Allison Pamela Yataco, Sabina Noor, Miguel Montoro Girona, Timothy Work, Emma Despland. Limited Differences in Insect Herbivory on Young White Spruce Growing in Small Open Plantations and under Natural Canopies in Boreal Mixed Forests 2024. Insects 196
DOI : 10.3390/insects15030196
In managed boreal forests, both plantations and natural regeneration are used to re-establish a cohort of conifer trees following harvest or disturbance. Young trees in open plantations generally grow more rapidly than under forest canopies, but more rapid growth could be compromised by greater insect damage. We compared insect damage on white spruce (Picea glauca (Moench) Voss, Pinaceae) growing in plantations with naturally regenerated trees under mature forest canopies in boreal forests (Québec, Canada). We selected ten sites in the naturally regenerated forest and in small, multispecies plantations and sampled ten young trees of 2.5–3 m (per site) in late summer 2020 and again in early and late summer 2021. We compared overall rates of herbivory, galls (adelgids), damage by the spruce budworm (Choristoneura fumiferana, Clemens), and defoliation from sawflies. Overall, insect herbivory damage remained at similarly low levels in both habitats; an average of 9.3% of expanding shoots were damaged on forest trees and 7.7% in plantation trees. Spruce budworm damage increased from 2020 to 2021 and remained higher in under-canopy trees, but damage rates were negligible at this early stage of the outbreak (1.5% in forest vs. 0.78% of buds damaged on plantation trees). While damage due to galls was higher in plantations, the overall low level of damage likely does not pose a significant impact on the growth or mortality of young trees.
Marion Noualhaguet, Timothy Work, Maxence Soubeyrand, Nicole J. Fenton. Twenty-year recovery of managed stand, in structure and composition, in boreal mixedwood stands of northwestern Quebec 2023. Can. J. For. Res. 478
DOI : 10.1139/cjfr-2022-0309
The natural disturbance-based management (NDBM) aims to maintain specific structural and compositional attributes of natural forests in managed stands. Operationally, NDBM relies on diversifying and adapting silvicultural practices, including partial harvesting (PC), to expand the range of options beyond that of simply clearcuts (CC).
Marion Noualhaguet, Timothy Work, Maxence Soubeyrand, Nicole J. Fenton. Bryophyte community responses 20 years after forest management in boreal mixedwood forest. 2023. For. Ecol. Manage.
DOI : 10.2139/ssrn.4292682
Sustainable forest management relies on a diversity of harvesting practices to conserve the variety of stand structures and compositions found in natural forests. Extensive use of clearcuts can homogenize stand structure by removing all the canopy, damage forest soils and destroy older downed woody debris already present within stands. In contrast partial cuts maintain some standing overstory and conserve certain biological legacies like large live trees as well as standing and downed dead wood, and thus should better conserve biodiversity. However, given the large number of species potentially affected by harvest operations, balancing harvesting intensity and conservation of biodiversity requires a clear understanding of habitat requirements of resident organisms and species conservation post-harvest. We examined the impacts of increasing intensities of stem removal (33%, 40%, 66% and 100%) 20 years after harvest on bryophyte communities in three stand types common in the succession sequences of Eastern boreal mixedwood forests that were dominated by trembling aspen, mixedwood and conifers. While many generalist and common forest species were shared among all harvesting levels and forest types, more specialized species like liverworts differed strongly between uncut and clearcut stands. However, liverworts and other specialists differed less between uncut and partial cut stands. Bryophyte species in hardwood dominated stands tolerated more fluctuations in environmental conditions than species in mixed stands. We were unable to find habitat specialists typically associated with coniferous stands and may be related to prior outbreaks of spruce budworm that occurred 30 years ago. Our results highlight how harvest intensity and forest stand type interact to affect bryophytes and how intact stands may be required to conserve many species that are sensitive to any degree of harvesting.
Marion Noualhaguet, Benoit Lafleur, Nicole J. Fenton, Timothy Work. Résistance et résilience des peuplements forestiers en réponse à différentes intensités de coupe en forêt boréale. 2021. Le Couvert Boréal p.26
Christoforos Pappas, Yves Bergeron, Nicolas Bélanger, Han Y. H. Chen, Philip G. Comeau, Sylvain Delagrange, Olivier Blarquez, Amanda Diochon, Loïc D’Orangeville, Pierre Drapeau, Louis Duchesne, Elise Filotas, Fabio Gennaretti, Benoit Lafleur, Louis De Grandpré, Annie DesRochers, David Langor, François Lorenzetti, Charles Nock, Daniel Houle, Miguel Montoro Girona, Christian Messier, Barb R. Thomas, Simon Lebel Desrosiers, Rongzhou Man, Timothy Work, Daniel Kneeshaw. Smartforests Canada: A Network of Monitoring Plots for Forest Management Under Environmental Change. 2021. Climate-Smart Forestry in Mountain Regions 521-543
DOI : 10.1007/978-3-030-80767-2_16
Monitoring of forest response to gradual environmental changes or abrupt disturbances provides insights into how forested ecosystems operate and allows for quantification of forest health. In this chapter, we provide an overview of Smartforests Canada, a national-scale research network consisting of regional investigators who support a wealth of existing and new monitoring sites. The objectives of Smartforests are threefold: (1) establish and coordinate a network of high-precision monitoring plots across a 4400 km gradient of environmental and forest conditions, (2) synthesize the collected multivariate observations to examine the effects of global changes on complex above- and belowground forest dynamics and resilience, and (3) analyze the collected data to guide the development of the next-generation forest growth models and inform policy-makers on best forest management and adaptation strategies. We present the methodological framework implemented in Smartforests to fulfill the aforementioned objectives. We then use an example from a temperate hardwood Smartforests site in Quebec to illustrate our approach for climate-smart forestry. We conclude by discussing how information from the Smartforests network can be integrated with existing data streams, from within Canada and abroad, guiding forest management and the development of climate change adaptation strategies.
Lauren Egli, Katherine LeVan, Timothy Work. Taxonomic error rates affect interpretations of a national-scale ground beetle monitoring program at National 2020. Ecosphere e03035
DOI : 10.1002/ecs2.3035
Abstract Parataxonomists are responsible for taxonomic identifications in large-scale biodiversity monitoring programs. However, they may lack formal taxonomic training, and thus, quantifying error rate in identification is paramount for evaluating data quality of larger biomonitoring efforts. In large-scale biomonitoring in particular, parataxonomist error rate could vary among regions with different species richness and composition. Here, we tested whether error rates in identification of ground beetles (Coleoptera: Carabidae) by parataxonomists increased in regions with greater species richness throughout the National
Zelin Liu, Changhui Peng, Jean-Noël Candau, Timothy Work, Louis De Grandpré, Xiaolu Zhou, Daniel Kneeshaw. Aerial spraying of bacterial insecticides to control spruce budworm
defoliation leads to reduced carbon losses. 2020. Ecosphere 11(1):e02988
DOI : 10.1002/ecs2.2988
Spruce budworm (SBW) outbreaks are a major natural disturbance in boreal forests of eastern North America. During large?scale infestations, aerial spraying of bacterial insecticides is used to suppress local high?density SBW populations. While the primary goal of spraying is the protection of wood volume for later harvest, it should also maintain carbon stored in trees. This study provides the first quantitative analysis of the efficacy of aerial spraying against SBW on carbon dynamics in balsam fir, spruce, and mixed fir–spruce forests. In this study, we used the TRIPLEX?Insect model to simulate carbon dynamics with and without spray applications in 14 sites of the boreal forest located in various regions of Québec. We found that the efficacy of aerial spraying on reducing annual defoliation was greater in the early stage (<5 yr since the outbreak began) of the outbreak than in later (5–10 yr since the outbreak began) stage. Our results showed that more net ecosystem productivity is maintained in balsam fir (the most vulnerable species) than in either spruce or mixed fir–spruce forests following spraying. Also, average losses in aboveground biomass due to the SBW following spraying occurred more slowly than without spraying in balsam fir forests. Our findings suggest that aerial spraying could be used to maintain carbon in conifer forests during SBW disturbances, but that the efficacy of spray programs is affected by host species and stage of the SBW outbreak.
