Karine Pigeon, Doug MacNearney, Tracy McKay, and Laura Finnegan, fRI Research
March 31, 2017
Executive Summary
Seismic lines are one of the most pervasive anthropogenic disturbances in caribou ranges, with over 85,000km in west-central Alberta and Chinchaga caribou ranges. Building on previous work, we used field-based measurements of seismic line regeneration (tree and understory species abundance and occurrence), and animal use (tracks and signs, and camera traps), in combination with field and GIS-derived variables to identify seismic lines that 1) are following a trajectory towards natural recovery, and 2) have attributes associated with a high probability of use by alternate prey and predators. Our project was focused within the ranges of four west-central caribou herds: Little Smoky (LSM), A La Peche (ALP), Redrock Prairie Creek (RPC), and Narraway (NAR), and one north-west caribou herd: Chinchaga.
Using field data collected on occurrence and abundance of trees and understory species collected on seismic lines and in adjacent forest stands between 2013 and 2015, we found that trees were more likely to occur off seismic lines, and that generally, shrubs, forbs, graminoids were more likely to occur on seismic lines. We also found that large shrubs, and a number of forb and graminoid species were more abundant on seismic lines, although there were regional differences. Our models describing tree and understory species dissimilarity in relation to Geographic Information System (GIS) variables were poor, and we were therefore unable to create maps showing areas that are following a trajectory towards natural recovery (i.e. seismic lines that are highly similar to the adjacent forest stand) versus seismic lines that might need active restoration. Nevertheless, individual species models built using data collected on seismic lines demonstrated that large woody shrubs (alder, willow, gooseberry, and birch), sedges, fireweed, clover, and graminoids were more abundant in wetter areas and on North/South orientated seismic lines. Using the results of vegetation species-specific models, we mapped the probability of occurrence and abundance of species on seismic lines across the five herd ranges. We identified 7,884km (18%) of seismic lines with high birch abundance in Chinchaga, 391km (9%) of seismic lines with high gooseberry abundance in RPC/NAR, 210km (5%) of seismic lines with high graminoid species abundance in RPC/NAR, 1,966km (15%) of seismic lines with high sedge abundance in LSM/ALP, and 199km (1.6%) of seismic lines with high clover abundance in LSM/ALP. Based on occurrence models, we also identified 2,152km (55%) of seismic lines with a high probability of alder occurrence in RPC/NAR, 909km (7%) of seismic lines with a high probability of willow occurrence in LSM/ALP, and 452km (3.5%) of seismic lines with a high probability of fireweed occurrence in LSM/ALP.
Using a combination of tracks and signs data collected on seismic lines during summer (all five herds), and camera traps deployed on seismic lines year-round (west-central herds only), we assessed relationships between seismic line attributes (depth to water, LiDAR measurements of regeneration height, soil type, etc.) and wildlife use of seismic lines. For alternate prey (deer, moose, and elk) we found that use of seismic lines increased in areas with more early seral stage habitat types such as cutblocks, young forest stands, and wellsites. Detection of alternate prey on seismic lines was also partly explained by the abundance and occurrence of vegetation growing on seismic lines (higher detection with less alder and more graminoids). For predators, we found that bears were more likely to use seismic lines with more vegetation cover and more signs of moose, while lynx and wolves used seismic lines with less vegetation cover. Black bears also occurred more on seismic lines with less alder, while lynx and wolves were detected more on seismic lines with low vegetation heights. Using these results, we mapped the probability of occurrence of alternate prey and predators across west-central Alberta range and identified 10,596km of seismic lines with high probability of use by deer, 584km of seismic lines with high probability of use by elk, and 7,035km of seismic lines with high probability of use by bear species.
Based on our findings, we then overlaid spatially explicit maps of vegetation occurrence and abundance, and wildlife use. The resulting maps identify seismic lines with the highest probability of ‘undesirable’ species abundance and occurrence, the highest probability of alternate prey use, and seismic lines where high ‘undesirable’ vegetation species abundance and occurrence, and high probability of alternate prey use overlap. Using this approach, we classified 146km (0.9%) of seismic lines as very high, and 2,570km (17%) as high priority for restoration based on the probability of overlap between alternate prey and undesirable species. In Chinchaga, we identified 13,219km (25%) of seismic lines as very high priority for restoration based on the occurrence and abundance of undesirable species. By identifying seismic lines in west-central caribou ranges and the Chinchaga caribou range that have a high occurrence and abundance of ‘undesirable species’ the resulting maps can be used to target and prioritize restoration efforts towards seismic lines where natural regeneration is not occurring, and where active tree planting may be required to effectively restore seismic lines to reflect the composition of the adjacent forest. In addition, by linking seismic line attributes (vegetation height and species composition, soil type, and wetness) to the use of seismic lines by alternate prey and predators, the results of this project can also be used to prioritize restoration efforts towards reducing the distribution of alternate prey within caribou ranges, and thus reducing the attractiveness of seismic lines to predators of alternate prey (i.e. wolves and bears) and reduce caribou predation risk. Ultimately the priority lines for restoration identified from this project can be combined with priority lines for restoration identified from our previous work to focus restoration efforts and minimise the overlap between caribou and predators, decrease the use of seismic lines by alternate prey, and focus tree planting to seismic lines that are not naturally regenerating.
Related Paper in Environmental Management
# 16-ERPC-01