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Impacts of Industrial Disturbances on Plant Communities in the Native Mixedgrass Prairies of Alberta

Rajat Goutam P.Eng., BIT; Dr. Edward Bork PhD

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1. Project Background 2. Study & Findings

• Access Mat Study - Impacts of Access Mat Application • Tower Study - A Comparison of Two Different Powerline

Construction Methods

3. Significance of Findings 4. Next Steps5. Questions

AGENDA

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Study Background – Significance

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“Prairies are among the most altered and least protected habitat globally” (Hickmann et al. 2013)

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Study Background

• Between 2014-2015 ATCO Electric constructed the Eastern Alberta Transmission Line (EATL) across SE Alberta

• 500 kV DC line, nearly 500 km in length from Gibbons-Redwater area ending near the town of Brooks

• Section of line tranverses the University of Alberta’s Mattheis Research Ranch

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Study Background - Location and Climate

Study Site

Location:University of Alberta’s Mattheis Research Ranch DryMixedgrass PrairieSoil Type:Brown Chernozemic Climate: Continentalclimate354 mm average yearlyprecipitation

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Study Background - Impacts of Access Mat Application

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Study Background

• What sparked the need for this study?

• After mat removal unexpected impacts were noted • Vegetation

• Moisture

• Common industry practice to use the mats and endorsed by regulators• Alberta Energy Regulator and Alberta Environment and Parks

• Limited understanding and a lack of published studies documenting the efficacy of access matting

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Study Background

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• A significant footprint is created when matting for access• Substantial cost and effort associated with cleaning, hauling,

placing and maintaining mats.

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The Study – The Application of Access Mats

• 2 Studies

• “Access Mat Study” • Evaluating the specific impact of mats in

mitigating heavy equipment traffic when used in different seasons and durations in a controlled field trial

• “Tower Study”• Assessing grassland recovery at an operation

field scale following different high voltage transmission line construction methods.

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The Study – Type of Mat

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Impacts of Access Mat Application

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The main question that arises is whether (and if so, when and how) mats should be used to optimize grassland conservation during industrial activities?

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Access Mat Study – Study Sites

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Access Mat Study – Experimental Design

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Access Mat Study – Experimental Design

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• Each treatment conducted with and without matting

• Control not matted and had no traffic

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Access Mat Study – PR & IR

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• Soil Baseline – Loam sites higher in pH, salinity and soil organic matter compared to sandy loam sites

• No change to soil baseline from treatment application(s)

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Loam Sandy Loam

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Ecosite x Treatment

Penetration Resistence End of 2016

Mat +Traffic

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Access Mat Study – Soil Moisture and Bulk Density

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• Soil moisture increase noted under mat application

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Control EARLY 6 EARLY12

LATE 6 LATE 12 ALL 24 Control EARLY 6 EARLY12

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Ecosite x Treatment

Soil Moisture End of 2016

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Access Mat Study– PRS™ Probe Application

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Access Mat Study – Soil Nutrient Summary

• 2015

• N (NO3), P, S release increased under mats (10x, 3x, 1.5x) and N, P increased under direct traffic (1.7, 1.5x)

• No Significant change from control for NH4, K, Ca, Mg

• Fe, Mn, Zn increased under mats (4x, 2.75x, 1.5x) whereas only Mn increased for direct traffic (1.6x)

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Access Mat Study – Soil Nutrient Summary Cont’d

• 2016 - Added late 12 and all 24 mat & traffic

• N increase for later 12 and all 24 but early 12 same as control

• P levels insignificant

• S had a release under all 24 mat plot but early 12 back to control levels

• Note: did see an release of micronutrients under mats in 2015 and 2016

• Some values had recovered to controls levels, indicating quick uptake of these released nutrients

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Access Mat Study – Grass Biomass Results

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• Average biomass distribution: • Grasses 66% loam, 74% sandy loam• Native forbs 21% loam and 16% sandy loam • Introduced forbs 13% loam and 10% sandy

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Access Mat Study – Grass Biomass Results

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Access Mat Study – Forbs Biomass Results

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Access Mat Study – Forbs Biomass Results