Cédric Boué, Tonia DeBellis, Lisa Venier, Steven Kembel, Timothy Work. Limited initial impacts of biomass harvesting on composition of wood-inhabiting fungi within residual stumps. 2019. PeerJ 7:e8027
DOI : 10.7717/peerj.8027
Growing pressures linked to global warming are prompting governments to put policies in place to find alternatives to fossil fuels. In this study, we compared the impact of tree-length harvesting to more intensive full-tree harvesting on the composition of fungi residing in residual stumps 5 years after harvest. In the tree-length treatment, a larger amount of residual material was left around the residual stumps in contrast to the full-tree treatment where a large amount of woody debris was removed. We collected sawdust from five randomly selected residual stumps in five blocks in each of the tree-length and full-tree treatments, yielding a total of 50 samples (25 in each treatment). We characterized the fungal operational taxonomic units (OTUs) present in each stump using high-throughput DNA sequencing of the fungal ITS region. We observed no differences in Shannon diversity between tree-length and full-tree harvesting. Likewise, we observed few differences in the composition of fungal OTUs among tree-length and full-tree samples using non-metric multidimensional scaling. Using the differential abundance analysis implemented with DESeq2, we did, however, detect several associations between specific fungal taxa and the intensity of residual biomass harvest. For example, Peniophorella pallida (Bres.) KH Larss. and Tephromela sp. were found mainly in the full-tree treatment, while Phlebia livida (Pers.) Bres. and Cladophialophora chaetospira (Grove) Crous & Arzanlou were found mainly in the tree-length treatment. While none of the 20 most abundant species in our study were identified as pathogens we did identify one conifer pathogen species Serpula himantioides (Fr.) P. Karst found mainly in the full-tree treatment.
Anouschka R. Hof, Therese Löfroth, Jörgen Rudolphi, Joakim Hjältén, Timothy Work. Simulating long-term effects of bioenergy extraction on dead wood availability at a landscape scale in Sweden. 2018. Forests 9(8):457
DOI : 10.3390/f9080457
Wood bioenergy may decrease the reliance on fossil carbon and mitigate anticipated increases in temperature. However, increased use of wood bioenergy may have large impacts on forest biodiversity primarily through the loss of dead wood habitats. We evaluated both the large-scale and long-term effects of different bioenergy extraction scenarios on the availability of dead wood and the suitability of the resulting habitat for saproxylic species, using a spatially explicit forest landscape simulation framework applied in the Swedish boreal forest. We demonstrate that bioenergy extraction scenarios, differing in the level of removal of biomass, can have significant effects on dead wood volumes. Although all of the scenarios led to decreasing levels of dead wood, the scenario aimed at species conservation led to highest volumes of dead wood (about 10 m3 ha-1) and highest connectivity of dead wood patches (mean proximity index of 78), whilst the scenario aimed at reaching zero fossil fuel targets led to the lowest levels (about 8 m3 ha-1) and least connectivity (mean proximity index of 7). Our simulations stress that further exploitation of dead wood from sites where volumes are already below suggested habitat thresholds for saproxylic species will very likely have further negative effects on dead wood dependent species. © 2018 by the authors.
Zelin Liu, Changhui Peng, Jean-Noël Candau, Timothy Work, Annie DesRochers, Daniel Kneeshaw. Application of machine-learning methods in forest ecology: recent progress and future challenges. 2018. Environ. Rev. 26(4):339-350
DOI : 10.1139/er-2018-0034
L’apprentissage automatique, une branche importante de l’intelligence artificielle, est de plus en plus mis en application dans le domaine des sciences comme l’écologie forestière. Ici, nous examinons et faisons le point sur trois méthodes d’apprentissage automatique généralement utilisées incluant l’apprentissage par arbre de décision, le réseau de neurones artificiels et la machine à vecteurs de support, ainsi que leurs applications au niveau de quatre aspects différents de l’écologie forestière au cours de la dernière décennie. Ces applications incluent : (i) les modèles de répartition des espèces, (ii) les cycles de carbone, (iii) l’évaluation et la prédiction des dangers et (iv) d’autres applications en gestion forestière. Alors que les approches d’apprentissage automatique sont utiles au niveau de la classification, de la modélisation et de la prédiction en recherche dans le domaine de l’écologie forestière, le développement accru des technologies d’apprentissage automatique est limité par le manque de données pertinentes et le « seuil relativement plus élevé » des applications. Cependant, l’utilisation combinée d’algorithmes multiples et de communication et coopération améliorées entre les chercheurs en écologie et les concepteurs d’apprentissage automatique présente toujours des défis importants et des tâches en vue de l’amélioration de la recherche écologique à l’avenir. Nous laissons entendre que les applications futures d’apprentissage automatique en écologie deviendront un outil de plus en plus intéressant pour les écologistes face aux « données massives » et que les écologistes auront accès à plus de types de données tel que le son et la vidéo dans un proche avenir ce qui ouvrira probablement de nouvelles avenues en matière de recherche en écologie forestière. [Traduit par la Rédaction]
Sophie Laliberté, Alain Leduc, Pierre Drapeau, Nicole J. Fenton, Daniel Kneeshaw, Osvaldo Valeria, Yves Bergeron, Timothy Work. Commentaires de l’Institut de recherche sur les forêts et de la Chaire en aménagement forestier durable. 2018. Consultation sur le projet de stratégie nationale de production de bois MFFP 9 p.
À l’été 2018, le Ministère des forêts, de la faune et des parcs (MFFP) a tenu des consultations sur un projet de Stratégie nationale de production de bois. Dans ce document se trouvent les commentaires formulés aux noms de l’Institut de recherche sur les forêts (IRF) et de la Chaire en aménagement forestier durable (AFD). Ils sont structurés en fonction des questions contenues dans le formulaire fourni par le MFFP.
Klara Joelsson, Joakim Hjältén, Timothy Work. Uneven-aged silviculture can enhance within stand heterogeneity and beetle diversity. 2018. J Environ Manage 205:1-8
DOI : 10.1016/j.jenvman.2017.09.054
Uneven-aged silviculture may better maintain species assemblages associated with old-growth forests than clear felling in part due to habitat heterogeneity created by maintaining standing retention strips adjacent to harvest trails. Retention strips and harvest trails created at the time of tree removal will likely have different microclimate and may harbor different assemblages. In some cases, the resultant stand heterogeneity associated with uneven-aged silviculture may be similar to natural small-scale disturbances. For beetles, increased light and temperature as well as potential access to young vegetation and deadwood substrates present in harvset trails may harbor beetle assemblages similar to those found in natural gaps. We sampled saproxylic beetles using flight intercept traps placed in harvest corridors and retention strips in 9 replicated uneven-aged spruce stands in central Sweden. We compared abundance, species richness and composition between harvest corridors and retention strips using generalized linear models, rarefaction, permutational multivariate analysis of variance and indicator species analysis. Canopy openness doubled, mean temperature and variability in daily temperature increased and humidity decreased on harvest trails. Beetle richness and abundance were greater in harvests trails than in retention strips and the beetle species composition differed significantly between habitats. Twenty-five species were associated with harvest trails, including three old-growth specialists such as Agathidium discoideum (Erichson), currently red-listed. We observed only one species, Xylechinus pilosus (Ratzeburg) that strongly favored retention strips. Harvest trails foster both open habitat species and old-growth species while retention strips harbored forest interior specialists. The combination of closed canopy, stratified forest in the retention strips and gap-like conditions on the harvest trails thus increases overall species richness and maintains more diverse assemblages at the stand level than would otherwise be seen in less heterogeneous stand types. This suggests that uneven-aged silviculture may provide added conservation benefits for both open habitat and old-growth specialists than silvicultural approaches that reduce stand heterogeneity.
Copyright © 2017 Elsevier Ltd. All rights reserved.
