David W. Langor

Potential for range expansion of mountain pine beetle into the boreal forest of North America.

Abstract The potential for mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), to expand its historical range in North America from west of the continental divide into the eastern boreal forest was assessed on the basis of analyses of the effects of climate and weather on brood development and survival, and key aspects of the interaction of mountain pine beetle with its hosts and associated organisms. Variation in climate suitability and high host susceptibility in the boreal forest create a finite risk of establishment and local persistence of low-level mountain pine beetle populations outside their historical range. Eventually, these populations could become widespread and cause epidemic infestations, creating an ecological pathway eastward through the boreal forest. Such infestations would reduce the commercial value of forests and impose an additional disturbance on native ecological systems.

Fire residuals as habitat reserves for epigaeic beetles (Coleoptera: Carabidae and Staphylinidae)

We studied litter-dwelling beetles (Coleoptera: Carabidae and Staphylinidae) in residual patches of unburned forests (fire residuals) left by two natural wildfires in high-elevation coniferous forests in western Alberta, Canada. Fire residuals were wet, latesuccessional patches of fir and spruce stands, and served as refugia for populations of forest-dwelling beetle species. The largest fire residuals contained older living trees than the mature forest surrounding the burnt areas. Pterostichus empetricola, a glacial relict beetle species, was associated only with habitats provided by the fire residuals. Although there was no relationship between the size of fire residuals and beetle diversity or activity-abundance, more Nebria crassicornis were collected per trap in larger residuals, suggesting dependence of this species on late-seral attributes present within the largest residuals. Conservation of habitats equivalent to fire residuals in managed forests will likely contribute to landscape continuity and preservation of faunal elements common in wildfire-origin landscapes. # 2001 Elsevier Science Ltd. All rights reserved.

Influence of boreal forest succession and dead wood qualities on saproxylic beetles

1 Saproxylic insects, a functional group dominated by beetles, are dependent on dead or moribund trees as habitat elements.

Diversity of non-native terrestrial arthropods on woody plants in Canada

A list of non-native phytophagous insects and mites on woody plants (trees, shrubs, vines) in Canada was compiled using information from literature and input from taxonomists. The 419 recorded species include Hemiptera (53% of species), Lepidoptera (22%), Coleoptera (13%) and Hymenoptera (9%). Almost all species originate from the Palearctic, especially Europe, reflecting historical trade patterns. About 41% of species were directly introduced to Canada from countries of origin, and the remainder spread from the United States of America (USA) after initial establishment there. Major ports on the east and west coasts, on Lake Erie and Lake Ontario are the main points of entry for exotic species directly introduced, and southern British Columbia (BC), Ontario (ON) and Quebec (QC) are the major points of entry for species spreading from the USA. Consequently, BC, ON, QC and Nova Scotia have the highest diversity of non-native species, and the prairie provinces and northern territories have the lowest. The extent of the distribution of individual species is related to length of time in Canada, number of introductions and dispersal abilities. Almost all native woody plant genera in Canada have been invaded by exotic phytophages. The large majority of phytophages occur on angiosperms. Woody plant genera with the largest distribution, highest species diversity and highest local abundances tend to host the greatest number of non-native species, including Picea, Pinus, Malus, Prunus, Salix, Betula, Quercus, Pyrus and Populus. The arrival rate of species in Canada increased from the late nineteenth century until about 1960, and declined rapidly thereafter. Quarantine legislation enacted in the USA in 1912 and in Canada in 1976 seems to have reduced the rate of insect invasion.

Saproxylic insect assemblages in Canadian forests: diversity, ecology and conservation

Saproxylic insect assemblages inhabiting dead wood in Canadian forests are highly diverse and variable but quite poorly understood. Adequate assessment of these assemblages poses significant challenges with respect to sampling, taxonomy, and analysis. Their assessment is nonetheless critical to attaining the broad goals of sustainable forest management because such species are disproportionately threatened elsewhere by the reductions in dead wood generally associated with commercial exploitation of northern forests. The composition of the saproxylic fauna is influenced by many factors, including tree species, degree of decay, stand age, and cause of tree death. Wildfire and forest harvesting have differential impacts on saproxylic insect assemblages and on their recovery in postdisturbance stands. Exploration of saproxylic insect responses to variable retention harvesting and experimental burns is contributing to the development of prescriptions for conserving saproxylic insects in boreal forests. Understanding of processes that determine diversity patterns and responses of saproxylic insects would benefit from increased attention to natural history. Such work should aim to provide a habitat-classification system for dead wood to better identify habitats (and associated species) at risk as a result of forest management. This tool could also be used to improve strategies to better maintain saproxylic organisms and their central nutrient-cycling functions in managed forests.

Wood-feeding beetles and soil nutrient cycling in burned forests: implications of post-fire salvage logging.