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Access Mat Study – Forbs Biomass Results

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Access Mat Study – Cover Composition Results

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Access Mat Summary

• Bulk Density did not change in almost all treatments

• Infiltration Rates showed decrease in pore sizes and connectivity, sandy loam soil more sensitive

• Penetration Resistance and Soil Moisture Content under matted treatments were equivalent to control levels one year after treatments applied

• Nutrients were released in larger amounts under matted treatment than under traffic only• Nutrients are quickly consumed within a year

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Access Mat Summary

• Sandy loam sites were more sensitive to matted treatments, shown through reduced grass biomass in most treatments

• Native forbs were released in early and long mat placements• Introduced forbs increased under all treatments except for

the early and short mat placement• Reduced competition from grasses favor forbs

• Longer mat placements did show a change in cover composition

• It is important to consider not just what was lost but what remains, the seedbank and budbank are still intact, soil aggregate structure has been mostly maintained, soil pores are reduced but still function at similar levels to controls

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Tower Study - Comparison of Powerline Construction Methods

• Assessing grassland recovery at an operation field scale following different high voltage transmission line construction methods.

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Tower Study – Low Disturbance Methods

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Tower Study – High Disturbance Methods

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Tower Study – Experimental Design

• 2015 –

• Cage placement

• Soil Sampling (texture, bulk density, pH, salinity, macronutrients)

• Soil moisture

• Vegetation sampling (biomass, cover)

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Tower Study – Vegetation Results 2015

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Tower Study – Experimental Design

• 2016 Sampling (part 1)

• PRS™ probes incorporated

• Seedling count

• First cover assessment

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• 2016 Sampling (part 2)• Soil Sampling• Soil moisture

and compaction • Vegetation

sampling • Lichen cover • Second cover

assessment

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Tower Study Results – Biomass

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Disturbed Control Disturbed Control

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Treatments and Intensity type

Grass Native Forb Introduce Forb

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Tower Study Results – Soil Properties

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• High disturbance towers display greater increase in bulk density and decrease in organic matter

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Significance of Study Findings

• What are the implications of the findings?

• What are the combined conclusions ?

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Implications (Access Mat Study)

• Sandy Soils are more sensitive to access mat impacts

• Longer duration of access mat placement increases the risk of introduced forb biomass, had negative impacts on all plant biomass and resulted in changes to community composition

• Long placements require longer vegetation recovery times; placement on actively growing vegetation may impact vegetation recovery and resilience

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Considerations (Access Mat Study)

• While direct heavy equipment traffic in this study primarily impacted physical characteristics over vegetation, keep in mind that direct traffic was limited to 8 passes • What would be the physical/vegetation impacts for multiple passes?

• Though vegetation had shortest recovery time with limited mat placement (<6 weeks best), depending on construction this may not always be possible • Likely still favorable to place mats if expecting to have multiple passes of

heavy equipment • If limited passes, but long construction season and willing to live with soil

impacts there could be a situation where direct traffic is favorable over matting.

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Implications (Tower Study)

• High disturbance methods increased introduced forb biomass, bulk density and decreased soil organic matter

• Low disturbance methods had less influence on plant biomass or soil characteristics generally, but still had some impacts

• Use of access mats are a better choice compared to soil removal for mixedgrass prairie recovery

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Next Steps

• The University is currently compiling field data from 2017 assessments

• Soil microbial community analyses underway, results expected to be available later this year • Suspected implication is that soil texture should be determined

before access mat placement to assess whether access mat use may positively or negatively impact soil microbial communities and therefore ecosystem functioning.

• Work with University of Alberta around potential Best Management Practices to reduce impacts to vegetation, which would potential translate into reduced reclamation costs

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Acknowledgements

University of Alberta

• K.A. Thompson, K. James, F. Najafi, • Dr. C.N. Carlyle, S. Quideau, and E.W. Bork

• Dr. Irving (University of Alberta) and numerous field assistants:• Christian Kentz, Megan O’Neill, Leah Rodvang, Lysandra Pyle

ATCO Electric

• Erin Donovan

• EATL Project Staff

• Executive Support

NSERC

• Funding support

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Thank you

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