Lisa Venier, Dave M. Morris, Jan Klimaszewski, William B Bowden, Timothy Work, Martin M. Kwiaton, Kara Webster, Paul Hazlett. Ground-dwelling arthropod response to fire and clearcutting in jack pine: Implications for ecosystem management. 2017. Can. J. For. Res. 47(12):1614-1631
DOI : 10.1139/cjfr-2017-0145
Nous avons étudié l’impact des feux de forêt et de la récolte sur la composition en espèces de trois taxons dominants d’arthropodes qui vivent dans la litière (carabes, araignées et staphylins). Cette étude a été réalisée en 2013 dans le centre-nord de l’Ontario (47°42?N, 83°36?O), dans des peuplements dominés par le pin gris (Pinus banksiana Lamb.), au moyen du piégeage dans des trappes. À l’aide de 222 espèces (12?015 individus), nous avons comparé les effets de la perturbation en utilisant des sites récemment brûlés (3 ans après un feu) et des sites coupés à blanc (3 ans après la récolte; bois en longueur, arbre entier, enlèvement des souches et coupe à la cisaille), ainsi que des peuplements plus vieux à couvert fermé qui se sont régénérés après une coupe à blanc (51 ans après la récolte) ou un feu (92 ans après le feu) en utilisant des arbres de régression multivariée. Les taxons étaient plus semblables dans les trois témoins (incluant le feu récent) que entre les témoins et les traitements impliquant une coupe, ce qui s’explique vraisemblablement par la perturbation accrue de la couverture morte dans les parcelles récoltées. De plus, les taxons étaient différents dans les parcelles plus vieilles (92 ans) issues de feux comparativement aux plus jeunes (51 ans) issues d’une coupe, ce qui indique que les communautés n’avaient pas encore récupéré à la suite de la perturbation due à la récolte, probablement à cause du manque de débris ligneux grossiers dans le peuplement plus jeune. Ces résultats indiquent que les pratiques d’aménagement forestier qui correspondent à une perturbation naturelle de la couverture morte pourraient améliorer les effets à court terme tandis que le maintien de plus de débris ligneux grossiers pourrait réduire la période de récupération des communautés épigées. [Traduit par la Rédaction]
Joakim Hjältén, Héloïse Gibb, Klara Joelsson, Therese Löfroth, Jean-Michel Roberge, Timothy Work. Biodiversity benefits for saproxylic beetles with uneven-aged silviculture. 2017. For. Ecol. Manage. 402:37-50
DOI : 10.1016/j.foreco.2017.06.064
Large scale use of even-aged silviculture (clear-cutting) commencing in the mid-20th century has had negative impacts on forest biodiversity. As a consequence, uneven-aged silviculture is currently being considered to help meet the ecological and social criteria required for sustainable forest management. Uneven-aged silviculture (e.g. selective felling) involves selective removal of some older trees in a stand which may to some extent mimics natural small scale stand dynamics and thus potentially benefit species associated with old forests. Here we test whether selective felling benefits beetle biodiversity by producing beetle assemblages that better resemble those of old growth stands than those found in uncut production stands. We conducted a field study in northern Sweden, comparing beetles assemblages collected with window traps in three spruce dominated stand types: (1) Stands recently (on average 7 years prior to the study) subjected to selective felling (Selective felling), (2) mature uneven-aged stands without recent history of management, resembling selective felling stands prior to management (Uncut), and (3) old-growth stands with high conservation values (Old growth). As predicted, we found that assemblage composition was similar in selective felling and old growth stands, and that assemblages of cambivores and obligate saproxylics (marginally significant) differed between these two stand types and uncut stands. The differences were largely explained by a higher abundance of saproxylic species presumably associated with old growth conditions and large volumes of deadwood. Thus, although overall assemblage composition did not differ between stand types, part of the beetle community seemingly benefited from selective felling. We therefore recommend that selective felling is considered as an alternative to clear-felling to maintain biodiversity values.
David Hoekman, Katherine LeVan, George E. Ball, Robert A. Browne, Robert L. Davidson, Terry L. Erwin, C. Barry Knisley, James R. Labonte, Jonathan Lundgren, David R. Maddison, Wendy Moore, Jari Niemelä, Karen A. Ober, David L. Pearson, J.R. Spence, Kipling Will, Timothy Work. Design for ground beetle abundance and diversity sampling within the National Ecological Observatory Network. 2017. Ecosphere 8(4), art. no. 01744
DOI : 10.1002/ecs2.1744
The National Ecological Observatory Network (NEON) will monitor ground beetle populations across a network of broadly distributed sites because beetles are prevalent in food webs, are sensitive to abiotic factors, and have an established role as indicator species of habitat and climatic shifts. We describe the design of ground beetle population sampling in the context of NEON's long-term, continentalscale monitoring program, emphasizing the sampling design, priorities, and collection methods. Freely available NEON ground beetle data and associated field and laboratory samples will increase scientific understanding of how biological communities are responding to land-use and climate change. © 2017 Hoekman et al.
Klara Joelsson, Joakim Hjältén, Héloïse Gibb, Jean-Michel Roberge, Therese Löfroth, Timothy Work. Uneven-aged silviculture can reduce negative effects of forest management on beetles. 2017. For. Ecol. Manage. 391:436-445
DOI : 10.1016/j.foreco.2017.02.006
Decline in biodiversity have increased the interest in alternative forest management approaches. Uneven-aged silviculture has been proposed as a mean to maintain continuity of forest canopy cover, mimic small-scale disturbances and provide a stratified forest structure similar to that of old-growth forests and therefore better maintain species associated with unmanaged forest. We used a large-scale chronosequence study spanning 50 years to study beetle diversity in uneven-aged silviculture compared with both short-term impacts and the longer-term legacy of even-aged silviculture. We compared: (1) even-aged recently clear-felled stand, (2) even-aged recently thinned stand, (3) uneven-aged stands subjected to selective felling with (4) uneven-aged reference stands to evaluate whether abundance, species richness and composition of beetles (Coleoptera) were affected differently by even-aged than by uneven-aged management. We collected 15,147 beetles from 461 species using flight interception traps in 30 stands. Beetle composition was maintained in uneven-aged managed stands; composition did not differ from unmanaged reference stands, the exception being cambium consumers. Both even-aged silviculture treatments (clear-felling and thinning) had different beetle composition compared to the reference stands, indicating that assemblages had yet to recover even 50 years into the rotation. However, beetle composition did not differ between uneven-aged managed and thinned stands. The result supports our prediction that uneven-aged silviculture better maintains beetles assemblages associated with semi-natural mature forest than even-aged silviculture. The greater temporal continuity in selectively felled stands could benefit species dependent of mature or old growth forest since some of the needed habitat qualities are continuously available. Uneven-aged silviculture could therefore serve as an important tool for landscape planning to benefit biodiversity and thus help fulfil environmental commitments. However, uneven-aged silviculture may still alter the forest and should therefore be viewed as an alternative to even-aged silviculture, rather than to set-asides. © 2017 Elsevier B.V.
Jon Andersson, Thomas Rainius, Joakim Hjältén, Timothy Work. Defining stump harvesting retention targets required to maintain saproxylic beetle biodiversity. 2016. For. Ecol. Manage. 371:90-102
DOI : 10.1016/j.foreco.2016.02.019
Stumps comprise up to 80% of the residual deadwood following clear cutting and are a significant source of biomass for bioenergetic applications. However, stump harvesting may pose significant conservation risks for saproxylic organisms that occur in residual deadwood. To define retention targets for stump harvesting operations, we compared abundance and species richness of saproxylic beetles within individual stumps as well as species accumulation curves in replicated pairs of clear cuts with and without stump harvesting in northern Sweden. Using 20 stands, we sampled 1049 stumps using eclector traps and collected 9821 beetles representing 253 species with known saproxylic biology. Nineteen of these species were red-listed in Sweden. We hypothesized that individual stumps left following stump harvesting would contain higher densities and species richness than in clear cuts without stump removal due to crowding of beetles into increasingly limited habitats. However, we found no difference in density or richness within individual stumps between control clear cuts and stumped stands. We also compared species richness between control and stumped treatments using rarefaction within individual stands and across all stands and found no difference. As with density and richness, beetle composition at the stand-level did not differ between control and stumped stands. Thus, the density of surrounding stumps within a stand had very little effect on beetle assemblages in residual stumps. We estimated the effect of stump harvest on species richness at the stand level by combining all samples and extrapolating a rarefaction curve derived from the landscape-level species pool to an accumulated sample volume of 48 m3 which corresponds to the total volume of stumps on average-sized clear cuts in Northern Sweden. Using this curve, we compared differences in species richness in average-sized clear cuts with 100% (48 m3) and 25% (12 m3) stump retention and found that stump harvest resulted in a 26% (95% C.I. 7–41%) loss of species. While the absolute scaling of the landscape-derived rarefaction does not reflect species loss at the stand-level because the combined curve reflects all rare species in the landscape, the relative species loss derived from this curve may serve as credible benchmark for species loss at the stand level following current stump harvesting practices. This benchmark may be further calibrated with additional information on number of singleton species and estimates of maximum species richness.
Brian Sturtevant, Barry J. Cook, Deepa Pureswaran, David MacLean, Daniel Kneeshaw, Louis De Grandpré, Timothy Work. Insect disturbances in forest ecosystems. 2015. Routledge Handbook of Forest Ecology pp. 93-113.
