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Data from: Ecosystem memory of wildfires affects resilience of boreal mixedwood biodiversity after retention harvest
Bergeron, J.A. Colin; Pinzon, Jaime; Odsen, Sonya; Bartels, Samuel; Macdonald, S. Ellen; Spence, John R.; Bergeron, J. A. Colin — 2017-05-19 The extent to which past states influence present and future ecosystem characteristics (ecosystem memory (EM)) is challenging to assess because signals of past ecological conditions fade with time. Using data about seven different taxa, we show that ecological gradients initiated by wildfires up to three centuries earlier affect biotic recovery after variable retention harvest in the boreal mixedwood forest. First, we show that fire history over the last 300 years is reflected in pre-harvest species-specific stand basal area (BA), with longer times since high severity fire associated with proportionally higher BA of shade-tolerant softwood species than shade-intolerant hardwoods. Second, using patterns in the BA of pre-harvest tree species we link fire history to species composition of pre-harvest assemblages of bryophytes, herbs, shrubs, regenerated trees, songbirds, spiders and carabid beetles. Finally, we use variance partitioning to compare the importance of species-specific pre- versus post-harvest BA for explaining the structure of these seven biotic assemblages two, five and ten years after harvest. We detected persistent significant effects of pre-harvest BA in all post-harvest biotic assemblages up to ten years after harvest. Pre-harvest BA was more strongly associated with early post-harvest understory plant and carabid beetle assemblages than was post-harvest BA, but the opposite was true for spiders, songbirds and regenerated trees. EM effects were detected two, five and ten years after harvest but temporal patterns varied according to taxa. Thus, EM of fire history can persist at least ten years after variable retention harvest and such effects appear to be stronger for understory plants than for animals. We conclude that management of biological legacies to increase post-disturbance EM will increase overall resilience and sustainability of these mixedwood forests.
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Data from: Ten-year responses of ground-dwelling spiders to retention harvest in the boreal forest
Pinzon, Jaime; Spence, John R.; Langor, David W.; Shorthouse, David P. — 2016-06-08 The Ecosystem Management Emulating Natural Disturbances (EMEND) project tests the hypothesis that varying levels of green tree retention maintain and retain forest biodiversity better than conventional clear-cutting. We studied epigaeic spiders to assess biodiversity changes two, five and ten years following a range of partial retention harvests (clear-cut, 10-75% retention) and unharvested controls in four boreal mixedwood cover-types. A total of 56, 371 adult spiders representing 220 species was collected using pitfall traps. Lasting effects on forest structure were proportional to harvest intensity. These changes strongly influenced spider richness, abundance and species composition, as well as assemblage recovery. Distinctive assemblages were associated with disturbance level, especially with partial harvests (≤50% retention), and these were dominated by open-habitat species even ten years after harvest. Assemblages were more similar to those of controls in the highest (75%) retention treatment, but significant recovery toward the structure of pre-disturbance assemblages was not detected for any prescription in any cover-type. Although early responses to retention harvest suggested positive effects on spider assemblages, these are better explained as lag effects after harvest because assemblages were less similar to those of unharvested controls five years post-harvest, and only minor recovery was observed ten years following harvest. Retention of forest biodiversity decreased over time, especially in conifer stands and the lower (10-50%) retention treatments. Overall, retention harvests retained biodiversity and promoted landscape heterogeneity somewhat better than clear-cutting; however, there was a clear gradient of response and no retention ‘threshold’ for conservation can be recommended on the basis of our data. Furthermore, results suggest that retention harvest prescriptions should be adjusted for cover-type. We show that low retention ameliorated impacts in broadleaved forests characteristic of earlier stages in mixedwood succession, but only higher retention was associated with less impact in successionally older conifer forests. Although these short-term responses (10 years) of spider assemblages support use of retention harvests, understanding the true conservation merit of these practices, relative to conventional approaches, requires evaluation over longer time scales, with work more focused on recovery of biodiversity than on its preservation after harvest.
