1. Forest vegetation responses to atmospheric depositions associated with oil sands mining operations
Macdonald, S. Ellen1, Mark Fenn2, Mervyn Davies3 and Benoit Gendreau-Berthiaume1
1Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
2United States Department of Agriculture, Forest Service, PSW Research Station, Riverside, California, USA
3Stantec Consulting Ltd., Calgary, AB, Canada

2. Vegetation assessment
Jack pine dominated sites; Dry, poor soils, flat
Thought to be sensitive to acid deposition
Understory plant community
Species richness – total and by vegetation type (mosses, lichens, forbs, graminoids, shrubs)
Cover – total and by vegetation type
Species composition (cover by species)
Branch growth (canopy trees)
Basal Area Increment of canopy trees (dendrochronological analysis of tree cores)
pre-oil sands development ( )
Recent ( )

3. Understory vegetation cover and richness (regressions):
Positively related to several measures of N, S, Base cations, Potential Acid Input
Negatively related to distance from center of oil sands mining
Understory vegetation composition related to (constrained ordination):
Potential Acid Input
Base Cations
Sulphur
Nitrogen
Macdonald, S. Ellen Chapter 9. Responses of understory vegetation. pp In. Assessing forest health in the Alberta Oil Sands Region. T.A. Clair & K.E. Percy (editors). Wood Buffalo Environmental Association Report # pp.

4. P = 0.0395; R2 = 0.2264 P = 0.014; R2 = 0.304 Vascular Plant cover (%)
Total Richness
P = ; R2 =
P = 0.014; R2 = 0.304

5. Forward selection of environmental variables in distance-based redundancy analysis

6. Center of oil sands mining
Higher richness and cover
Lower richness and cover

7. Branch growth (mean length of most recent branch internode for 10 trees per site) was inversely related to Potential Acid Input; not related to distance from centre of oil sands mining
P = 0.024, R2 = 0.242
Macdonald, S. Ellen Chapter 6. Plot vegetation description. pp In. Assessing forest health in the Alberta Oil Sands Region. T.A. Clair & K.E. Percy (editors). Wood Buffalo Environmental Association Report # pp.

8. Tree growth: possible to compare among sites for the time period before oil sands development and recent

9. BAI Pre-development (1957 – 1966): not related to (current) base cations, potential acid input or any other deposition variables
Canopy trees: 54 – 68 years old at breast height in 2011

10. Not related to distance from centre of oil sands mining
Recent ( ) BAI positively related to base cations and negatively related to potential acid input
Not related to distance from centre of oil sands mining
Mixed effects model: P =
Mixed effects model: P =

11. Base cation inputs Center of oil sands mining
JP 317
Trees growing faster; higher base cations
Base cation inputs

12. Fertilization effect on understory vegetation?
Understory plant cover and richness were greater in areas with higher N, S, base cation deposition and with higher Potential Acid Input
Areas with richer/more abundant understory vegetation are generally closer to the oil sands development
Understory composition also varied with N, S, base cation deposition
Sites closer to oil sands mining had increased cover and richness of forbs and trailing shrubs
Fertilization effect on understory vegetation?
Recent tree growth is lower in areas with lower base cation inputs and higher Potential Acid Input
This effect did not exist prior to oil sands development
The areas with slower-growing trees are not necessarily closer to the oil sands development
Tree growth was not related to N or S deposition variables

13. Moving forward:
Analyze data from the edge sites
Variation in space could be confounded with: topography, soils, parent material, microclimate, atmospheric CO2…..
How have depositions changed over time – past and into the future? (changing technologies, new developments coming on-line)

14. Acknowledgements
Wood Buffalo Environmental Association
Kevin Percy, Tom Clair
Navus Environmental (Kevin Renkema, Ashley Craig)