EP1179

Project Summary

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Project:

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

Project Number:

EP1179

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:

Information is required by forest land managers to evaluate the impacts of vegetation management treatments on biodiversity, vegetation community development, crop tree development, and wildlife forage. Information documenting the long term consequences of vegetation management treatments is scarce to nonexistent both in B.C. and elsewhere in the world. However, concern has been raised over the potential effects of large scale herbicide applications on biodiversity, wildlife forage and forest health.

The Bush River Trial established in 1986 by Roger Whitehead of the Canadian Forest Service offers an opportunity to study the long term impact of herbicide and manual vegetation management treatments on conifer survival and growth, vegetation community development and wildlife forage values.

Objectives:

To document and compare vegetation diversity , vegetation community development, conifer development and wildlife forage values within the Bush River herbicide/manual brushing trial 8 years after treatment.

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:

The brushing trial consisted of a randomized complete block design with 3 replicates of 4 treatments for a total of 12 treatment plots located over 3 blocks.
Each treatment plot measured 60 X 60 m (Figure 1)
Within each of these plots, 20-10 m² circular subplots were established for measuring target vegetation
A 400 m² plot was established within the large plot to assess plant community dynamics and species diversity
30 Se seedlings were selected at random within each treatment plot for assesment of crop growth response of each seedlot
Stem mapping was used on 2 - 50m² circular subplots within each plot to track seedling survival

Sites:

Bush River Brushing Trial Site

Major Findings:

The total number of plant species present varied considerably over all plots, independent of treatment. Total number of species are higher in glyphosate than in other treatments due to the ability of invading plant species to colonize on exposed sites. The initial reduction of shrub and herb cover of naturally occurring species following herbicide application probably allows for the establishment of such "invaders".

The plant species treated with glyphosate exhibited generally poor vigour, even 8 years after treatment. Excellent vigour ratings were more frequent in the manual and control treatments than in the glyphosate sites.

Shrub and herb heights in the glyphosate treatment were consistently lower than in all other treatments (Figure 2). Also, conifers on the glyphosate plots were 35% taller than on all other treatments (Figure 3). Apparently, glyphosate is a useful tool for controlling brush competition, and for releasing regenerating conifers.

This study confirms previous research that documented increased height, vigour and crown diameter of conifers with the application of glyphosate. The percent cover for conifers in the glyphosate treated area is more than 100% greater than that of the control and manual treatments. This equates to increased photosynthesization, increased volume, and increased fibre production.

Related Projects:

EP1195 Bush River Brushing Trial

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

Clement, C., and B. Keeping. 1996. Evaluation of Forest Vegetation Community Dynamics on the Bush River Brushing Trial Site. For. Can. and B.C. Min. For., Victoria, B.C. FRDA Report No. 241.

Harper, G. and R. Whitehead. 1994. Evaluation of forest vegetation community dynamics, biodiversity and wildlife forage values 8 years after herbicide and manual brushing treatments on the Bush River Trial site. Working Plan. E.P. 1179. B.C. Min. For., Research Branch, Victoria.

To obtain any publications that are not highlighted click here.

Acknowledgments:

Support for this project has been provided by the B.C. Ministry of Forests, the Canada-British Columbia Partnership Agreement on Forest Resource Development (FRDAII), and Forest Renewal BC.