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Efficient post-drought recovery of growth and assimilation enables a plant to return to its undisturbed state and functioning. Unlike annual plants, trees suffer not only from the current drought, but also from cumulative impacts of consecutive water stresses which cause adverse legacy effects on survival and performance. This review provides an integrated assessment of ecological, physiological and molecular evidence on the recovery of growth and photosynthesis in trees, with a view to informing the breeding of trees with a better ability to recover from water stress. Suppression of recovery processes can result not only from stress damage but also from a controlled downshift of recovery as part of tree acclimation to water-limited conditions. In the latter case, recovery processes could potentially be activated by turning off the controlling mechanisms, but several obstacles make this unlikely. Tree phenology, and specifically photoperiodic constraints, can limit post-drought recovery of growth and photosynthesis, and targeting these constraints may represent a promising way to breed trees with an enhanced ability to recover post-drought. The mechanisms of photoperiod-dependent regulation of shoot, secondary and root growth and of assimilation processes are reviewed. Finally, the limitations and trade-offs of altering the photoperiodic regulation of growth and assimilation processes are discussed., (© 2024 Cambridge Philosophical Society.)

Small isolated plant populations are one of the consequences of fragmentation of natural habitats by humans. We asked what effect does the creation of smaller populations from larger ones has on the plant fitness-related trait seed germination. Using information on 119 species (142 species entries) in 50 families, we found that seeds in only 35.2% of the species entries from larger populations germinated to higher percentages than those from smaller populations. In the other entries, seeds from large and small populations germinated equally well (57.7% of total entries) or seeds from small populations germinated better (7.0% of total entries) than those from large populations. These results indicate that population size is not a reliable predictor of seed germinability. Furthermore, there was little relationship between seed germination and either seed mass, genetic diversity or degree of population isolation, or between population size and genetic diversity. [ABSTRACT FROM AUTHOR]

Many forest types globally have been subject to an increase in the frequency of, and area burnt by, high-severity wildfire. Here we explore the role that previous disturbance has played in increasing the extent and severity of subsequent forest fires. We summarise evidence documenting and explaining the mechanisms underpinning a pulse of flammability that may follow disturbances such as fire, logging, clearing or windthrow (a process we term disturbance-stimulated flammability). Disturbance sometimes initiates a short initial period of low flammability, but then drives an extended period of increased flammability as vegetation regrows. Our analysis initially focuses on well-documented cases in Australia, but we also discuss where these pattens may apply elsewhere, including in the Northern Hemisphere. We outline the mechanisms by which disturbance drives flammability through disrupting the ecological controls that limit it in undisturbed forests. We then develop and test a conceptual model to aid prediction of woody vegetation communities where such patterns of disturbance-stimulated flammability may occur. We discuss the interaction of ecological controls with climate change, which is driving larger and more severe fires. We also explore the current state of knowledge around the point where disturbed, fire-prone stands are sufficiently widespread in landscapes that they may promote spatial contagion of high-severity wildfire that overwhelms any reduction in fire spread offered by less-flammable stands. We discuss how land managers might deal with the major challenges that changes in landscape cover and altered fire regimes may have created. This is especially pertinent in landscapes now dominated by extensive areas of young forest regenerating after logging, regrowing following broadscale fire including prescribed burning, or regenerating following agricultural land abandonment. Where disturbance is found to stimulate flammability, then key management actions should consider the long-term benefits of: (i) limiting disturbance-based management like logging or burning that creates young forests and triggers understorey development; (ii) protecting young forests from disturbances and assisting them to transition to an older, less-flammable state; and (iii) reinforcing the fire-inhibitory properties of older, less-flammable stands through methods for rapid fire detection and suppression., (© 2023 Cambridge Philosophical Society.)

