Ungulate occurrence in forest harvest blocks is influenced by forage availability, surrounding habitat and silviculture practices

Abstract

Forest harvesting causes habitat loss and alteration and can change predator–prey dynamics. In Canada, forest harvesting has shifted the distribution and abundance of ungulates (deer, elk and moose) that prefer early seral forest, resulting in unsustainable caribou predation by shared predators (bears, cougars and wolves). Long‐term solutions for caribou recovery require management to reduce ungulate prey species within caribou ranges. Silviculture practices applied after forest harvesting directly affect the amount of forage available in harvested areas, and therefore influence ungulate distribution, but few studies have completed detailed assessments on how specific treatments of site preparation, planting and stand tending influence ungulate use of harvest blocks. We used camera traps, silviculture data, GIS‐derived habitat and disturbance data, and detailed vegetation data collected at field sites to investigate ungulate occurrence in harvest blocks in west‐central Alberta, Canada. We compared seasonal ungulate occurrence and investigated how site‐specific characteristics, the surrounding habitat and disturbance density, and fine‐scale silviculture treatments influenced ungulate occurrence in blocks. Deer, elk and moose occurrence was higher in summer compared to winter. Elk, moose and white‐tailed deer occurrence was higher in blocks with greater availability of specific forage species. Moose occurrence was higher in blocks with a lower road density in the surrounding area, and white‐tailed deer occurrence was higher in blocks further from seismic lines and with a lower proportion of harvest blocks in the surrounding area. Deer, elk and moose occurrence was higher in younger harvest blocks. Mule deer and white‐tailed deer occurrence was lower in blocks with higher planting densities of lodgepole pine, and mule deer occurrence was also lower in blocks that had been stand tended. Our study provides detailed information on ungulate response to fine‐scale silviculture methods used in Alberta, directly linking wildlife occurrence to forestry practices, and providing practical scientific information to inform sustainable forestry. Translating this research into practical landscape management decisions could benefit boreal biodiversity, including threatened species like caribou, and culturally and economically important species like deer, elk and moose.

Whose line is it anyway? Moose (Alces alces) response to linear features

“…During winter, as previously mentioned, pipelines likely offer less shelter, cover, and forage available above the snowpack than seismic lines, which is likely driving winter moose selection for pipelines only when other linear features are not available to them. At the fine scale, we found that moose were indifferent to pipelines regardless of the surrounding habitat or underlying soil wetness but that there were differences among individuals, and therefore, like seismic lines and harvest blocks, moose use of pipelines is most likely linked to finer scale characteristics like vegetation composition, lateral cover, and the presence of game trails (McKay & Finnegan, 2023;Tattersall et al, 2023).…”

“…During summer, the width of pipelines combined with ongoing vegetation management may result in pipelines having similar thermal cover, but less forage availability than harvest blocks and wildfires, making pipelines less attractive to moose when harvest blocks and wildfires are available. Moose use of harvest blocks and pipelines during summer is linked to the availability of shrubs and lateral cover (McKay & Finnegan, 2023;Tattersall et al, 2023); pipelines are periodically cleared to maintain line-of-sight (Alberta Energy Regulator, 2016;MacDonald et al, 2020), while with the exception of mechanical or chemical stand tending a few years after planting, harvest blocks are left to regenerate. Therefore, harvest blocks and areas that are naturally regenerating after wildfires are likely more attractive sources of shrub and sapling moose forage than maintained pipelines with graminoids and clover less preferred by moose (MacDonald et al, 2020;McKay & Finnegan, 2023;Tattersall et al, 2023).…”

“…Moose use of harvest blocks and pipelines during summer is linked to the availability of shrubs and lateral cover (McKay & Finnegan, 2023;Tattersall et al, 2023); pipelines are periodically cleared to maintain line-of-sight (Alberta Energy Regulator, 2016;MacDonald et al, 2020), while with the exception of mechanical or chemical stand tending a few years after planting, harvest blocks are left to regenerate. Therefore, harvest blocks and areas that are naturally regenerating after wildfires are likely more attractive sources of shrub and sapling moose forage than maintained pipelines with graminoids and clover less preferred by moose (MacDonald et al, 2020;McKay & Finnegan, 2023;Tattersall et al, 2023). During winter, as previously mentioned, pipelines likely offer less shelter, cover, and forage available above the snowpack than seismic lines, which is likely driving winter moose selection for pipelines only when other linear features are not available to them.…”

Logging, linear features, and human infrastructure shape the spatial dynamics of wolf predation on an ungulate neonate

“…Young harvest areas in the GVE are primarily composed of regenerating deciduous trees and dense understory vegetation (primarily aspen), which probably provide ideal forage conditions for adult deer and hiding cover for fawns (Courtois et al, 2002; Rohm et al, 2007). Indeed, studies from other parts of the boreal forest have demonstrated that deer often select for recently‐harvested areas during summer (Lesage et al, 2002; McKay & Finnegan, 2023). Although these patches of high‐quality habitat may have benefits for both adult and neonatal ungulates, wolves appear to exploit deer concentrated in them.…”