Jenna Jacobs, Yves Bergeron, Timothy Work, David Paré. Paludification of boreal soils
reduces wood decomposition rates and
increases wood-based carbon storage. 2015. Ecosphere 6(12):1-20
DOI : 10.1890/ES14-00063.1
Over long time periods, paludification reduces aboveground productivity resulting in forest retrogression. Paludified forests are typified by intense accumulation of the soil organic layer and a reduction in soil temperatures and nutrient availability. En route to paludification, early successional forests experience large inputs of deadwood biomass during the senescence of the post-fire cohort, much of which may be entombed in this rapidly growing soil organic layer. Here we examined the effects of paludification across a .2000-year chronosequence of black spruce forests on wood decomposition using three complementary approaches.We (1) repeatedly measuredwood density of logs through time, (2) utilize a time-series of logs that varied in time since death, and (3) estimate woody biomass at the stand level as it progresses from live trees to snags, logs and ultimately to buried or decomposed deadwood. Together these approaches demonstrated a 6– 7-year delay before the onset of rapid decomposition.We also found strong evidence that paludification results in a large proportion of logs becoming buried in the soil organic layer. Stand level modeling indicates that the rates of accumulation of buried deadwoodwere greatest following the senescence of the post-fire cohort when both soil organic layer build-up and creation of deadwood peaked. Following this period of high deadwood creation, stands enter a retrogressive state whereby productivity continues to decline albeit more slowly. Continued losses inwoody carbon biomass fromtrees during this retrogressive state are offset by lower wood decomposition rates and a high biomass of accumulated buried deadwood, essentially stabilizing the wood based carbon budget in these ecosystems.We recommend that partial cutting be conducted prior to or near the senescence of the post-fire cohort to improve emulation of natural forest succession in terms of both live tree and deadwood biomass. Furthermore, deadwood during this period has an extremely short residence time and the dynamics of deadwood should recover much quicker than if harvesting is conducted later in succession when there is less live tree biomass and deadwood has longer residence times.
Enrique Doblas-Miranda, Timothy Work. Localized effects of coarse woody material on soil oribatid communities diminish over 700 years of stand development in black-spruce-feathermoss forests. 2015. Forests 6(4):914-928
DOI : 10.3390/f6040914
In the black-spruce clay-belt region of Western Québec, soil nutrients are limited due to paludification. Under paludified conditions, nutrient subsidies from decomposing surface coarse woody material (CWM) may be important particularly during the later stages of ecosystem development when deadwood from senescent trees has accumulated. For soil organisms, CWM can alter microclimatic conditions and resource availability. We compared abundance and species richness of oribatid mites below or adjacent to CWM across a chronosequence which spans ca. 700 years of stand development. We hypothesized that oribatid abundance and richness would be greater under the logs, particularly in later stages of forest development when logs may act as localized sources of carbon and nutrients in the paludified substrate. However, oribatid density was lower directly under CWM than adjacent to CWM but these differences were attenuated with time. We suggest that oribatids may be affected by soil compaction and also that such microarthropods are most likely feeding on recently fallen leaf litter, which may be rendered inaccessible by the presence of overlying CWM. This may also explain the progressive decline in oribatid density and diversity with time, which are presumably caused by decreases in litter availability due to self-thinning and Sphagnum growth. This is also supported by changes of different oribatid trophic groups, as litter feeders maintain different numbers relative to CWM with time while more generalist fungi feeders only show differences related to position in the beginning of the succession. © 2015 by the authors; licensee MDPI, Basel, Switzerland.
Martin Payette, Pascal Drouin, Timothy Work, Ahmed Koubaa. Efficacy of microwave irradiation for phytosanitation of wood packing materials. 2015. Industrial Crops and Products 69:187-196
DOI : 10.1016/j.indcrop.2015.01.030
Wood packing materials (WPM) are important vectors of invasive xylophagous insects and pathogenic and decomposer wood fungi. The International Plant Protection Convention introduced the International Standards for Phytosanitary Measures No. 15 (ISPM No. 15) to regulate the development of treatments to sanitize WPM and prevent the introduction and movement of forest pests. Dielectric heating (e.g., microwave irradiation) has recently been included as an accepted treatment. In this study, the efficacy of microwave irradiation was tested on Monochamus scutellatus larvae and on four different pathogenic fungi, Gremmeniella abietina, Heterobasidion annosum, Chondrostereum purpureum, and Mycosphaerella populorum, five species of economic significance in Québec, in both jack pine and trembling aspen. We explored different temperature/time combinations on each species in order to accumulate data on the treatment. We irradiated M. scutellatus larvae at 56, 61, and 66. °C for 1-3. min and the four fungal species at 50, 55, 60, 65, 70, 75, and 90. °C for 0.5, 1, or 2. min. Fungi were tested at a wider range of temperatures to account for possible higher variation of resistance between species. We obtained 100% mortality in larvae treated at 56. °C for 2. min and at 61. °C for 1. min. The fungi species were much more resistant to the treatment. G. abietina was eliminated at 75. °C/0.5. min, H. annosum at 90. °C/1. min, M. populorum at 90. °C/2. min, and C. purpureum was still present at the highest temperature/time combination used. We demonstrated the capacity of microwave irradiation to kill the larvae with similar parameters as IPPC guidelines (60. °C for 1. min), though lethal temperatures for the fungi were very high. As the current ISPM No. 15 standard for microwave irradiation was insufficient to kill all tested fungal species, more work should be done on determining optimal combinations for the greatest number of species. Future studies should test a wider range of treatment times and expand trials to include more insect and fungal species to determine which temperature/time combination will allow us to keep both values as low as possible while assuring complete prevention of adult insect emergence and fungal re-growth.
Enrique Doblas-Miranda, Alain Paquette, Timothy Work. Intercropping trees' effect on soil oribatid diversity in agro-ecosystems. 2014. Agroforestry Systems 88(4):671-678
DOI : 10.1007/s10457-014-9680-y
The benefits of tree-based intercropping (TBI) compared to conventional agro-ecosystems in North America could include climate change mitigation and adaptation, although enhancing resilience to climate change through increasing soil diversity remains poorly explored. Diversity of soil microarthropods supports a series of ecological services that may be altered by soil desiccation due to climate change. Here we study the effect of red oak and hybrid poplar TBI on soil oribatid mite species assemblages associated to forage crops (mix of Timothy-grass and red clover). Abundance and species density of oribatids were affected by treatment, depth and the interaction of both variables. Abundance of oribatid mites was significantly lower in the oak TBI, showing a homogeneous vertical distribution in opposition to a decreasing with depth distribution under poplar TBI and conventional crops. Species density was significantly higher in the conventional crop, showing again significant differences in depth that were not present in both TBI treatments. Distance to tree did not affect mite abundance nor species density. TBI increased oribatid richness (obtained by sample-based rarefaction and extrapolation) only in the presence of oaks. The distribution of oribatids was strongly associated to tree fine root biomass and stress the importance of underground organic resources for the oribatid fauna and their ecological functions. If increasing drought associated with climate change desiccates superficial levels of agro-ecosystem soils, deeper sources of organic resources, such as tree roots, should become crucial in the maintenance of diverse microarthropod communities.
Charles Nock, Olivier Taugourdeau, Christian Messier, Daniel Kneeshaw, Timothy Work. Urban forests on the front line. 2014. Science 343(6168):249
DOI : 10.1126/science.343.6168.249-a
In their Review “The consequence of tree pests and diseases for ecosystem services” (15 November 2013, p. 823), I. L. Boyd et al. discuss the effects of pests on forest ecosystem services. However, urban forests garnered little attention.
With increasing global trade, urban trees are among the first affected by newly introduced pests. Low tree diversity combined with low tree density in cities limits the potential for compensatory responses of ecosystems, unlike the model presented by Boyd et al. Decades ago, diseased elms were felled en masse in cities in eastern North America; many of the same cities are bracing yet again for extensive canopy loss, this time due to emerald ash borer (1). Boyd et al. suggest that cultural services are affected, but a more complete portfolio includes services important to city dwellers, such as air pollution removal and climate regulation (2, 3).
As Boyd et al. suggest, planting more species and species selection will reduce losses to new tree pests. However, few species tolerate urban conditions, leading to overuse of those that do. Greater genetic diversity within species is particularly important to address enhanced pest risks in urban areas (4). Chemical treatments of urban trees can prolong their service life while also controlling pest spread (1). Outbreak-related tree removals cost millions. A greater investment in better infrastructure and soil [e.g., (5)] would be a cost-effective way to reduce stress and permit more species to be planted.