Links between proglacial lakes and glacier dynamics are poorly understood but are necessary to predict how mountain glaciers will react to a warmer, wetter climate, where such lakes are expected to increase both in number and volume. Here, we examine a long-term (~120 year) record of terminus retreat, thinning and surface velocities from in-situ and remote sensing observations at the terminus of Kaskawulsh Glacier, Yukon, Canada, and determine the impact of a local proglacial hydrological reorganisation on glacier dynamics. After an initial deceleration during the late 1990s, terminus velocities increased at a rate of 3 m a−2 from 2000–12, while proglacial Slims Lake area increased simultaneously. The rapid drainage of the lake in May 2016 substantially altered the velocity profile, decreasing annual velocities by 48% within 3 km of the terminus between 2015 and 2021, at an average rate of ~ 12.5 m a−2. A key cause of the rapid drop in glacier motion was a reduction in flotation of the lower part of the glacier terminus after lake drainage. This has important implications for glacier dynamics and provides one of the first assessments of the impacts of a rapid proglacial lake drainage event on local terminus velocities. [ABSTRACT FROM AUTHOR]

The forest tent caterpillar, Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), is an irruptive forest pest found throughout North America. Widespread species such as M. disstria are exposed to historical and contemporary processes that are not uniform and can generate regionally distinct genomic variation. Previous analyses used a short mitochondrial fragment to infer broad-scale phylogeographic patterns in M. disstria, whereas nuclear markers have been previously applied only in a smaller geographic region. In this study, we quantified M. disstria population variation with genome-wide single nucleotide polymorphisms and cytochrome c oxidase from mitochondrial DNA. Using highly variable genome-wide markers, we resolved clear genomic differences among populations of M. disstria east of the Rocky Mountains that were not detected using mitochondrial variation alone. We also did not detect host-associated divergence in either our genomic or mitochondrial data. Our results highlight the utility of genome-wide markers to resolve intraspecific population structure within a widespread species and support the need for further biogeographic sampling of this forest insect pest. [ABSTRACT FROM AUTHOR]

In an epoch of rapid environmental change, understanding and predicting how biodiversity will respond to a changing climate is an urgent challenge. Since we seldom have sufficient long-term biological data to use the past to anticipate the future, spatial climate-biotic relationships are often used as a proxy for predicting biotic responses to climate change over time. These 'space-for-time substitutions' (SFTS) have become near ubiquitous in global change biology, but with different subfields largely developing methods in isolation. We review how climate-focussed SFTS are used in four subfields of ecology and evolution, each focussed on a different type of biotic variable - population phenotypes, population genotypes, species' distributions, and ecological communities. We then examine the similarities and differences between subfields in terms of methods, limitations and opportunities. While SFTS are used for a wide range of applications, two main approaches are applied across the four subfields: spatial in situ gradient methods and transplant experiments. We find that SFTS methods share common limitations relating to (i) the causality of identified spatial climate-biotic relationships and (ii) the transferability of these relationships, i.e. whether climate-biotic relationships observed over space are equivalent to those occurring over time. Moreover, despite widespread application of SFTS in climate change research, key assumptions remain largely untested. We highlight opportunities to enhance the robustness of SFTS by addressing key assumptions and limitations, with a particular emphasis on where approaches could be shared between the four subfields., (© 2023 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.)

The lower Athabasca River basin in northeastern Alberta contains one of the highest known concentrations of prehistoric archaeological sites in the boreal forests of western Canada. This is due to the combination of readily available sources of lithic raw material stone near a major travel corridor, and extensive archaeological survey conducted in advance of oil sands mining. Typological studies have proposed immediate post-glacial occupations that were contemporaneous with, or immediately followed, the catastrophic glacial Lake Agassiz flood through the area at the end of the Pleistocene. Here, we complement the typology age estimates by using stratigraphic relations and infrared stimulated luminescence (IRSL) dating of aeolian material to determine the age of initial human occupation, and reconstruct the environment encountered by early inhabitants of the region. We find that the first occupations in our study area took place near the Pleistocene-Holocene boundary (ca. 11.3 ± 0.8 ka BP), shortly after catastrophic flooding from Lake Agassiz. The post-flood environment was dominated by cold climatic conditions that supported permafrost, presumably during the late Pleistocene, and underwent significant aeolian deposition. Our results indicate that this area represents a portion of the eastern edge of the deglacial corridor into which plants, animals, and humans dispersed following retreat of the Laurentide Ice Sheet. [ABSTRACT FROM AUTHOR]

