Acidification of Sensitive Soils: More about the data

The data used to derive this indicator are based upon sampling data collected from six sites in forested areas of the province: Bruderheim, Cold Lake, Devon, Fort McMurray, High Prairie, and Rocky Mountain House. These sites were established on soils that are sensitive to acid deposition (primarily coarse-textured or sandy soils), some of them in areas subjected to acid deposition (in 1981) and that could be protected from future development for the duration of the program. Two other sites (Esther – near Oyen and close to the Saskatchewan border, and Twin Butte, near Pincher Creek) were also included in the program as non-forested sites, but data from those two sites is not included in this indicator.

High Prairie was initially selected as a representative background site, monitoring the effects of acidifying emissions entering the province from British Columbia. The Esther site was intended to monitor the effects of acidifying emissions leaving the province.

The indicator is based upon mineral soil samples collected at the 0-2 cm depth, and does not include the organic duff (LFH-Litter/Fibric/Humic) layer. Soils at this depth show the greatest response to acidifying depositions. The indicator is based upon a calculation of the mean of the pH (CaCl 2 ) from the 0-2 cm samples, of which there are 12 samples per site, and six sites in total for the indicator. The sampling periods are generally four-year time spans, as the monitoring program was set up to sample two sites per year, sampling the eight sites on a rotational basis. There was a short gap in the monitoring program from 1997 to1999. However it was reinstated in 2000.

The pH trends specific to each of the six sites used for the indicator were plotted and are located on this linked page . Slightly different trends are observed at each of the sites. However, the overall downward trend is clear, most significantly at the High Prairie and Rocky Mountain House sites.