Timothy Work, Suzanne Brais, Brian Harvey. Reductions in downed deadwood from biomass harvesting alter composition of spiders and ground beetle assemblages in jack-pine forests of Western Quebec. 2014. For. Ecol. Manage. 321:19-28
DOI : 10.1016/j.foreco.2013.06.021
Renewed interest in biomass harvesting has underscored the need for ecologically relevant thresholds and empirical validation of species responses for deadwood retention if biodiversity is to be preserved in managed landscapes. We experimentally reduced volumes of downed deadwood in clear cut jack-pine stands in Western Quebec, Canada and then monitored changes in spider and ground beetle assemblages 1 and 2-years following biomass removal as well as in uncut stands. We reduced volume of downed deadwood by (1) removing residual deadwood placed on machine corridors during the initial harvest of the stand to minimize soil compaction and (2) removing all residual deadwood material throughout the experimental plots. Ground beetle and spider assemblages from deadwood depleted plots were then compared with those in clearcut plots where no additional biomass had been removed and with uncut stands to assess the incremental effect of overstory removal and subsequent biomass removal using multivariate regression trees. We identified 13,822 individual arthropods representing 177 species. We observed differences in species assemblages attributable to the effects of overstory removal (35% of the explained variance) as well as biomass removal, particularly between plots with intensive removal of biomass and those with no additional or moderate removal of biomass (11% of the explained variance). As expected we observed a range of individual species response patterns. Of particular concern were species that experienced incrementally negative effects of overstory and biomass removal and those that were strongly promoted by biomass removal. These species showed responses atypical of those observed following clear cutting and may fall outside both the range of natural variability observed in this region as well as the range of current forest management intensity practiced in North America.
Marie-Josée Morency, Jan Klimaszewski, Philippe Labrie, Armand Séguin, David Langor, Caroline Bourdon, Timothy Work, Évelyne Thiffault, Alfred F. Newton, David Paré, Margaret K. Thayer. Molecular and microscopic analysis of the gut contents of abundant rove beetle species (Coleoptera, staphylinidae) in the boreal balsam fir forest of Quebec, Canada. 2013. Zookeys 353:1-24
DOI : 10.3897/zookeys.353.5991
Experimental research on beetle responses to removal of logging residues following clearcut harvesting in the boreal balsam fir forest of Quebec revealed several abundant rove beetle (Staphylinidae) species potentially important for long-term monitoring. To understand the trophic affiliations of these species in forest ecosystems, it was necessary to analyze their gut contents. We used microscopic and molecular (DNA) methods to identify the gut contents of the following rove beetles: Atheta capsularis Klimaszewski, Atheta klagesi Bernhauer, Oxypoda grandipennis (Casey), Bryophacis smetanai Campbell, Ischnosoma longicorne (Mäklin), Mycetoporus montanus Luze, Tachinus frigidus Erichson, Tachinus fumipennis (Say), Tachinus quebecensis Robert, and Pseudopsis subulata Herman. We found no apparent arthropod fragments within the guts; however, a number of fungi were identified by DNA sequences, including filamentous fungi and budding yeasts [Ascomycota: Candida derodonti Suh & Blackwell (accession number FJ623605), Candida mesenterica (Geiger) Diddens & Lodder (accession number FM178362), Candida railenensis Ramirez and Gonzáles (accession number JX455763), Candida sophie-reginae Ramirez & González (accession number HQ652073), Candida sp. (accession number AY498864), Pichia delftensis Beech (accession number AY923246), Pichia membranifaciens Hansen (accession number JQ26345), Pichia misumaiensis Y. Sasaki and Tak. Yoshida ex Kurtzman 2000 (accession number U73581), Pichia sp. (accession number AM261630), Cladosporium sp. (accession number KF367501), Acremoniumpsammosporum W. Gams (accession number GU566287), Alternaria sp. (accession number GU584946), Aspergillus versicolor Bubak (accession number AJ937750), and Aspergillusamstelodami (L. Mangin) Thom and Church (accession number HQ728257)]. In addition, two species of bacteria [Bradyrhizobium japonicum (Kirchner) Jordan (accession number BA000040) and Serratia marcescens Bizio accession number CP003942] were found in the guts. These results not only provide evidence of the consumer-resource relations of these beetles but also clarify the relationship between rove beetles, woody debris and fungi. Predominance of yeast-feeding by abundant rove beetles suggests that it may play an important role in their dietary requirements.
Luana Graham-Sauvé, Christian Messier, Daniel Kneeshaw, Timothy Work. Shelterwood and multicohort management have similar initial effects on ground beetle assemblages in boreal forests. 2013. For. Ecol. Manage. 306:266-274
DOI : 10.1016/j.foreco.2013.06.019
Partial cutting has been proposed as a means to better conserve biodiversity in managed forest landscapes. However, partial cutting encompasses many forms of silviculture; some with implicit goals of maintaining biodiversity such as multicohort harvesting or others which may specifically focus on regeneration of stands but may still provide some additional benefits for biodiversity such as shelterwood harvesting. Here we compared ground beetle assemblages of clear cuts, shelterwoods, multicohort harvested stands and uncut stands collected using pitfall traps both 2 and 3-years post-harvest. We hypothesized that partial cutting treatments would maintain assemblages that were more similar to uncut stands than to clear cuts. We further hypothesized that among partial cuts the multicohort harvested stands, with relatively high levels of retention (66%), would maintain beetle assemblages that were more similar to uncut stands than would shelterwoods, which had lower levels of retention (50%). We collected 6692 individuals, representing 42 species. Catch rates of beetles were similar among all harvested treatments (shelterwood, multicohort and clear cuts) and lower than uncut stands. Species richness and composition was similar between shelterwood and multicohort stands. Both partial cut treatments fell between clear cuts and uncut stands in terms of species richness and compositional similarity. Compositional differences between uncut stands and partial cut stands were defined primarily by reduced abundances of forest associated species such as Agonum retractum (LeConte), Synuchus impunctatus (Say) and four Pterostichus species within partial cuts. Within partial cuts, beetle assemblages differed between machine corridors with 0% retention and adjacent partial cut strips (50% retention) and uncut vegetation corridors (100%). We conclude that both shelterwoods and multicohort harvesting stands provide at least initially similar benefits for biodiversity compared to clear cutting although neither maintains assemblages consistent with those found in uncut stands. We expect that these similarities will end once trees are removed from shelterwoods. The reductions in abundances within partial cuts may extend the time necessary for individual populations to increase to pre-harvest levels in partial cuts. For land-managers, similar initial responses of beetle assemblages in multicohort and shelterwood harvests may permit some flexibility for conservation planning whereby final removal of seed trees within shelterwoods could be delayed depending on the status of recovering beetle populations.
Jan Klimaszewski, Caroline Bourdon, Yves Bousquet, David Paré, Lisa Venier, Évelyne Thiffault, Brian D. Titus, Timothy Work. Initial responses of rove and ground beetles (Coleoptera, Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec, Canada. 2013. Zookeys 258:31-52
DOI : 10.3897/zookeys.258.4174
Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus(Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.
Émilie Robert, Kit O'Connor, Manuella Strukelj-Humphery, Danielle Celentano, Arun Bose, Brian Harvey, Suzanne Brais, Timothy Work. Ecosystem Responses to Partial Harvesting in Eastern Boreal Mixedwood Stands. 2013. Forests 4(2):364-385
DOI : 10.3390/f4020364
Partial harvesting has been proposed as a key aspect to implementing ecosystem management in the Canadian boreal forest. We report on a replicated experiment located in boreal mixedwoods of Northwestern Quebec. In the winter of 2000–2001, two partial harvesting treatments, one using a dispersed pattern, and a second, which created a (400 m2) gap pattern, were applied to a 90-year-old aspen-dominated mixed stand. The design also included a clear cut and a control. Over the course of the following eight years, live tree, coarse woody debris, regeneration and ground beetles were inventoried at variable intervals. Our results indicate that all harvesting treatments created conditions favorable to balsam fir (Abies balsamea) sapling growth and trembling aspen (Populus tremuloides) sapling recruitment. However, balsam fir and trembling aspen regeneration and ground beetles response to gap cuts were closer to patterns observed in clear cuts than in dispersed harvesting. The underlying reasons for these differing patterns can be linked to factors associated with the contrasting light regimes created by the two partial harvesting treatments. The study confirms that partially harvesting is an ecologically sound approach in boreal mixedwoods and could contribute to maintaining the distribution of stand ages at the landscape level.
Jenna Jacobs, Yves Bergeron, Hervé Bescond, Pierre Drapeau, Louis Imbeau, Nicole J. Fenton, Timothy Work. Lessons learned from 12 years of ecological research on partial cuts in black spruce forests of north-western Québec. 2013. For. Chron. 89(3):350-359
DOI : 10.5558/tfc2013-065
L’aménagement multi-cohortes qui crée ou maintient une structure irrégulière dans les peuplements forestiers a été largement préconisé pour atténuer l’impact de l’exploitation forestière. Un réseau expérimental a été mis en place dans les forêts d’épinettes noires du nord-ouest du Québec pour tester cette affirmation. Dans cet article, nous retenons deux enseignements des résultats obtenus sur la biodiversité: (1) il a fallu laisser au moins de 40 % à 60 % de la surface terrière avant coupe pour maintenir des conditions d’avant la récolte pour la plupart des groupes d’espèces, (2) les coupes partielles ont montré qu’elles avaient la capacité de produire et de maintenir de façon efficace le recrutement” du bois mort. En plus de ces deux principales conclusions, nous soulignons que les recherches à venir devraient tenter de déterminer si la récolte partielle a le potentiel de faire progresser la succession forestière.
