Adaptive Management Projects
Project Summary: Influence of Lodgepole Pine Stand Density on Red Squirrel Populations, Feeding Damage, and Wildlife Habitat Diversity Operational Demonstration Areas
FRDA II (Canada - BC Partnership)
Contacts:
Ralph Winter - Silvicultural Practices Branch
Thomas P. Sullivan
Background:
To date, experiments with tree squirrels and habitat alteration via stand thinning have been short-term (1 year) and at a research scale (1-2 hectares). What would be the response of red squirrel populations and their feeding damage to a range of stand density manipulations of lodgepole pine conducted at a large-scale (operational) level? A secondary question is, could this approach combine stand protection with an optimum thinning regime for growth rates of lodgepole pine crop trees? A third question is, what effect does this habitat alteration have on understorey vegetation in terms of wildlife habitat diversity?
Objectives:
This study was designed to determine the effect of large-scale habitat alteration by stand thinning (operational demonstration areas) on red squirrel populations and feeding damage in young lodgepole pine stands. Additional objectives included integration of stand productivity with protection and wildlife habitat diversity as represented by plant and small mammal communities.
- Determine the effect of large-scale habitat alteration by stand thinning on red squirrel populations and feeding damage in young lodgepole pine stands.
- Determine the growth responses of lodgepole pine crop trees at different stand densities.
- Determine the responses of vegetation (herb, shrub, and tree layers) and small mammal communities as a measure of wildlife habitat diversity.
Experimental Design:
Each study area had three stands thinned to densities of approximately 500 (low), 1,000 (medium), and 2,000 (high) stems/hectare with an unthinned juvenile pine stand and old growth pine stand for comparison. Squirrel populations were sampled intensively in the thinned stands from 1989 to 1991; feeding damage was assessed annually from 1989 to 1993. Five-year diameter and height increments were measured in the thinned stands at Penticton and Prince George, and 4-year increments in these stands at Kamloops. Small mammal populations were intensively sampled by live-trapping in the five stands at each study area in 1990 and 1991. Vegetation (herb, shrub, and tree layers) was sampled in the five stands in 1990 and 1993, yielding biomass (volume in m3/0.01 hectare) measurements for all plant species.
The three study areas acted as regional replicates in an experimental design with true replication of experimental units. In addition, the experimental units were all operational size in terms of scale, and hence the study design essentially followed adaptive management (Sullivan, 1993 - page 56). This approach is superior to that used in small- scale experiments where small-area (1-10 hectare) patches of habitat are treated, which yield results of limited applicability to management.
Monitoring:
Note that no measurements were taken prior to treatments for comparison of before and after.
Study areas were located at Penticton Creek in the Penticton Forest District, Lac Le Jeune in the Kamloops District, and at a site 60 km west of Prince George in the Vanderhoof District. Each study area contained three experimental stands (A, B and C) averaging approximately 25 hectares in size.
Results:
Manipulation of stand thinning in young lodgepole pine has indicated that both stand protection (from squirrel feeding damage) and productivity are enhanced by reducing the number of stems/hectare. Based on the 5-year post treatment period, it is clear that in thinned stands, the increasing biomass of herbs and shrubs and diverse assemblage of plant species is developing complex stand structure, and hence wildlife habitat diversity.
Time Frame:
1989-1993
Costs:
$350,000 over the five year period.
Current Status:
Red squirrel populations were significantly reduced in the low density stand compared with either the medium or high density stands at Penticton and Prince George. Squirrels were less abundant in both the low and medium density stands in Kamloops. There is a ten year re-measurement of crop trees, understory vegetation, and small mammal communities planned for 1998.
References:
Sullivan, T.P. (FRDA II). 1993 Influence of Lodgepole Pine Stand Density on Red Squirrel Populations, Feeding Damage, and Wildlife Habitat Diversity: Operational Demonstration Areas. FRDAII.
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