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 Premier Ridge Ecosystem Restoration 1998/99

Executive Summary

Approximately 610 hectares of open range, open forest and closed forest habitat types were burned in April of 1998. The burn was divided into two operational areas due to the variability of the green-up along the elevation rise on Premier Ridge. The Ministry of Forests and BC Environment organized and implemented the burn, with the assistance of volunteers from various wildlife groups in the area. Overall, the burn was considered a success with numerous small Douglas-fir regeneration being killed, rejuvenation of old mature plants of bitterbrush with young palatable shoots, and a dramatic flush of Saskatoon following the burn. In order to maintain the openness of Premier Ridge, burning will be required on a more regular basis to keep the Douglas-fir in check.

Background

Premier Ridge is widely acknowledged as a critical winter range for elk, mule deer and Rocky Mountain bighorn sheep and to a lesser extent whitetail deer. However, due to fire suppression over the last 60 years, forest encroachment has seriously reduced the available landbase for wintering wildlife and areas once considered open range are now dense thickets of forest.

The Ministry of Forests, in co-operation with the Ministry of Environment, Land and Parks and other stakeholders have developed an Ecosystem Restoration Plan for the Rocky Mountain Trench. The driving principle behind the restoration plan is to return the Trench to a healthier ecosystem in which low intensity fires burned every 7 to 15 years. This will provide better foraging opportunities for wildlife by restoring the critical winter range to historical production levels and by providing opportunities for more desirable species, such as rough fescue, bluebunch wheatgrass and Saskatoon, to increase in abundance. As well, the increase in plant diversity will translate into greater wildlife diversity in that ground nesting birds and small mammals which prefer open range and open forest characteristics will also benefit from the restoration plan. All range units in the Trench have operational treatments identified (harvesting, slashing, spacing, burning) that will be required to meet the goals of the restoration plan. The Premier Ridge Ecosystem Restoration project, which falls under the greater encompassing Trench Ecosystem Restoration Plan, all originated out of the strategic plan detailed in Section 3.10 of the Kootenay-Boundary Land Use Plan Implementation Strategy as "Management Guideline for Fire-Maintained Ecosystem Restoration".

 Objective

The objective of this project was to:

  • maintain existing open range and open forest stands by reducing the number of Douglas-fir stems under 2 meters
  • reduce the number of tree stems (< 3 meters ) on closed forest stands
  • rejuvenate the decadent stand of bitterbrush
  • reduce the density of bitterbrush (Purshia tridentata) and
  • improve the abundance of desirable vegetation (rough fescue, bluebunch wheatgrass, Saskatoon).

Technical Details

The project was carried out on two separate days. On April 9 the lower half of Premier Ridge was ignited and on April 20 the upper half. With the elevation difference on the ridge, green-up was occurring faster on the lower half than the top half. An old road that bisected the burn was used to separate the area into two burns.

The use of existing roads and trials were used whenever possible for fireguards. A small caterpillar was used to refresh some of the old trails to minimize any escapes outside the burn boundary. Of the approximate 13.6 km of fireguard required, only 700 meters of new fireguard had to be established. The remainder was on old trails that were just refreshed.

Ignition of the burn was carried out by ground crews along the perimeter, starting at the northern end of the burn. As the ground crews progressed southward, lit-up of the interior of the burn was done by helicopter using Aerial Ignition Device (AID) balls. These balls were laid in strips and the distance between strips was dependent on slopes and fuel loading. As forecasted, south winds picked up in the afternoon, fanning the fire, consequently, the strips were placed farther apart at the southern end of the burn allowing the fire to become more intense with greater flame height. It was hoped with this greater intensity, higher mortality of the smaller Douglas-fir would result.

A day after each burn, a mop-up crew patrolled the perimeter of the burn to extinguish any hot spots to minimize the possibility of any escapes.

Results

The prescribed burn treatment encompassed 610 hectares, all of which was burned. Due to wind speed, changes in relative humidity, and fine fuel loading, fire intensity was variable. Consequently, results are variable throughout the burn. A combination of results were tracked before and after the burn - vegetation composition, forage production and photo points.

VEGETATION COMPOSITION:

The exclosure and other permanent transects in the burn will track long-term changes in the plant community. The permanent exclosure was established in 1990 on the lower slope of Premier Ridge. Vegetation cover has been collected on this exclosure in 1991, 1993, 1994 and in 1998. Data was collected both inside the exclosure (no livestock or wildlife grazing) and outside (wildlife grazing any time of the year and livestock use on a rotational basis).

The summer following the burn, the cover of bitterbrush, outside the exclosure drastically decreased, whereas the cover of Saskatoon, outside increased in cover (Fig. 1). The other species of shrubs found on site showed that rose, spirea and snowberry, as well as Saskatoon, all responded positively to the burn (they increased in percent cover), both inside and outside the exclosure (Fig. 2 and 3). Bitterbrush and soopolallie responded negatively to the burn in that their percent cover decreased.