Simon Paradis, Timothy Work. Effet des coupes partielles sur les communautés de carabes en pessière noire de l'Abitibi. 2013. Chaire industrielle CRSNG UQAT-UQAM-AFD. Note de recherche 19. 4 p.
L’aménagement de la forêt boréale modifie le paysage. La récolte rajeunit les forêts et détruit les vieilles forêts, ce qui constitueune menace pour la biodiversité inféodée aux vieux peuplements.Les coupes partielles représen-tent une solution possible qui aurait l’avantage d’allier un approvisionnement ligneux et la conservation. Par la récolte de tiges sélectionnées, elles sont en mesure de maintenir une composition et une structure similaires à celles des vieilles forêts. Cette étude avait pour objectif de vérifier l’efficacité des coupes partielles à créer un ha-bitat adéquat pour les espèces d’insectes qui dépendent des vieilles forêts de l’Abitibi. Pour ce faire, des cher-cheurs ont étudié un groupe d’insectes particulièrement sensible aux altérations de leur habitat: les carabes. Les communautés de carabes ont été échantillonnées et décrites dans des forêts naturelles d’âges différents, dans des coupes partielles impliquant divers taux de rétention et dans les coupes totales. Les résultats ont montré que la composition des communautés de carabes est davantage associée aux conditions du sol qu’à celles du cou-vert forestier. Ainsi, que la coupe soit partielle ou totale, si elle préserve l’épaisse couche de mousses au sol ty-pique des vieilles forêts de l’Abitibi, les communautés de carabes s’en trouveront peu affectées. Les résultats de cette recherche suggèrent que dans une démarche d’aménagement forestier durable et écosystémique, une at-tention particulière doit être portée à l’effet des traitements sylvicoles sur la matière organique qui couvre les sols forestiers.
Jenna Jacobs, Timothy Work. Linking deadwood-associated beetles and fungi with wood decomposition rates in managed black spruce forests. 2012. Can. J. For. Res. 42(8):1477-1490
DOI : 10.1139/X2012-075
Les champignons saprophytes et les insectes associés au bois mort sont les principaux agents de la décomposition du bois dans la forêt boréale. Les traitements sylvicoles qui modifient le microclimat et la disponibilité du bois mort pourraient avoir un impact sur la composition et le taux de croissance des communautés d’insectes et de champignons. Dans cet article, nous mettons en relation les assemblages d’insectes saproxyliques et de polypores dominants avec le taux de décomposition de la matière ligneuse et les variables environnementales dans des coupes expérimentales, partielles ou totales, et des témoins non coupés à l’aide d’une série de modèles causals, dans le but de déterminer la relation qui existe entre la structure du peuplement, la biodiversité et la fonction de l’écosystème dans les forêts d’épicéa noir (Picea mariana (Mill.) BSP). Dans l’ensemble, la composition des insectes et des champignons était différente selon que les peuplements avaient été coupés ou non. Les principaux effets de la récolte incluaient de fortes augmentations des insectes qui se nourrissent du bois et du champignon Gloeophyllum sepiarium (Wul.:Fr.) Karst. Nous croyons que ces espèces étaient favorisées par des modifications spécifiques dans les conditions de microhabitat du bois mort. En particulier dans les coupes totales, les changements dans la composition en espèces et significativement plus de degrés-jours fongiques se traduisaient par des taux de décomposition significativement plus élevés. Nous concluons que les niveaux de coupe partielle dans la gamme de 15%–20% de rétention n’étaient pas suffisants pour maintenir les communautés présentes avant la perturbation, mais qu’ils étaient suffisants pour maintenir des taux de décomposition du bois semblables à ceux des peuplements non coupés.
David Gervais, David M. Green, Timothy Work. Woodpecker excavations suitability for and occupancy by cavity users in the boreal mixedwood forest of eastern Canada. 2012. Ecoscience 19(4):391-397
Annie Hibbert, Timothy Work. Estimating species loss of saproxylic insects under scenarios of reduced coarse woody material in eastern boreal forests. 2011. Ecosphere 2(4):art41
DOI : 10.1890/ES10-00075.1
Increased exploitation of forests and residual biomass remaining after harvest has the potential to reduce biodiversity particularly of saproxylic organisms. We compare incidence-based species accumulation curves based on saproxylic flies collected using in situ emergence cages in 2006 and 2007 under two biomass harvesting scenarios. In these scenarios volume-based biomass targets would be achieved by either 1) selective removal of the largest individual pieces of coarse woody material (CWM) or alternatively 2) selective removal of smaller pieces of CWM with preferential retention of larger pieces of CWM with presumably greater conservation value. We then extrapolated a species accumulation curve to estimate thresholds of potential species loss as a function of CWM volume left within a forest stand using binomial mixing. More species would be maintained under the scenario that selectively targets larger individual pieces of CWM because of extremely large species turnover between individual sample logs and little relation between species richness and diameter of CWM. Given these circumstances, the number of individual pieces of CWM present in a stand may be more important in determining species richness than total volume of CWM for flies. When the species accumulation curve was extrapolated to stand-level volumes, species richness began to decline when CWM volumes were reduced below 40 m3/ha. We suggest that intensive management strategies aimed at recovering additional woody biomass should not exploit CWM volumes below these thresholds without mitigative measures aimed at replenishing dead wood volumes such as standing retention if maintaining biodiversity is an objective.
Read More: http://www.esajournals.org/doi/abs/10.1890/ES10-00075.1
Jenna Jacobs, Benoît St-Onge, Timothy Work. Response of female beetles to LIDAR derived topographic variables in Eastern boreal mixedwood forests (Coleoptera, Carabidae). 2011. Zookeys 147:623-639
DOI : 10.3897/zookeys.147.2013
Biodiversity monitoring is increasingly being bolstered with high resolution data derived from remote sensing such as LIDAR (Light Detection and Ranging). We derived a series of topographical variables, including slope, azimuth, ground curvature and flow accumulation from LIDAR images and compared these to captures of female carabids in pitfall traps in Eastern boreal mixedwood forests. We developed a series of species-specific logistic models predicting the proportion of females for eight dominant species, including Agonum retractum, Calathus ingratus, Platynus decentis, Pterostichus adstrictus, Pterostichus coracinus, Pterostichus pensylvanicus, Sphaeroderus nitidicollis and Synuchus impunctatus. We used these models to test three hypotheses related to how the modest topography in boreal forests could influence the availability of microhabitats and possibly potential sites for oviposition and larval development. In general, topographic features such as north facing slopes and high flow accumulation were important predictors of the proportion of females. Models derived from larger scale topography, such as hillsides or small watersheds on the order of ¼-1 ha were better predictors of the proportion of females than were models derived from finer scale topography such as hummocks and small depressions. We conclude that topography likely influences the distribution of carabids based on hydrological mechanisms rather than factors related to temperature. We further suggest based on the scale of responses that these hydrological mechanisms may be linked to the attenuation of past disturbances by wildfire and the propensity of unburned forest patches and fire skips.
A.M. Liebhold, D.G. McCullough, J.F. Cavey, Timothy Work. Airline Baggage as a Pathway for Alien Insect Species Invading the United States. 2006. American Entomologist 53(1):48-54.
D.G. McCullough, J.F. Cavey, A.M. Liebhold, D. Marshall, Timothy Work. Interceptions of nonindigenous plant pests at US ports of entry and border crossings over a 17-year period. 2006. Biological Invasions 8(4):611-630.
Despite the substantial impacts of nonindigenous plant pests and weeds, relatively little is known about the pathways by which these organisms arrive in the U.S. One source of such information is the Port Information Network (PIN) database, maintained by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service (APHIS) since 1984. The PIN database is comprised of records of pests intercepted by APHIS personnel during inspections of travelers' baggage, cargo, conveyances and related items arriving at U.S. ports of entry and border crossings. Each record typically includes the taxonomic identify of the pest, its country of origin, and information related to the commodity and interception site. We summarized more than 725,000 pest interceptions recorded in PIN from 1984 to 2000 to examine origins, interception sites and modes of transport for nonindigenous insects, mites, mollusks, nematodes, plant pathogens and weeds. Roughly 62% of intercepted pests were associated with baggage, 30% were associated with cargo and 7% were associated with plant propagative material. Pest interceptions occurred most commonly at airports (73%), U.S.-Mexico land border crossings (13%) and marine ports (9%). Insects dominated the database, comprising 73 to 84% of the records annually, with the orders Homoptera, Lepidoptera and Diptera collectively accounting for over 75% of the insect records. Plant pathogens, weeds and mollusks accounted for 13, 7 and 1.5% of all pest records, respectively, while mites and nematodes comprised less than 1% of the records. Pests were intercepted from at least 259 different locations. Common origins included Mexico, Central and South American countries, the Caribbean and Asia. Within specific commodity pathways, richness of the pest taxa generally increased linearly with the number of interceptions. Application of PIN data for statistically robust predictions is limited by nonrandom sampling protocols, but the data provide a valuable historical record of the array of nonindigenous organisms transported to the U.S. through international trade and travel. © Springer 2006.