A unique regional climate progression, ca 14.2-11.5 cal ka BP, in the eastern Great Lakes region of North America is suggested by subfossil logs, high-resolution 14C dates, and established proxy records in New York, USA. The progression began with a northern boreal-type climate ca. 14.2-13.1 ka coeval with the expansion of Lake Iroquois, a transition to a southern boreal-type climate 13.1-12.9 ka that coincided with the transition of Lake Iroquois into progressively lower lake levels, and a continuation of the southern boreal-type climate 12.9-11.5 ka. These conditions and changes are evident in the tree rings and relative dominance of tamarack (Larix laricina) and spruce species (Picea spp.) plus the presence of black ash (Fraxinus nigra) as the only thermophilous species. Together they suggest variations in atmospheric moisture levels, surface winds, temperature extremes, and/or an enhanced seasonality over time. Here we propose that the evolution of the glacial Great Lakes and their interactions with ice sheets, meltwater, winds, and regional topography created a regional glacial lake-effect climate, 14.2-11.5 cal ka BP, that was opposite to the established warming Bølling-Allerød-cold Younger Dryas climate progression. [ABSTRACT FROM AUTHOR]

Despite extensive paleoenvironmental research on the postglacial history of the Kenai Peninsula, Alaska, uncertainties remain regarding the region's deglaciation, vegetation development, and past hydroclimate. To elucidate this complex environmental history, we present new proxy datasets from Hidden and Kelly lakes, located in the eastern Kenai lowlands at the foot of the Kenai Mountains, including sedimentological properties (magnetic susceptibility, organic matter, grain size, and biogenic silica), pollen and macrofossils, diatom assemblages, and diatom oxygen isotopes. We use a simple hydrologic and isotope mass balance model to constrain interpretations of the diatom oxygen isotope data. Results reveal that glacier ice retreated from Hidden Lake's headwaters by ca. 13.1 cal ka BP, and that groundwater was an important component of Kelly Lake's hydrologic budget in the Early Holocene. As the forest developed and the climate became wetter in the Middle to Late Holocene, Kelly Lake reached or exceeded its modern level. In the last ca. 75 years, rising temperature caused rapid changes in biogenic silica content and diatom oxygen isotope values. Our findings demonstrate the utility of mass balance modeling to constrain interpretations of paleolimnologic oxygen isotope data, and that groundwater can exert a strong influence on lake water isotopes, potentially confounding interpretations of regional climate. [ABSTRACT FROM AUTHOR]

Climate changes over the past two millennia in the central part of the Gulf of St. Lawrence are documented in this paper with the aim of determining and understanding the natural climate variability and the impact of anthropogenic forcing at a regional scale. The palynological content (dinocysts, pollen, and spores) of the composite marine sediment core MSM46-03 collected in the Laurentian Channel was used to reconstruct oceanographic and climatic changes with a multidecadal temporal resolution. Sea-surface conditions, including summer salinity and temperature, sea-ice cover, and primary productivity, were reconstructed from dinocyst assemblages. Results revealed a remarkable cooling trend of about 4°C after 1230 cal yr BP (720 CE) and a culmination with a cold pulse dated to 170-40 cal yr BP (1780-1910 CE), which likely corresponds to the regional signal of the Little Ice Age. This cold interval was followed by a rapid warming of about 3°C. In the pollen assemblages, the decrease of Pinus abundance over the past 1700 yr suggests changes in wind regimes, likely resulting from increased southerly incursions of cold and dry Arctic air masses into southeastern Canada. [ABSTRACT FROM AUTHOR]