1 Rising economic demands for boreal forest resources along with current and predicted increases in wildfire activity have increased salvage logging of burned forests. Currently, the ecological consequences of post‐fire salvage logging are insufficiently understood to develop effective management guidelines or to adequately inform policy decision‐makers. 2 We used both field and laboratory studies to examine the effects of post‐fire salvage logging on populations of the white‐spotted sawyer Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae) and its ecological function in boreal forest. 3 Monochamus s. scutellatus adults were relatively abundant in both burned and clear‐cut logged sites but were absent from salvage logged sites. 4 An in situ mesocosm experiment showed that the abundance of M. s. scutellatus larvae in burned white spruce bolts was linked to changes in total organic nitrogen and carbon in mineral soil. 5 Organic nutrient inputs in the form of M. s. scutellatus frass increased mineral soil microbial respiration rates by more than three‐fold and altered the availability of nitrogen. Changes in nitrogen availability corresponded with decreased germination and growth of Epilobium angustifolium and Populus spp. but not Calamagrostis canadensis. 6 Although the present study focused on local scale effects, the reported findings suggest that continued economic emphasis on post‐fire salvage logging may have implications beyond the local scale for biodiversity conservation, nutrient cycling and plant community composition in forest ecosystems recovering from wildfire.

Effects of Postfire Salvage Logging on Deadwood-Associated Beetles

In Canada and the United States pressure to recoup financial costs of wildfire by harvesting burned timber is increasing, despite insufficient understanding of the ecological consequences of postfire salvage logging. We compared the species richness and composition of deadwood-associated beetle assemblages among undisturbed, recently burned, logged, and salvage-logged, boreal, mixed-wood stands. Species richness was lowest in salvage-logged stands, largely due to a negative effect of harvesting on the occurrence of wood- and bark-boring species. In comparison with undisturbed stands, the combination of wildfire and logging in salvage-logged stands had a greater effect on species composition than either disturbance alone. Strong differences in species composition among stand treatments were linked to differences in quantity and quality (e.g., decay stage) of coarse woody debris. We found that the effects of wildfire and logging on deadwood-associated beetles were synergistic, such that the effects of postfire salvage logging could not be predicted reliably on the basis of data on either disturbance alone. Thus, increases in salvage logging of burned forests may have serious negative consequences for deadwood-associated beetles and their ecological functions in early postfire successional forests.

Evaluation of carabid beetles as indicators of forest change in Canada 1

Our objective was to assess the potential of carabid beetles (Coleoptera: Carabidae) as effective bioindicators of the effects of forest management at a Canadian national scale. We present a comparison of carabid beetle assemblages reported from large-scale studies across Canada. Based on the initial response following disturbance treatment, we found that carabid assemblages consistently responded to disturbance, but responses of individual species and changes in species composition were nested within the context of regional geography and finer scale differences among forest ecosystems. We also explored the relationship between rare and dominant taxa and species characteristics as they relate to dispersal capacity and use of within-stand habitat features such as coarse woody debris. We found no relationship between life-history characteristics (such as body size, wing morphology, or reported associations with downed wood) and the relative abundance or frequency of occurrence of species. Our results suggest that carabids are better suited to finer scale evaluations of the effects of forest management than to regional or national monitoring programs. We also discuss several knowledge gaps that currently limit the full potential of using carabids as bioindicators.

Variable retention harvest of white spruce stands and saproxylic beetle assemblages

Dead wood dependent (saproxylic) insects have been identified as vulnerable to the effects of modern forestry practices. We examined the effects of variable retention harvesting on saproxylic beetle assemblages. Variable retention of living green trees seeks to leave more forest structure on the landscape with the goal of maintaining ecosystem function and biodiversity. Ninety flight-intercept traps were divided between recently dead natural snags and snags killed by gir- dling in three replicated forest stands with 10%, 20%, 50%, and 75% residual structure and in uncut control stands. Beetles were collected and identified during the second and third summers post harvest and grouped for analyses as (i) wood- and bark-borers, (ii) fungivores, and (iii) predators. Harvesting intensity explained a relatively small amount of the variability in the beetle assemblages. However, all groups responded strongly to coarse woody debris variables and especially to snag decay class during the third postharvest summer, suggesting that factors associated with coarse woody debris quality and quantity determine the initial responses and successional trajectories of saproxylic beetle assemblages. The main effects of variable retention on saproxylic assemblages are expected to be mediated through differences in amount of coarse woody debris expected to materialize with the death and decay of green trees left as residual elements.

Records of adventive aleocharine beetles (Coleoptera: Staphylinidae: Aleocharinae) found in Canada

Eight additional adventive aleocharine beetles, native to the Palaearctic region, are reported from Canada, five of them for the first time. They belong to three tribes: Crataraea suturalis (Mannerheim) (Nova Scotia, Saskatchewan, British Columbia) and “Meotica pallens (Redtenbacher)” (Ontario, British Columbia) belong to Oxypodini; Atheta (Chaetida) longicornis (Gravenhorst) (Nova Scotia, Quebec), Atheta (Thinobaena) vestita (Gravenhorst) (New Brunswick), Dalotia coriaria (Kraatz) (Alberta), Dinaraea angustula (Gyllenhal) (Nova Scotia, Prince Edward Island, Quebec, Alberta), and Nehemitropia lividipennis (Mannerheim) (New Brunswick, Nova Scotia, Prince Edward Island, Quebec, Ontario) belong to Athetini; and Homalota plana (Gyllenhal) (Nova Scotia, New Brunswick) belongs to Homalotini. These species have likely been introduced into Canada from Europe by various anthropogenic activities, and their bionomics and possible modes of introduction are discussed. For each species, a short diagnosis and habitus and genital images are provided to assist with identification. The habitus and genital images are presented here for the first time for these species in North America. New United States records are not included in the abstract.