Jan Klimaszewski, Gaetan Pelletier, C. Germain, Christian Hébert, Timothy Work. Review of Oxypoda species in Canada and Alaska (Coleoptera, Staphylinidae, Aleocharinae): Systematics, bionomics, and distribution. 2006. Canadian Entomologist 138(6):737-852.
A review of the rove beetle species of the genus Oxypoda Mannerheim from Canada and Alaska is presented. Thirty-seven species are treated, of which 4 have uncertain status, 6 are described as new to science, 8 (excluding new species) represent new distribution records for Canada, 17 (excluding new species) represent new province or territory records, 7 represent new state records, and 15 are newly synonymized. New species are Oxypoda canadensis Klimaszewski, sp. nov., O. chantali Klimaszewski, sp. nov., O. longicarinata Klimaszewski, sp. nov., O. smithi Klimaszewski, sp. nov., O. vockerothi Klimaszewski, sp. nov., and O. volkeri Klimaszewski, sp. nov. New country records are O. brachyptera (Stephens), O. gatosensis Bernhauer, O. gnara Casey, O. inimica Casey, O. orbicollis Casey, O. opaca (Gravenhorst), O. operta Sjo?berg, and O. perexilis Casey. New synonyms are O. amica Casey (= O. chillcotti Lohse syn. nov.), O. convergens Casey (= O. iowensis Casey syn. nov., O. profecta Casey syn. nov.), O. dubia Fenyes (= O. tenera Bernhauer syn. nov.), O. lucidula Casey (= O. parafunebris Lohse syn. nov.), O. manitobae Casey (= O. lata Lohse syn. nov.), O. mimetica Casey (= O. truncatella Casey, O. virginica Casey, O. canora Casey, O. latebricola Casey syn. nov.), O. perexilis Casey (= O. affecta Casey, O. croceola Casey, O. mollicula Casey, O. tenuicola Casey syn. nov.), and O. subpolaris Casey (= O. hemingi Lohse syn. nov.). The Canadian and Alaskan Oxypoda species are classified into 14 new species groups reflecting their presumed relationships. All treated species are illustrated, and distribution maps are included. New data on bionomics, distribution, and relationships are presented. Hylota ochracea Casey is removed from Oxypoda and reinstated to its original combination. © 2006 Entomological Society of Canada.
Jan Klimaszewski, D.W. Langer, Gaetan Pelletier, H.E.J. Hammond, C. Germain, Timothy Work. The effects of patch harvesting and site preparation on ground beetles (Coleoptera, Carabidae) in yellow birch dominated forests of southeastern Quebec. 2005. Can. J. For. Res. 35(11):2616-2628.
We studied the impacts of increasing size and number of gapcuts and the effects of site preparation by scarification on the species richness and community composition of ground beetles (Coleoptera: Carabidae), using pitfall traps in early-successional yellow birch dominated forests in eastern Canada. Catches of all carabids, forest specialists, and generalists were generally higher in uncut controls than in treatments. The catch of open-habitat specialists was generally lower in controls than in treatments. Although not significant, there was a common trend for scarification to decrease the catches of forest specialists and generalists. Bray-Curtis similarity measures and nonmetric multidimensional scaling ordination indicated that the composition of the carabid assemblage was more affected by harvesting treatment than by scarification. Carabid species composition varied consistently with increasing gap size and corresponded to the a priori generalized habitat-preference designations. Forest-specialist species were confined to uncut sites, while generalist species were widely distributed across all sites. Open-habitat species were found predominantly in clear-cut and two-gap sites. Hygrophilous species were consistently associated with two-gap, four-gap, and clear-cut sites. Small-gap harvesting is more favorable to the maintenance of the structure of natural arthropod assemblages than are traditional, larger clearcuts. © 2005 NRC.
Timothy Work, D.G. McCullough, J.F. Cavey, R. Komsa. Arrival rate of nonindigenous insect species into the United States through foreign trade. 2005. Biological Invasions 7(2):323-332.
Timothy Work, D.P. Shorthouse, J.R. Spence, W.J.A. Volney, David Langor. Stand composition and structure of the boreal mixedwood and epigaeic arthropods of the Ecosystem Management Emulating Natural Disturbance (EMEND) landbase in northwestern Alberta. 2004. Can. J. For. Res. 34(2):417-430.
Conservation of biological diversity under the natural disturbance model of boreal forest management relies on the assumption that natural mosaics of stand composition and structure can be adequately recreated through forest management activities. Maintaining compositional and structural features that provide adequate habitat for species within managed stands is the basis of coarse-filter conservation strategies. Here we test the effect of stand composition and stand structure on the epigaeic arthropod fauna from four boreal mixedwood cover types in western Canada. We observed differences in epigaeic community composition and species-specific associations among each of the four cover types. Differences in the carabid fauna between cover types were defined by relative abundance of carabid species associated specifically with moss cover, forb cover, and of coarse woody material, rather than unique, stand-specific species compositions of the overstory. Cover-type differences were less apparent among the comparatively species-rich spider assemblages largely because of their low abundance in undisturbed stands. For the effective conservation of all species, our results suggest that coarse-filter management of mixedwood boreal forests must incorporate structural features beyond overstory canopy composition. Our analyses also suggest that activities directed at managing the amount of coarse woody material on the ground and understory plant composition, perhaps through variable retention harvesting, is a logical first step. © 2004 NRC.
D. Marshall, J.F. Cavey, Timothy Work. Invasion pathways of Karnal bunt of wheat into the United States. 2003. Plant Disease 87(8):999-1003.
Karnal bunt of wheat (caused by Tilletia indica) was first detected in the United States in Arizona in 1996. The seed lots of infected, spring-habit, durum wheat associated with the initial detection were traced to planted fields in California, Arizona, New Mexico, and Texas. However, in the summer of 1997, the disease appeared in unrelated, winter-habit, bread wheat located over 700 km from the nearest potentially contaminated wheat from 1996 (and destroyed prior to reinfection). Here, we examined potential invasion pathways of the fungus associated with the movement of wheat into the United States. We analyzed the USDA/APHIS Port Information Network (PIN) database from 1984 through 2000 to determine likely pathways of introduction based on where, when, and how the disease was intercepted coming into the United States. All interceptions were made on wheat transported from Mexico, with the majority (98.8%) being intercepted at land border crossings. Karnal bunt was not intercepted from any other country over the 17-year period analyzed. Most interceptions were on wheat found in automobiles, trucks, and railway cars. The majority of interceptions were made at Laredo, Brownsville, Eagle Pass, and El Paso, TX, and Nogales, AZ. Karnal bunt was intercepted in all 17 years; however, interceptions peaked in 1986 and 1987. Averaged over all years, more interceptions (19.2%) were made in the month of May than in any other month. Our results indicate that Karnal bunt has probably arrived in the United States on many occasions, at least since 1984. Because of the relatively unaggressive nature of the disease and its reliance on rather exacting weather conditions for infection, we surmised that it is possible this disease has a long period of latent survival between initial arrival and becoming a thriving, established disease.
K.J. Larsen, Timothy Work. Differences in ground beetles (Coleoptera: Carabidae) of original and reconstructed tallgrass prairies in northeastern Iowa, USA, and impact of 3-year spring burn cycles. 2003. Journal of Insect Conservation 7(3):153-166.
Ground beetle assemblages were monitored at four tallgrass prairie sites burned on 3-year cycles in northeastern Iowa. The objectives of this study were to quantify differences in carabid communities between original and reconstructed tallgrass prairies, and to determine the responses of ground beetles to 3-year cycles of early spring fire commonly used to manage tallgrass prairies. Using pitfall traps, ground beetle assemblages in two original and two reconstructed tallgrass prairies were compared between 1994 and 1998, where beetles were sampled annually (0-, 1-, and 2-year post-fire conditions) from plots burned every 3 years. When burned, the greatest abundance, activity density, and species richness of carabid beetles occurred the year immediately following a spring burn, with abundance declining steadily with increased time since burning. Overall ground beetle diversity as determined by Shannon's diversity index was greatest in original tallgrass prairies several years after a fire. Some species of ground beetles were found only in original prairies, while others were found primarily in reconstructed prairie. Similarly, some species were more abundant the year immediately following a burn, while others were found in greater abundance with increased time since fire. NMS ordination and indicator species analysis clearly show differences in carabid species between original and reconstructed tallgrass prairies, but did not show differences among burn treatments.