We studied responses of carabid beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine forests in the foothills of Alberta, Canada during 2013–2014 and compared the results with those from a similar study conducted in the same area during 1989–1990. Assemblages from stands regenerating 12–53 years after harvest gradually recovered towards their presumed preharvest condition represented by old pyrogenic stands. Assemblage structure in postharvest stands of similar age had also largely converged with that in stands that had burned in 1957 and 1997. Composition of ground vegetation, mineral soil cover, and basal area of trees and shrubs were significantly correlated with carabid assemblage structure, suggesting that plant successional gradients and patterns in carabid assemblages are driven by similar factors. We found that no carabid species was strictly associated with old pyrogenic stands, although assemblages in pyrogenic stands were distinctive. We predict that composition of carabid assemblages in harvested stands will recover and roughly match the variable structure of assemblages remaining in old, never-cut pyrogenic stands, given sufficient time (≥ 50 years). Nonetheless, the carabid fauna of the eastern slopes of Alberta's Rocky Mountains appears to be changing in response to factors other than forestry. Warming climate is an explanation consistent with the changes observed. [ABSTRACT FROM AUTHOR]

Dung beetles (Coleoptera: Scarabaeidae (Aphodiinae, Scarabaeinae) and some Geotrupidae) provide important ecosystem services on pastures by disrupting and burying deposits of cattle dung. The extent of these services is influenced by the number of individuals and species present, which may differ with habitat type. In the present study, we compared dung beetle assemblages in a mosaic of open grassland and wooded habitats on native fescue pastures in the Cypress Hills of southern Alberta, Canada. Using pitfall traps baited with cattle dung and operated from spring through autumn for two years at each of the two sites, we collected 4944 individuals representing 14 dung beetle species. More individuals and species were recovered in grassland habitat, which was dominated by nonnative species associated with cattle dung. Wooded habitat was dominated by a native species associated with deer dung. Dwellers (species that develop within the dung deposit) comprised 93% of the beetles recovered during the study. Significant variation in annual beetle counts in the two habitats highlights the value of studies conducted over multiple years. These results emphasise the importance of habitat diversity and interspecific habitat preference in structuring dung beetle assemblages on fescue grasslands, which are among the most threatened ecosystems in Canada. [ABSTRACT FROM AUTHOR]

We describe an experimental protocol for measuring the response of spruce budworm postdiapause larval development to temperature. This protocol is specifically designed to include measurements of development near their upper and lower thermal thresholds. The application of this protocol to a laboratory colony allowed for the first experimental evidence that spruce budworm larval development occurs at temperatures as low as 5 °C and as high as 35 °C, and it provides data to fit stage-specific development models. Our protocol is also designed to minimise mortality near the thermal development thresholds, thus allowing for multigenerational studies. We observed developmental plasticity in larvae reared at constant temperatures, particularly the occurrence of up to 42% of some individuals requiring only five instars to complete development compared to the expected six instars. The occurrence exhibited no clear relation to temperature. Although this protocol is specifically designed for spruce budworm, it provides a template for the study of other species' developmental responses to temperature. [ABSTRACT FROM AUTHOR]

Fatty acid (FA) levels and profiles are vital for soybean oil quality, while cytokinins (CKs) and abscisic acid (ABA) are potent regulators of plant growth and development. Previous research suggested associations between FA biosynthesis and hormonal signalling networks; however, hormonal regulation of FA accumulation during soybean (Glycine max) seed maturation has never been measured. We analysed hormone and FA profiles obtained from HPLC-(ESI)-MS/MS and GC-FID screening during soybean seed maturation. A multilayered data processing approach, involving heat-maps, principal component analysis (PCA), correlation and multiregression models, suggested a strong relationship between hormone metabolism and FA/oil accumulation during seed maturation. Most strikingly, positive correlations were found between the levels of CK ribosides [transZeatin riboside (tZR), N6-isopentenyladenosine (iPR)] at the early stages of SM (R5-R6) and C18:0, C18:2 and oil content at the R8 stage. Moreover, multiple regression models revealed functional linkages between several CK derivatives and FA and oil content in mature seeds. To further test the significance of hormone regulation in FA metabolism, plants of two soybean accessions with contrasting hormone and FA profiles were sprayed with exogenous ABA and transZeatin (tZ) during the seed-filling period (R5-R6). Depending on the hormone type and concentration, these treatments distinctly modified biosynthesis of all tested FAs, except for C18:0. Most remarkably, tZ (50 nM) promoted production of C16:0, C18:1, C18:2, C18:3, and oil accumulation in maturing seeds. Overall, the results indicate impactful roles for ABA and CKs in FA accumulation during SM and represent a further step towards understanding FA biosynthesis, and potential improvements of soybean oil profiles. [ABSTRACT FROM AUTHOR]

