Study Site Descrition

My study was conducted as part of the long term Judy Creek Mixedwood (White spruce and trembling aspen). Experiment underway 30km northeast of White Court, Alberta, Western Canada, on land licensed to Blue Ridge Lumber (1981) Ltd.

The following information regarding the history and characteristics of the site was adopted from Pitt et al. (2005) under permission. The study was established in 2002, following harvesting of a 75 years old trembling aspen dominated stands with small components of Lodgepole pine (Pinus contorta Dougl.ex.Loud) and Balsam poplar scatter throughout. Average basal area of the stand was 33m2/ha, with a mean DBH (diameter at breast height) of 26.5 cm and a stand height of 23.5m. Coarse woody debris (over 10 cm in diameter) was removed from the site during May 2002, and resulting piles were burned in December 2002, just after the first snowfall. Plots were installed and tree positions pinned, consistent with study protocols, in late June 2002. The site was planted on June 27-28, 2003, with 2+0 PSB 412 white spruce container stock. At the time of planting, these trees averaged 18.6cm in height, 3.5 mm in stem diameter, 7.5cm in crown diameter, and 0.62 cm3 in stem volume (assuming conical form). No differences were detected among treatment with respect to initial tree sizes (p>0.47).

Soils across the site tend to be luvisols, with parent material consisting of ablation till. There is a rounded cobble layer at about 25-40cm, indicating post-glacial fluvial action. Soil is generally mesic and fine-texture, with texture ranging between silty loam and clay, with a bulk density for first 20cm of 1.14g/cm3 (lower in the first 10cm and higher in the next 10 cm). Some plots have a sandy loam veneer over silty clay loam.

Both aspen and Calamagrostis were present on the site following the first growing season in 2002. Aspen cover ranged from a plot-average low of 2% to a high of 15%.? Aspen densities were relatively high, with plot averages ranging from just over 44,000 to 140,000 sph. Calamagrostis cover was lower but occurred consistently across the site, ranging from a plot-average of 0.2% to just over 2%.

Treatment

The experimental design is a randomized complete design with three or more replications of each treatment. The treatments are as following:

Spot vegetation control plots

(1) 2 years radial complete control (CCR2)

(2) 4 years radial complete control (CCR4)

(3) Radial woody control (WCR)

Broadcast vegetation control plots

(1) Broadcast complete control (CCB)

(2) Broadcast woody control(WCB)

(3) Broadcast no control(NCB)

(4) Broadcast herb/low shrub control (HCB).

Due to incomplete data, the HCB treatment were not used in this project.

Experimental plot lay out