FIGURE 1.

FIGURE 2.

FIGURE 3.

In regards to the grass composition on the burn, the lower portion of the ridge is hotter and drier, so the desired bunchgrasses would be bluebunch wheatgrass, Needle and Thread and to a lesser extent rough fescue. On the higher elevations on the ridge, more rough fescue and less pinegrass would be desired. In looking at the exclosure, changes in grass cover has occurred after the burn. Kentucky bluegrass cover dropped significantly after the burn, both inside and outside the exclosure (Fig. 4 and 5). This would indicate the burn has an influence on Kentucky bluegrass cover. It has been reported that late spring fires where Kentucky bluegrass plants have been growing for a month or more have an effect in reducing their cover. This was not the case on this burn as green-up around the exclosure was just starting for a few of the plants. Monitoring the cover of Kentucky bluegrass in years to come will hopefully provide some more insight on this.

FIGURE 4.

FIGURE 5.

FORAGE PRODUCTION SUMMARY:

Four cages were clipped in 1997 prior to the burn and clipped again in 1998 after the burn. Table 1 outlines the production found on each of these sites and the corresponding average.

 

Table 1.       Pre and Post Burn Forage Production (Kg/Ha).

Site

Grass

 

Forbs

 

Shrubs

1997

1998

 

1997

1998

 

1997

1998

1

543

469

 

65

26

 

12

274

2

866

500

 

86

282

 

86

88

3

520

394

 

725

61

 

911

2176

4

1687

852

 

29

61

 

689

54

   

AVERAGE

904

554

 

226

108

 

424

648

One of the objectives of the burn was to rejuvenate the shrub component. One growing season after the burn, shrub production on Premier Ridge increased by 53% in comparison to the shrub production in 1997. Most of this production was from Saskatoon, based on field observations. A note of interest is that on Site #3, the 2,176 kg/ha of shrub production was almost exclusively Saskatoon. Clipping was conducted not by species of shrub, but rather all shrubs species were clumped together. Figure 6 depicts graphically the change in forage production before and after the burn for grasses, forbs and shrubs.

FIGURE 6.

Grass production decreased substantially following the burn. This is usually the case following the first year after a burn. One of the more important factors in the grass component on Premier Ridge is the grass composition on the site not necessarily the production.

PHOTOGRAPHIC RECORD

Five photo points were established prior to the burn and pictures were taken a week before, a week after and 12 weeks after the burn. As well, forage production clips were collected in 1997 and 1998 to assess any changes. Refer to the map for exact locations of photo points and clip plots. The photographic record is as follows:
Photo Point #1 - Pre-burn (April 1, 1998) Photo Point #1 - Post-burn (July 8, 1998)
Photo Point #3 - Pre-burn (April 1, 1998) Photo Point #3 - Post-burn (April 1, 1998)  Upper plateaus on Premier Ridge that faces south-west. Substantial mortality on young Douglas-fir trees.
Photo Point #4 - Pre-burn (April 1, 1998) Photo Point #4 - Post burn (July 8, 1998)   Midway up the south-west slope of Premier Ridge.  Some mortality on smaller Douglas-fir trees.  Reduction of old decadent bitterbrush plants and dramatic flush of Saskatoon.
Photo Point #5 - (April 1, 1998) Photo Point #5 - Post-burn (July 8, 1998  Lower south-west slopes on Premier Ridge.  Mainly open grassland / shrubland.   Reduction and rejuvenation of decadent bitterbrush and dramatic flush of Saskatoon.
 

Public Reaction

Prior to the burn (March 98), a open house was held in Wasa, B.C.. The intend of the open house was to inform the local residents and business of the upcoming burn on Premier Ridge. From this meeting there were no objections to the project, but overwhelmingly support to conduct similar projects throughout the Trench.

On the day of the first burn, local media (Cranbrook and Invermere) were on site to witness the burn. As a result, front page articles were in both papers and no negative comments have been voiced with the Ministry of Forests or Ministry of Environment, Land and Parks offices.

All the local wildlife and naturalists groups have voiced their support and were part of the volunteer mop-up crew used after the first burn.

Recommendations and Suggestions

This project was conducted as planned and the plant composition data has not shown any potential problems that should be corrected in future burns. However, projects using prescribed burning in the spring all have the same problem - trying to acquire funding in a timely manner in order to proceed with the burn. All the prescribed burning that will occur in Rocky Mountain Trench, and other similar areas, will be done in April. However, the final approval to proceed with the project does not occur until late May, well after the window of opportunity to do the burn under the burning plan, burning permit and risk to others. Consequently, managers have to take risks on whether to proceed with the project hoping the funding will occur, or dropping the project completely. If early spring projects could be reviewed and approval determined by March 31 of each year would greatly enhance the program.

 

 
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