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Biodiversity and Forest structure one year following the 2016 Fort McMurray (Alberta) fire event
Pinzon, Jaime; Dabros, Anna; Riva, Federico; Glasier, James — 2020-10-09 <p>Exploration practices for oil sands developments in the boreal forest of western Canada create a network of thousands of kilometers of linear features, particularly seismic lines that dissect these forests posing significant environmental challenges. As wildfire is one of the prevalent stand-replacing natural disturbances in the Canadian boreal forest, it is an important driver of environmental change and stand development that may contribute to the mitigation of such linear industrial footprint. Here, we evaluate the short-term cumulative (also known as combined) effects of seismic lines and wildfire on biodiversity and site conditions. One year after the Horse River (Fort McMurray, Alberta) fire event in the spring of 2016, we compared dissected and undisturbed forests in burned and unburned boreal peatlands, assessing changes in overall stand structure and the responses of a variety of organisms. Soil moisture was significantly higher on seismic lines than in the adjacent forest, suggesting why most of the study sites within the fire perimeter showed little evidence of burning at the line in relation to the adjacent forest. Low fire severity on seismic lines seemed an important driver of local species diversity for ants, beetles, spiders, and plants in disturbed peatlands, resulting in similar species composition on seismic lines both within and outside the burned area, but different assemblages in burned and unburned adjacent forests. Our results suggest that fire did not erase seismic lines; rather, wildfire might increase the influence of this footprint on the recovering adjacent forest. Longer term monitoring will be necessary to understand how boreal treed peatlands respond to the cumulative effect of wildfire and linear disturbances.</p> https://creativecommons.org/publicdomain/zero/1.0/
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Ground-dwelling invertebrates and plants following the application of inverted soil mounding on seismic lines
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Pinzon, Jaime; Dabros, Anna — 2023-10-23 <p><span lang="EN-US">In northern Alberta, Canada, much of treed boreal peatlands are fragmented by seismic lines – linear disturbances where trees and shrubs are cleared for the exploration of fossil fuel reserves. Seismic lines have been shown to have slow tree regeneration, likely due to the loss of microtopography during the creation of seismic lines. Inverted soil mounding is one of the treatments commonly applied in Alberta to restore seismic lines and to mitigate the use of these corridors by wildlife and humans. In 2018, we assessed the effects of mounding on understory plants and arthropod assemblages, three years after treatment application. We sampled in five mounded and five untreated seismic lines, and in their adjacent treed fens (reference fens) within the <span lang="EN-US">Canadian Natural Resources Ltd (CNRL) Kirby South in-situ steam-assisted gravity drainage (SAGD) Plant, in the Athabasca oil sands (55°22'37.2" N, 111°10'3" W) of NW Alberta</span>. Here we provide the species composition at these sites.</span></p>
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Data from: Fine-scale forest variability and biodiversity in the boreal mixedwood forest
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Pinzon, Jaime; Wu, Linhao; He, Fangliang; Spence, John R. — 2017-07-12 Local spatial variation in species distributions is driven by a mix of abiotic and biotic factors, and understanding such hierarchical variation is important for conservation of biodiversity across larger scales. We sought to understand how variation in species composition of understory vascular plants, spiders, and carabid beetles is associated with concomitant spatial variation in forest structure on a 1-ha permanent plot in a never-cut mixedwood forest in central Alberta (Canada). Using correlations among dendrograms produced by cluster analysis we associated data about mapped distribution of all living and dead stems > 1 cm diameter at breast height with distributions of the three focal taxa sampled from regular grids across the plot. Variation in each of these species assemblages were significantly associated with several forest structure variables at various spatial scales, but the scale of the associations varied among assemblages. Variation in species richness and abundance was explained mostly by changes in basal area of trees across the plot; however, other variables (e.g., snag density and tree density) were also important, depending on assemblage. We conclude that fine-scale habitat variation is important in structuring spatial distribution of the species of the forest floor, even within a relatively homogeneous natural forest. Thus, assessments that ignore within-stand heterogeneity and management that ignores its maintenance will have limited utility as conservation measures for these taxa, which are major elements of forest biodiversity.
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Rapid recovery of boreal rove beetle (Staphylinidae) assemblages 16 years after variable retention harvest
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Lee, Seung-Il; Langor, David; Spence, John; Pinzon, Jaime; Pohl, Gregory; Hartley, Dustin; Work, Timothy; Wu, Linhao — 2022-11-07 <p>Post-harvest recovery<span lang="EN-US"> of biodiversity is one of the important goals in modern forestry. A variable retention (VR) approach has been of particular interest in North America because it promotes rapid faunal recovery while </span>minimizing the negative lasting impacts of logging on the natural fauna. <span lang="EN-US">We studied responses of </span>rove beetles (Coleoptera: Staphylinidae) to a broad range of retention harvests (2, 10, 20, 50, and 75 % retention) in comparison to uncut controls as part of the <span lang="EN-US">Ecosystem Management Emulating Natural Disturbance (EMEND) experiment in the boreal mixedwood forest of western Canada. We sampled beetles using pitfall traps 1, 2, 11, and 16 years post-harvest in replicated (n=3) stands representing four cover types (deciduous-dominated, deciduous with spruce understory, mixed, and coniferous-dominated). We collected</span> 74,263 individuals distributed across 99 species (excluding Aleocharinae). <span lang="EN-US">Estimated species richness was highest in clear-cuts until year 11, but by year 16 species richness was similar among treatments. Species composition initially varied strongly in relation to the intensity of harvest treatments, but overall variation decreased with time</span>, and by year 16, species composition overlapped among most treatment combinations. Assemblages recovered more quickly in <span lang="EN-US">early successional (deciduous-dominated) </span>than in <span lang="EN-US">late successional (</span>mixed and <span lang="EN-US">conifer-dominated) stands. Overall, our results show that rove beetle assemblages in stands harvested to all VR prescriptions converged more rapidly toward those in fire-origin mature stands than did assemblages in clear-cuts over the first 16 years post-harvest. Thus, it demonstrates that even modest levels of forest retention can facilitate the recovery of staphylinid assemblages in managed landscapes.</span></p>

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(auteur : Pinzon, Jaime)

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