly wildland fire, to facilitate whitebark regeneration and cone production.  Two sources are available as detailed references for evaluating, designing, and implementing whitebark pine treatments.  Keane and Parsons (2008[inpress]) summarized results of a 15 year whitebark pine

restoration study by treatment across five diverse sites.  Keane and Arno (2001) present additional summarized material that can be used for the same purpose.

Mechanical cuttings include treatments that manipulate the stand by cutting trees.  To date, there have been three types of mechanical cuttings.  Keane and Parsons (2008[in press]) created a series of nutcracker openings in successionally advanced subalpine fir stands containing dying, rust infected whitebark pine.  These nutcracker openings were near-circular areas within which all trees except whitebark pine were cut.  The size of these areas can vary but they can be anywhere from 1-30 acres based on a study by (Norment 1991) who found nutcrackers appeared to favor burn patches less than 15 ha in size.  The nutcracker openings are a cutting treatment that attempts to mimic patchy, mixed severity wildfires.  Other cutting treatments include group selection cuts where all trees except whitebark pine are sawn down, and thinnings where all non-whitebark pine trees below a threshold diameter are cut (Chew 1990, Eggers 1990).  One last cutting is a fuel augmentation or fuel enhancement treatment where subalpine fir trees are directionally felled to increase fuel loadings and contagion (Keane and Arno 1996, Keane and Arno 2001).

Keane and Parsons (2008[in press]) found that lodgepole pine trees could be left on site if they occur in low densities (<50 trees acre-1).  Whitebark pine can compete with lodgepole pine on most upper subalpine sites with acceptable regeneration and grow underneath scattered lodgepole pine (Arno and Hoff 1990).  It is also important to reduce or remove the slash from the treatment area to allow nutcrackers access to the ground for caching.  This can be done by piling the slash and then burning the piles, or it can be done by whole tree skidding the tree to a landing to remove the branches, or it can be done by augmenting the cutting with a prescribed fire.  (Waring and Six 2005) found some Ips beetle activity killing live whitebark pine trees from piles that were left for one year.  Cutting treatments can be commercial timber harvests if 1) the trees are large enough, 2) the area is accessible by road, and 3) there is a market for the timber.  Often, National Forest ranger districts have implemented cutting treatments using outside funding from various foundations or institutions.

Prescribed burning

Prescribed burning may be the most desirable treatment because it best emulates wildland fire, but it is also the most difficult and risky to implement.  Prescribed burns can be implemented at three intensities to mimic the three types of fire regimes.  The

primary objective of low intensity prescribed fires is to kill the subalpine fir understory and perhaps overstory and to preserve the whitebark pine component. 

The ignition method is important in this ecosystem.  Most prescribed fires were ignited using strip head-fires where the width is increased if higher fire intensities were desired.  However, some study sites are so moist when they need to be burned with very wide strips.  Keane and Arno (2000) used both the terratorch and heli-torch in their study and burned large areas with the target high intensities.  However, these techniques may not always be available.  That leaves drip torches as the primary ignition technique and, to be effective, these ignitions should be done in dry conditions if high intensity fires are the objective of the burn.  Another way to achieve high severity prescribed fires is multiple burns if possible.

We recommend a fuel enhancement cutting be implemented one year prior to a prescribed burn to ensure burn objectives are fully realized.  The addition of cured slash to discontinuous fuelbeds facilitates burn effectiveness by providing additional fine fuel to 1) aid fire spread into all areas of the stand and 2) augment quickly drying fine fuel levels so the burn can be implemented in moister conditions.  Prescribed burns have a greater coverage and higher severity in stands where the fuels were enhanced.  Fuel enhancement is an easy, cheap, and fast treatment that can be done by timber crews, fire crews or contractors.  Keane and Parsons (2008[in press]) also found that shrub and herbaceous fuels were much drier after the first hard frost in late summer or early autumn.  This frost kills the aboveground foliage that allows the plants to take water from the soil so the entire plant structure can dry sufficiently for burning.