Restoration of foothills rough fescue grassland following pipeline disturbance in southwestern Alberta

Response of grizzly bears (Ursus arctos) to pipelines in Alberta

This research provides the first in-depth analysis of fine-scale grizzly bear habitat selection and movement patterns in response to the linear footprints cleared for below-ground pipelines in Alberta. Using an extensive set of GPS location data from collared grizzly bears, we were able to determine that grizzly bears selected for younger pipelines (mean age since last construction~6.5 years), which are known to have a greater abundance of important bear foods. Bears also selected for wider corridors that were disturbed for construction more than once. During the spring season, sex/age class was an important predictor of grizzly bear use of pipelines, with adult female bears more likely to use these features than other sex/age classes. Examination of movement patterns revealed that pipeline density influenced grizzly bears' movement rates and path straightness, particularly in the spring, when bears moved more slowly and movement paths were more tortuous in areas with higher pipeline densities. These movement patterns are consistent with foraging behavior and further indicate that bears are not exhibiting avoidance behaviors or displacement by pipeline features, and pipelines may be functioning as seasonally important foraging areas for grizzly bears in Alberta.

Monitoring the Structure of Regenerating Vegetation Using Drone-Based Digital Aerial Photogrammetry

Measures of vegetation structure are often key within ecological restoration monitoring programs because a change in structure is rapidly identifiable, measurements are straightforward, and structure is often a good surrogate for species composition. This paper investigates the use of drone-based digital aerial photogrammetry (DAP) for the characterization of the structure of regenerating vegetation as well as the ability to inform restoration programs through spatial arrangement assessment. We used cluster analysis on five DAP-derived metrics to classify vegetation structure into seven classes across three sites of ongoing restoration since linear disturbances in 2005, 2009, and 2014 in temperate and boreal coniferous forests in Alberta, Canada. The spatial arrangement of structure classes was assessed using land cover maps, mean patch size, and measures of local spatial association. We observed DAP heights of short-stature vegetation were consistently underestimated, but strong correlations (rs > 0.75) with field height were found for juvenile trees, shrubs, and perennials. Metrics of height and canopy complexity allowed for the extraction of relatively tall and complex vegetation structures, whereas canopy cover and height variability metrics enabled the classification of the shortest vegetation structures. We found that the boreal site disturbed in 2009 had the highest cover of classes associated with complex vegetation structures. This included early regenerative (22%) and taller (13.2%) wood-like structures as well as structures representative of tall graminoid and perennial vegetation (15.3%), which also showed the highest patchiness. The developed tools provide large-scale maps of the structure, enabling the identification and assessment of vegetational patterns, which is challenging based on traditional field sampling that requires pre-defined location-based hypotheses. The approach can serve as a basis for the evaluation of specialized restoration objectives as well as objectives tailored towards processes of ecological succession, and support prioritization of future inspections and mitigation measures.

Access Matting Reduces Mixedgrass Prairie Soil and Vegetation Responses to Industrial Disturbance

Substantial interest exists in understanding the role of low-disturbance construction methods in mitigating industrial impacts to native grassland soils and vegetation. We assessed soil and vegetation responses to conventional high-disturbance sod-stripping and revegetation on sandy soils, and the alternative practice of low-disturbance access matting to provide a temporary work surface on sandy and loamy soils. Treatments were associated with high-voltage transmission tower construction during 2014 within the Mixedgrass Prairie. High-disturbance sites were hydroseeded in May of 2015, while low-disturbance sites recovered naturally. We assessed soil physical (bulk density, water infiltration) and chemical properties (organic matter, pH, and electrical conductivity) after construction and herbage biomass for three growing seasons. Sod-stripping led to 53% greater soil bulk density and 51% less organic matter than nondisturbed controls, while water infiltration increased by 32% in these high-sand (>80%) soils. In contrast, access matting led to minimal soil property changes regardless of the texture. While total herbage biomass was unaffected by all construction treatments, sod-stripping reduced grass biomass by 80% during the first growing season, which coincided with a 119% increase in forb mass. Root biomass (0-15 cm) also declined 77% with sod-stripping. Vegetation biomass on sites with access matting remained largely unaffected by the disturbance. Overall, low-disturbance construction methods using access matting were more effective than sod-stripping in mitigating the negative impacts of industrial development on Mixedgrass soil properties, as well as vegetation biomass, and are recommended as a best management practice during industrial disturbance.

Change in plant species composition on powerline corridor: a case study

Clear-cutting of powerline corridors (PLCs) adversely affects ecosystem function by fragmenting intact forests and supports biodiversity with the development of a structurally diverse vegetation. The study aimed to determine diversity and composition caused by clear-cutting and monitor change in species composition on the PLC passing through Research Forest of IUC Faculty of Forestry. Species composition was monitored in 10 permanent plots on the clear-cut area (over 3 years) paired on the forest edge (over 2 years) and forest interior (first year). Diversity, the cover of invasive plants, and life form traits of the sample plots were compared. Change in species composition with time was determined with redundancy analysis (RDA) for repeated measures using CANOCO 5. Open-site conditions caused by clear-cutting promoted the number of hemicryptophyte and therophyte life forms which resulted in a high species richness on the clear-cut area (167 species), followed by forest edge (117 species) and forest interior (60 species). However, species richness which showed a peak in the second year was decreased at the end of 3 years. Total cover of invasives was considerably higher on the clear-cut area (23%) compared with the forest (3.78%) and did not make a significant effect on forest interior species in narrow corridors. Clear-cutting combined with slash piling promoted the undesired vertical development of tree sprouts and Robinia pseudoacacia which shortened management rotation in a short period. However, sites dominated by shrubs such as Cistus creticus and Cistus salviifolius suppressed the development and invasion of undesirable trees.

The effects of pipeline construction disturbance on soil properties and restoration cycle

Disturbance to the physical-chemical properties of soil caused by pipeline installation was evaluated using two soil quality indices to identify the scale of disturbance and the restoration cycle. The integrated soil quality index (SQI) was used to evaluate soil property changes in different pipeline zones (0, 10, 20, and 50 m from the pipeline) at sites 1 and 2. The soil restoration index (SRI) was used to estimate soil recovery from three pipelines with different recovery periods (2, 6, and 8 years) at site 3. The results showed that the adverse effects of pipeline construction on soil properties mainly occurred in the right-of-way (ROW) areas and the impaired zones were in the order trench > piling and working areas > 20 and 50 m. The soil restoration cycle may be complete within 6 years of construction. At site 3, the SRI in the ROW area of a pipeline after 6 years of restoration was close to 100 %, showing full soil recovery. However, the SRI in the disturbed areas of a pipeline after 2 years of restoration was much lower than that after 6 years of restoration, indicating that the soil was still recovering from the disturbance. The topography may change the intensity of disturbance in different areas due to the movement patterns of heavy machinery and traffic routes. There were local variations in the SQI within the pipeline zones, with flat areas suffering greater disturbance than hilly areas, indicating that topography should be considered in a pipeline's environmental impact assessment.