K.J. Larsen, F.F. Purrington, Timothy Work. Habitat use patterns by ground beetles (Coleoptera: Carabidae) of northeastern Iowa. 2003. Pedobiologia 47(3):288-299.
Ground beetle assemblages were monitored in six different habitats (tallgrass prairie, oats, corn, soybean, old-field, woods) at four sites in northeastern Iowa from 1994 to 1998. The objective of this study was to quantify the influence of habitat type on the activity and distribution of ground beetles. Over five years, 13,654 ground beetles representing 107 different species were captured. Of these, 14 species represented 85% of the captured beetles. Based on habitat use, we categorized 24 as generalist species, 14 as agricultural species, 12 as grassland species, 39 as prairie specialists, and 19 as woodland species. Tallgrass prairie hosted a significantly more (P < 0.05) diverse assemblage of ground beetles than was found in the other habitats. Prairie also had a higher percentage of habitat specialists in its assemblage than did the less stable agricultural habitats which were dominated by generalists. NMS ordination and indicator species analysis revealed distinct ground beetle assemblages and identified indicator species in the various habitats, allowing species assemblages to be used as habitat indicators.
J.R. Spence, W.J.A. Volney, L.E. Morgantini, J.L. Innes, Timothy Work. Integrating biodiversity and forestry practices in western Canada. 2003. For. Chron. 79(5):906-916.
In western Canada, some forestry companies are attempting to incorporate conservation of biodiversity as a new management priority. Here we provide a review of management strategies currently implemented through a survey of companies in this region. Representatives from fourteen companies were asked to complete 30 questions designed to assess six broad issues, all of which are important for integrating biodiversity protection with timber production. Differences in provincial legislation were a major factor contributing to the prioritization of biodiversity objectives. All companies stressed that a variety of stand age classes and compositions was important for maintaining biodiversity. Green tree retention was a common approach proposed by all companies. Definitions of green tree retention varied significantly among companies, ranging from residual material left following standard clearcutting to merchantable trees selected specifically to foster wildlife and biodiversity. Most companies have proposed some monitoring aimed at biodiversity, although most plans target habitat structural features rather than directly monitoring species. © 2003 NRC.
C.M. Buddle, L.M. Korinus, Timothy Work, J.R. Spence. Pitfall trap size and capture of three taxa of litter-dwelling arthropods: Implications for biodiversity studies. 2002. Environmental Entomology 31(3):438-448.
Cost-effective and ecologically sensitive monitoring techniques are required to assess effects of anthropogenic disturbances on biodiversity. Pitfall trapping is widely used in biodiversity monitoring programs to measure the diversity of organisms active within leaf-litter. We compared catch rates and species richness of ground beetles (Coleoptera: Carabidae), rove beetles (Coleoptera: Staphylinidae), and spiders (Araneae) across five different diameters of pitfall traps (4.5, 6.5, 11, 15, and 20 cm) and three sizes of rain covers (64, 79.2, and 225 cm²) to determine optimal trap size for studying litter-dwelling arthropod biodiversity. In general, larger pitfall traps collected more individuals, and more species, of all three taxa. Further tests on data standardized to trap circumference showed that catch rates are not directly proportional to trap size, and even the smallest traps collected a disproportionately high number of certain taxa. When catch rate data were standardized by trap circumference smaller traps collected more small-bodied carabid and staphylinid species and large traps collected more wolf spiders (Lycosidae) than smaller traps. Roof size had no effect on species richness or catch rate of beetles or spiders. For the purposes of ecological monitoring, using more small pitfall traps would be the most efficient sampling technique to characterize the dominant epigaeic arthropod fauna; small traps collect few nontarget vertebrates, and sorting the samples involves generally less processing time. From a conservation perspective, however, including several large pitfall traps in the sampling regime would help detect rare species.
D.G. McCullough, Timothy Work. Lepidopteran community response to gypsy moth outbreaks is robust to guild reclassification: A reply to Summerville and Crist [2]. 2002. Environmental Entomology 31(4):584-587.
voir les plus récentes
Raphaël Grellety, Maxence Martin, Timothy Work, Gabriel Pigeon. Effet de la complexité structurelle vingt ans après des coupes totales et partielles sur les assemblages d'araignées terrestres et arboricoles en forêt boréale mixte 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
Lauren Egli, Timothy Work. Forest harvest causes rapid changes of maternal investment strategies in ground beetles 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28) youtube
Nicolas Boucher, Timothy Work, Christian Hébert. Conservation des guêpes parasitoïdes dans la forêt vierge du Ya’nienhonhndeh, une nouvelle aire protégée dans le sud du Québec 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28) youtube
Sabina Noor, Timothy Work. Les infrastructures boréales sont associées à différentes communautés de coléoptères xylophages indigènes, mais ne servent pas de voie d'introduction pour les espèces exotiques. 25e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2023-11-28)
Sabina Noor, Allison Pamela Yataco, Urszula Deregowski, Emma Despland, Timothy Work, Miguel Montoro Girona. Ravageurs forestiers en Abitibi sous changements globaux 16e colloque annuel du CEF, Université de Montréal (2023-05-08)
Lauren Egli, Timothy Work. Can rapid evolutionary adaptation to clear-cut habitats occur in ground beetles? 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Sabina Noor, Timothy Work. Comment les scieries, les mines et les terrains de camping influencent l’établissement des ravageurs non-indigènes 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Marion Noualhaguet, Nicole J. Fenton, Maxence Soubeyrand, Timothy Work. Sylviculture et aménagement forestier écosystémique, 20 ans d’observation en forêt boréale mixte 23e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue (2021-12-07)
Urszula Deregowski, Timothy Work, Miguel Montoro Girona. Effets à long terme de la coupe partielle de haute et de faible intensité sur les communautés de coléoptères saproxyliques dans la forêt boréale mixte de l'est 23e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue (2021-12-07)
Lauren Egli, Marion Noualhaguet, Nicole J. Fenton, Benoit Lafleur, Timothy Work. Évaluation à moyen terme des impacts des coupes totales et partielles sur la productivité forestière et la biodiversité en forêt boréale mixte Les Rendez-vous de la connaissance en aménagement forestier durable MFFP - Aménagement et récolte en forêt boréale (2021-06-01)
Lauren Egli, Marion Noualhaguet, Nicole J. Fenton, Benoit Lafleur, Timothy Work, Osvaldo Valeria, Igor Drobyshev, Daniela Robles, Yves Bergeron, Alexander Kryshen, Daniela Mazo Calle. Rendez-vous de la connaissance en aménagement forestier durable - Aménagement et récolte en forêt boréale Rendez-vous de la connaissance en aménagement forestier durable (2021-06-01)
Marion Noualhaguet, Nicole J. Fenton, Benoit Lafleur, Timothy Work. Sylviculture et aménagement forestier écosystémique, il s’en passe des choses en 20 ans 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Urszula Deregowski, Timothy Work, Benoit Lafleur. Les effets à long terme de l’aménagement inspiré par des perturbations naturelles sur les coléoptères saproxyliques 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Marilou Bélair, Samuel Gladu, Timothy Work. Impact des coupes forestières sur la communauté des Silphidae 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Samuel Gladu, Timothy Work. Impacts à long terme des coupes partielles successives sur la composition des coléoptères forestiers 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Lauren Egli, Timothy Work, Benoit Lafleur. Évaluation du rétablissement et de la persistance des carabes sur 20 ans après la gestion des écosystèmes forestiers dans les forêts boréales mixtes 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Nicolas Boucher, Marilou Bélair, Timothy Work. L’évaluation de la biodiversité des insectes dans le Ya’nienhonhndeh – un des derniers massifs forestiers dans le sud du Québec 22e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, complètement virtuel (2020-12-02)
Samuel Gladu, Timothy Work. Impacts à long terme des coupes partielles successives sur la composition des coléoptères forestiers 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Lauren Egli, Timothy Work, Benoit Lafleur. Récupération des carabes suivant des pratiques sylvicoles conventionnelles et écosystémiques dans l'ouest du Québec 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Samuel Gladu, Timothy Work. Affiche 5
Impact long terme de l’aménagement forestier
équien et inéquien sur la composition des carabes. 20e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Lorrainville, Québec. (2018-11-30)
