EP1195: Bush River Brushing Trial

Project Summary

Return to: EP1195

Project:

Bush River Brushing Trial

Project Number:

EP1195

District(s):

Golden

Location:

Bush River

Project Leader(s):

George Harper, B.C. Ministry of Forests, Research Branch, Victoria

Contact:

E-mail:	George.Harper@gems4.gov.bc.ca
Phone:	(250) 387-8904

Trial Established by:

Roger J. Whitehead, Canadian Forest Service

Introduction:

The most productive biogeoclimatic zone for timber growth in the interior of British Columbia is the Interior Cedar Hemlock (ICH) zone. Mixed and herb complexes often occupy moist and rich sites very rapidly following harvest and site preparation in this zone and early survival and growth of conifer plantations can be severely reduced by physical damage or by competition for light and limited growing space. Species of major concern in the ICH include those which rapidly exploit openings through vegetative means after disturbance, such as thimbleberry (Rubus parviflorus Nutt.), red raspberry (Rubus idaeus L.) and fireweed (Epilobium angustifolium L.).

Information on the effectiveness of vegetation control treatments in specific brush complexes, and the longer-term response of conifer seedlings and plantations is needed.

Objectives:

To compare the effect of four vegetation control treatments on percent cover and height of a Rubus-Epilobium brush complex.
To compare the effect of four vegetation control treatments on survival and growth performance of planted Engelmann spruce seedlings.

Treatments:

Treatment	Application Rate	Equipment
1) glyphosate herbicide (Roundup®)¹	broadcast @ 1.8 kg ai/ha²	CP-3 backpack sprayer
2) 2,4-D amine herbicide (Forestamine®)	broadcast @ 3.0 kg ai/ha²	CP-3 backpack sprayer
3) manual brushing	not applicable	Husqvarna® 165r clearing saws (MAXI 255 circular blades)
4) control (no treatment)	not applicable
¹ Currently registered as VISION for forestry use. (ROUNDUP was used for this trial in 1986.) All treatments were applied over a 9 day period in mid to late August of 1986. ² Applied in water carrier at 40 litres total solution/ha.

Layout:

Twelve 60 m X 60 m treatment plots were established in a randomized complete block design for three replicates of four treatments.
Percent cover and height of thimbleberry, raspberry and fireweed was assessed before and up to five years after treatment.
Conifer height, diameter and condition were measured before and up to ten years after treatment.

Sites:

Bush River Brushing Trial Site

Figure 1. Aerial View of Bush River Brushing Site (125k gif).
Figure 2. Ground View of Bush River Brushing Site (105k gif).

Major Findings:

Of the three treatments compared to an untreated control, broadcast application of glyphosate in late August at 1.8 kg a.i./ha was most effective in reducing cover and height of the major target complex. Manual cutting and broadcast application of 2,4-D Amine at 3.0 kg a.e./ha had minor and short-lived effects.

Engelmann spruce seedlings responded positively to reduction of cover and height of the target vegetation complex. Indicators of competitive stress, including seedling height:diameter ratio and competition index, were reduced following glyphosate treatment and remained at lower levels relative to all other treatments tested throughout the measurement period.

Conifer height and diameter growth curves for the four treatments diverged over time, with seedlings in the glyphosate treatment growing at a faster rate than seedlings in all other treatments.

Application of glyphosate to control weeds appears to have enhanced the growth on the crop trees in this experiment. In general, the effects on height were more pronounced for the second planting than the first, whereas the effects on diameter and height/diameter were more obvious in the first planting compared with the second.

Related Projects:

EP1179 Evaluation of forest vegetation community dynamics, biodiversity and wildlife forage values 8 years after herbicide and manual brushing treatments on the Bush River Brushing Trial site.

References and Publications (Click on Highlighted References to Obtain an Electronic Copy in PDF Form):

Linnell Nemec, A.F., 1997. Comparison of four treatments for weeding spruce plantations: analysis of 1996 Bush River data. Internal Report. B.C. Min. For., Research Branch, Victoria

Whitehead, R.J., and G.J. Harper. 1998. A comparison of four treatments for weeding Engelmann spruce plantations in the Interior Cedar Hemlock Zone of British Columbia: ten years after treatment. Draft. Can. For. Ser., Pacific Forestry Centre, Victoria, B.C.

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