Methods

Site Characteristics

This study was conducted in a burned subalpine forest near Bearberry, Alberta, within the Clearwater County’s area, which burned in wildfire RWF070 (July 2021). The site consists of mature burnt Pinus contorta (Lodgepole pine) and Picea glauca (white spruce), with varied snag densities, making it ideal for studying post-fire regeneration and microclimate effects. Specifically, we will be examining lone standing snags with no nearby structures, dense snag areas with approximately 1,100 snags per hectare, and open areas with no snag influence.

Image 3. Individual open area snag example.

Image 4. Dense stand snag treatment type.

Experimental Design

Eighteen 100 m² basal area plots were established: 12 in dense snag stands and six around individual open area snags. Each plot included Lodgepole pine snags with and without stemflow devices, paired with soil moisture sensors and Populus tremuloides (Aspen) seedlings. Open control plots provided baseline comparisons. Rainfall and throughfall were measured using rain gauges.

Image 5. Basal area plot design.

Stemflow Measurement

Stemflow was collected using a spiral-wrapped hose system secured to snags with wood screws and sealed with waterproof silicone. A shallow groove was cut into the bark for a flush fit. Water was funneled into tipping buckets connected to HOBO Pendant Event Loggers, which recorded tipping events (Williams et.al., 2019). Stemflow volume was converted to L/m^2 based on snag diameter and height (Treated as a cone).

Image 6 and 7. Image of the stemflow device setup in the dense stand and a closer image of how the hose was attached to the snag using silicone and screws.

Seedling Bioindicators

A total of 200 Aspen seedlings were planted on May 20, 2024, in four locations: (1) between snags, (2) under snags with stemflow devices, (3) under snags without stemflow devices, and (4) in open areas. While aspen is not a primary species for commercial forestry, its high sensitivity to environmental changes makes it a valuable bioindicator (Kreider & Yocom, 2021). Seedling height, leaf area, and leaf water content were recorded at planting and the end of the growing season. There were 3 seedlings planted around each snag, 3 in each center of the plot, and 15 in the open area.

Soil Moisture Monitoring

Soil moisture relative to Populus tremuloides seedling was measured using TOMST TMS-4 Microclimate Extremes in every treatment type. There was 1 planted in the enter of the basal area plots, and 1 planted next to every Aspen seedling that was planted in the snag root flare zone (image 5).

Image 8. Picture of the dormant, 1 year old- nursery grown Aspen seedlings that were planted as bioindicators throughout the study.

Image 9. Picture of Aspen seedling planted in the root flare next to the TOMST TMS4 Microclimate Extreme soil moisture sensor.

Page updated

Report abuse