Talia collecting soil respiration data

Northern highbush blueberry did not promote peat respiration in Burns Bog.

Sustainable Agriculture Student Research Project

Soil respiration beneath northern highbush blueberry and indigenous plants at Burns Bog

Talia Parfeniuk, Rue Badanic, and Michael Bomford, Kwantlen Polytechnic University Department of Sustainable Agriculture and Food Systems

Introduction

  • Peat soils are the largest terrestrial carbon sink.
    • The planet's peatlands store a third of terrestrial carbon on ~4% of its terrestrial surface area.
    • Canada's peatlands store 56% of its terrestrial carbon on ~12% of its terrestrial surface area.
    • Peat formation sequesters carbon belowground, countering climate change.
    • Peat decomposition releases long-sequestered carbon into the atmosphere as carbon dioxide, contributing to climate change.
  • Soil respiration is the carbon dioxide released by plant roots and microbial decomposition of peat.
  • Northern highbush blueberry (Vaccinium corymbosum L.) is invasive in local peatlands:
    • Native to Eastern North America
    • Escapes from local blueberry farms, where it is widely cultivated
    • Forms dense thickets up to 3.8 m high, crowding out locally indigenous berries (Fig. 1)
      • e.g. Indigenous bog bilberry (Vaccinium uliginosum) and velvetleaf blueberry (Vaccinium myrtilloides) grow to 30 and 50 cm, respectively
    • Rare in undisturbed peatlands, but abundant in disturbed peatlands
    • May support microbial communities that promote peat decomposition 
Bog bilberry and northern highbush blueberry
Figure 1. Bog bilberry and northern highbush blueberry at the Garden City Lands, 23 months after mowing. The latter has a much taller growth habit and quickly forms dense canopies (photo: M. Bomford).

Objective

Compare soil respiration from peat below northern highbush blueberry and native vegetation in disturbed and intact areas of Burns Bog.

Methods

  • The study was conducted in July - October, 2025 in a section of Burns Bog that was previously mined for peat (disturbed) and another section that has never been mined (undisturbed)(Fig. 3)
    • 5 m x 5 m replicate blocks were identified at the disturbed site (n = 12) and the undisturbed site (n = 10). Each block was partially dominated by northern highbush blueberry (invaded) and partially dominated by native vegetation (uninvaded).
Burns Bog study sites
Figure 3. Location of disturbed and undisturbed study sites (blue rectangles) near the western edge of the Burns Bog protected area. Burns Bog is one of several large bogs that formed over alluvial soils near the mouth of the Fraser River.
  • Soil respiration was measured in µmol of CO2 emitted per square meter per second using a 10 cm diameter soil respiration chamber (SRC-2, PP Systems, Amesbury MA) attached to a portable infrared gas analyzer (CIRAS-3, PP Systems, Amesbury MA). Gas was allowed to accumulate in the chamber for 150 seconds per sample. Respiration rate was estimated by fitting a quadratic equation to the CO2 accumulation data.
  • Samples were collected on July 4th, September 6th, and October 10th.
  • Soil volumetric water content in the top 20 cm was measured on October 10th by taking five readings at each sample location with a soil moisture meter (Fieldscout TDR 350, Spectrum Technologies, Auroera IL).
  • Data were analyzed by linear mixed model analysis using the GAMLj3 module (version 3.6.2) for the jamovi interface to R (version 4.5). Date, location (disturbed or undisturbed), and condition (invaded or uninvaded) were considered fixed factors, with block as a random factor.

Results

  • Soil respiration averaged 4.1 ± 0.3 µmol CO2 m-2 s-1. An interaction was detected between sample month and location (p = 0.003): Respiration was higher in the undisturbed than the disturbed areas in September only (Fig. 4). Due to this interaction, respiration was higher in the undisturbed areas than the disturbed areas, and higher in September than October.
  • Month * location interaction
    Figure 4. Soil respiration in undisturbed (blue) and disturbed (yellow) areas of Burns Bog by sample date and location. Error bars denote 95% confidence interval. Means labelled with the same letter do not differ significantly (Tukey test, Undisturbed n = 10; Disturbed n=12, α = 0.05)
  •  No significant differences were detected between invaded and uninvaded areas (Fig. 5).
Respiration by condition and location
Figure 5. Soil respiration at Burns Bog by sample location and condition. Invaded and uninvaded samples were taken below northern highbush blueberry plants and native vegetation, respectively. The disturbed section was previously mined for peat but the undisturbed section was not. Error bars denote standard error around each mean. Means do not differ significantly (Undisturbed n = 10; Disturbed n = 12).
  • Volumetric water content in the top 20 cm of soil was 45.5 ± 0.9 % on October 10th. No differences were detected between the disturbed and undisturbed locations or between the invaded and uninvaded conditions (Fig. 6).
Volumetric water content
Figure 6. Soil volumetric water content in the top 20 cm at Burns Bog on October 10, 2025. Invaded and uninvaded samples were taken below northern highbush blueberry plants and native vegetation, respectively. The disturbed section was previously mined for peat but the undisturbed section was not. Box bottoms, mid-lines, and tops show the 25th, 50th, and 75th percentiles, respectively; whiskers show the range (n = 8). No significant differences were detected between means.

Conclusion

  • We found no evidence that northern highbush blueberry is drying Burns Bog or promoting soil respiration.

Acknowledgements

  • Talia Parfeniuk and Rue Badanic received a KPU Student Research and Innovation Grant for their research contributions to this project.
  • Metro Vancouver granted access to the restricted area of Burns Bog and Cranwest Farms granted bog access through its property to conduct this work.

Raw data