Decadal Assessment Of Successional Development On Reclaimed Upland Boreal Well Sites

• Author / Creator

  Frerichs, Laurie Anne

• Achieving forest recovery on previously forested well sites in northern Alberta is an on-going challenge for the oil and gas industry. Thirty-three experimental oil sands exploration (OSE) sites were constructed and reclaimed between 2004 and 2006 in northeastern Alberta. Our goal was to determine what factors or combination of factors in the construction, storage, and reclamation phases of development may deter or promote successional development toward pre-disturbance site conditions. Treatments included low (no soil disturbance) and varying degrees of higher disturbance via soil excavation and storage, woody material application and planting treatments during reclamation. Survival and growth of planted Picea glauca (Moench) Voss (white spruce) were compared between treatments. Soil chemical and physical properties were compared between treatments, and between treatments and forested controls. Naturally regenerating trees and plant communities were compared between treatments, forested controls, and cutblocks within the study area that were harvested in 2004. Statistical methods included ANOVA, orthogonal contrasts, ordination analyses using non-metric dimensional scaling, and indicator species analysis. Disturbance intensity of OSE treatments and treatment combinations in this study can be characterized and categorized by their degree of impact to aspen regeneration density, similarity in species composition to forested controls, and physical similarity of vegetative regrowth to cutblocks, including development of the tree canopy relative to the grass and shrub understory. Little difference was found in survival and growth of planted spruce, though response tended to be better where soil mixing had occurred. Aspen regeneration density decreased with increasing soil disturbance. Low disturbance methods that used whole slash as a reclamation tool resulted in similar plant species composition to forested controls, and similarity of plant community characteristics to cutblocks including aspen regeneration density. Low disturbance construction that left mulch covering the soil surface appeared to alter plant communities by reducing aspen regeneration, deterring native forb regeneration, and was prone to invasion by non-native plant species. Mulch retention also resulted in greater spruce and Populus balsamifera L (balsam poplar) densities, and lower Betula papyrifera Marsch (paper birch) density relative to low disturbance sites treated with whole slash. High forest soil disturbance resulted in greater alteration of plant communities, further reduced aspen regeneration density, and had high competitive grass and shrub cover which may prevent successful forest reestablishment. Species diversity and tree regeneration density were increasingly reduced by soil surface area exposure during storage. High soil exposure during storage favored desiccation tolerant species. Duff stripping and root salvage treatments resulted in higher aspen cover and greater similarity to forested controls relative to the two-pass stripping treatment. Duff stripped areas tended to have higher grass cover, lower tree cover relative to grass and shrubs, and lower plant species diversity compared to other treatments. The root salvage method resulted in the highest plant species diversity, and greater similarity to forested controls relative to all but the duff stripping treatment. Windrowing rather than spreading of whole slash where soil surface area had greater exposure during storage tended to increase aspen and poplar regeneration density. Total cover of spruce and birch was greater in windrowed slash in the two-pass stripping treatment, relative to the spread slash treatment. Planting trees increased tree cover relative to grass and shrubs, and plant species richness and/or diversity in both low and high disturbance treatments. Calamagrostis canadensis (Michx) P Beauv (blue joint), Rubus idaeus L (red raspberry), and Salix sp. had a stronger affinity for the non-planted treatments. Sites constructed with low disturbance and treated with whole slash appeared to have the greatest likelihood of prompt return to fully forested, intact boreal forest communities and therefore are the preferred construction method for ecological recovery. However, the root salvage method may be preferable where excavation is deemed necessary for site construction.

• Subjects / Keywords

  • Boreal
  • Reclamation
  • Forest succession
  • Woody debris
  • Excavation
  • Soil pile

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3KD1QZ0W

• 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.