Impacts of a six year old pipeline right of way on Halimolobos virgata (Nutt.) O.E. Schulz (slender mouse ear cress), native dry mixedgrass prairie uplands, and wetlands

• Author / Creator

  Low, Caitlin H.

• Reclamation of native prairie ecosystems is of growing importance as they continue to be impacted by anthropogenic disturbances. Since European settlement, Alberta grasslands have declined by 61 %. Grasslands are agriculturally important, act as a carbon sink, and many species depend upon them. In Alberta, 77 % of flora and fauna species at risk depend upon or are endemic to native grasslands. Environment Canada recommends a 300 m set back between at risk species, their critical habitat, and pipeline disturbances. Pipeline disturbances can fragment habitat, introduce non native species, impact the soil through admixing and compaction, and alter hydrologic regimes. The impact of pipeline disturbance on at risk plant species and critical habitat is not widely documented or understood. The objective of this research was to assess the impact of a six year old pipeline right of way on the rare species Halimolobos virgata and native dry mixedgrass prairie upland and wetland ecosystems. Halimolobos virgata surveys were conducted at two native prairie sites with historic populations. Upland vegetation assessments were conducted at ten locations relative to the pipeline right of way at six native prairie sites. Wetland vegetation assessments were conducted at eight sites on and nine sites off the right of way in native prairie. The research was conducted in southern Alberta, 150 km north of Medicine Hat, over two field seasons in 2014 and 2015. Halimolobos virgata increased in population size over two field seasons. It appeared to select microhabitat sites with limited competition from other species and a high amount of litter cover. Halimolobos virgata was found on the pipeline trench in the last year of the study. Impacts to the plant community were greatest over highest disturbance zones of the right of way, the trench and work areas. Species richness and diversity were significantly lower in these areas relative to other right of way zones and undisturbed prairie. The trench had greatest bare ground and least live species cover. Little variability was found in wetlands on and off the right of way. Community composition, species richness, diversity, similarity, and ground cover were consistent across all sites. After seven growing seasons, the impacts of disturbances caused by pipeline right of ways have begun to lessen on the plant communities of uplands and wetlands. Native species were dominant, and non native species did not appear to be dominating any areas of the right of way. Halimolobos virgata does not appear to be negatively impacted by the right of way, thus the 300 m set back is not required, provided similar construction methods are used. The set back of 30 m between Halimolobos virgata and pipeline construction that was used by TransCanada is sufficient to protect existing populations and associated habitat.

• Subjects / Keywords

  • Pipelines
  • Rare species
  • Halimolobos virgata
  • Wetlands
  • Reclamation
  • Disturbance
  • Dry mixedgrass prairie

• Graduation date

  Spring 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R39W0991V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.