1) Access mats reduced the negative impacts of industrial traffic on soil physical characteristics like penetration resistance and water infiltration rates in a Mixed Grass Prairie ecosystem, compared to areas with direct unmitigated traffic. 2) Soil penetration resistance and moisture content returned to natural levels faster under access mats after they were removed, whereas areas with direct traffic remained more compacted. 3) Higher water infiltration rates were observed in loamy soils than sandy soils, likely due to higher clay percentage increasing compaction in sandy soils from heavy traffic loads.

1. WI rates were not significantly
different between access mat
and control plots, but were
significantly higher in traffic
only plots (Fig. 13).
Figure 14.
Infiltration
ring (left).
Higher WI rates were
observed in loamy soils than
in sandy soils, likely due to
higher clay percentage
resulting in reduced porosity
and high soil compaction from
heavy traffic.
Soil Moisture Content (SMC)
Figure 5. July 22, 2016
Initial mat removal
Access Mats Reduce Mixed Grass Prairie Soil
Physical Responses to Industrial Traffic
Kassia James1, Edward Bork1*, Cameron Carlyle1, Faezeh Najafi1 and Sylvie Quideau2
1Department of Agricultural, Food And Nutritional Sciences; 2Department of Renewable Resources; *Correspondence: edward.bork@ualberta.ca
Acknowledgements
We thank Caroline Martin, Eric Schell and Christian Kentz for field assistance.
This work was supported by funding from:
Conclusions and Implications
References
1Alberta Sustainable Resource Development, 2010. Industrial activity in foothills fescue grasslands:
Guidelines for minimizing surface disturbance. Edmonton, AB, Canada: Report, ASRD Lands Division.
2Dollhopf, D.J., M.D. Mitchem, C.S. McWilliams, and S.J. Gundlach., 2007. Effect of oak matted drill
pads on plant and soil resources. Pinedale, WY, USA: Report KC Harvey, Soil and Water Resources
Consulting, for US Bureau of Land Management.
3Mitchem, M.D., D.J. Dollhopf, and K.C. Harvey. 2009. Reduced-impact land disturbance techniques for
natural gas production. In: Proc. National Meeting of the American Society of Mining and Reclamation,
Revitalizing the Environment: Proven Solutions and Innovative Approaches (May 30- June 5, 2009),
Billings, MT, USA.
Penetration Resistance (PR)
Figure 7. October 15, 2015
12 week after mat removal
Figure 6. September 3, 2015
Six weeks after mat removal
Figure 8. June 17, 2016
47 weeks after mat removal
Best management practices should minimize direct traffic on soils within
Alberta’s Mixed Grass Prairie ecosystem. Results indicate that access mats
may alleviate the impacts of industrial traffic on soil physical characteristics.
Results and Discussion
Figure 2. Access mat, weighing 0.75 tonne,
three-ply alternating spruce boards
Water Infiltration (WI)
Context
Figure 3. Traffic treatment
imposed by loader
Figure 4. Un-matted plot
after treatment by loader
Figure 10. June 17, 2016
47 weeks after traffic on
an un-matted plot
Figure 9. June 17, 2016
native MGP control plot
sandy soil site
Figure 11. Mean PR (+/- SE) at three times, p<0.05.
Figure 13. Mean (+/- SE) WI rates on two soil
types, from July 22, 2015, p<0.05.
Traffic only plots had 1.8x longer or 1.5x longer
WI rates in loamy and sandy soils compared to
control plots.
Access mats were originally used
for drill rig access in boreal forest
sites but are recommended
routinely as a conservation ‘best
management practice1’ for other
settings, despite limited data
testing their effects.2,3
Access mats create temporary
roadway access and construction
platforms on sensitive or unstable
ground. Use of access mats is
becoming more common place.
Transmission line construction has
adapted use of access mats on
Alberta’s rangelands. Weight
redistribution of heavy equipment
is thought to reduce negative
impacts on soil physical properties.
On April 30, 2015 access mats were placed for 12 weeks on two sandy and
two loamy Mixed Grass Prairie (MGP) sites. At each site, plots were
established in a RCBD design with four replicates, which included matted,
un-matted, and control plots. A 28-ton loader drove four times over the
access mats and un-matted plots after placement and prior to removal.
Penetration resistance (PR) and soil moisture content (SMC) were
measured after access mat removal, six, and 12 weeks later in the 0-15 cm
soil depth. Water infiltration (WI) rate, defined as the time required for 2.5cm
to infiltrate the soil, was sampled in late July in all treatment plots.
After access mat
removal, PR was
significantly different
between treatments;
over time PR in
access mat plots
returned to natural
levels.While un-
matted plots PR
remained significantly
greater throughout
(Fig. 11.).
Direct un-matted traffic increased soil compaction and PR; it is unknown
whether soil compaction and PR will return to natural levels with future
freeze-thaw cycles. Access mats mitigated the effects of traffic on PR and
soil compaction.
Study Area and Methods
Direct traffic on soil is
thought to create soil
compaction, increase
bulk density, alter
hydrologic function, and
negatively impact plant
growth.
Figure 1. Access mats in place during
transmission line construction.
Figure 12. Mean SMC (+/- SE) averaged by soil
type, p<0.05.
SMC under mats was initially
2.5x greater than in control
plots. After access mat
removal, SMC levels declined
to natural levels.
High initial SMC under mats
was likely a combination of
reduced moisture utilization
by plants and limited
evaporative losses.
SMC data on access mat and
control plots only, due to
compaction on traffic only plots
and probe inability to penetrate