Summary: Approximately 80% of neotropical forests are subject to unsustainable economic practices, such as logging. Spiders are a megadiverse taxonomic group with a particularly great diversity in forest ecosystems and could help indicate the sustainability of logging operations. At six sites at 400–700 m altitude in the piedmont forest of north-western Argentina, spiders collected using pitfall traps and forest structure and spider assemblage structure variables were quantified in order to examine the association between them and to identify indicator spider families. Logging changes forest structure and seems to generate an unsuitable habitat for spiders associated with mature forests. The family taxonomic level is a good surrogate for spider morphospecies. The Mysmenidae, Nemesiidae, Theridiidae, Pholcidae, Hahniidae and Tetragnathidae families were associated with upper canopy cover of 20% or more and with more than two dead fallen trees per 0.1 ha and >15 live trees per 0.1 ha, found in unlogged forests. Bearing in mind that the piedmont forest of north-western Argentina is being logged in the absence of sustainability criteria, we suggest including spiders in monitoring schemes to complement the information obtained from more readily used groups, such as charismatic vertebrates. [ABSTRACT FROM AUTHOR]

Spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), is a destructive defoliator found throughout the Nearctic boreal forest. This pest has a broad geographic range and shows regional variation in key life history traits. These population differences may represent important adaptations to local environmental conditions and reflect underlying genetic diversity. Existing laboratory colonies of spruce budworm do not capture this regional variation, so we established five new spruce budworm colonies from across its range to explore regional adaptations among spruce budworm populations within common garden experiments. We present methods for establishing new spruce budworm laboratory colonies from wild populations. We describe the process of flushing, rearing, and disease screening used on these new populations to produce healthy disease-free laboratory stocks. [ABSTRACT FROM AUTHOR]

This interdisciplinary study presents a human perspective on climatic variations by combining documentary, discursive, instrumental, and proxy data. Historical sources were used to characterize climate variations along the coast of Labrador/Nunatsiavut during the 19th century and the first half of the 20th century. Written and early instrumental archives provided original information on the state and perception of climate before the establishment of meteorological stations, which permitted an intra-annual perspective on climatic variations. Written sources depicted the sensitivity of humans to climatic variations. Exceptional seasonal climatic events were extracted from documentary and discursive sources, which were complemented by tree-ring and early instrumental data. From 1780 to 1900, data indicated a succession of relatively warm and cold episodes. Most warm periods were described as stormy and variable. The final part of the studied records showed cold conditions from 1900 to 1925 and warm conditions from 1925 to 1950. Historical sources helped to discriminate a seasonal signal. Mild autumn-winter conditions were recorded since 1910 in relation with positive anomalies of the North Atlantic Oscillation in winter. Relatively warm spring-summer conditions were recorded after 1920, which corresponds to a phase of positive anomaly of the Atlantic Multidecadal Oscillation. [ABSTRACT FROM AUTHOR]

The back cover of the August 2016 issue of the journal "Canadian Entomologist" is presented.

Although the use of nonhost plants intercropped among host crops has been a standard agricultural practice for reducing insect herbivory for millennia, the use of nonhost signals to deter forest pests is much more recent, having been developed over the past several decades. Early exploratory studies with synthetic nonhost volatile semiochemicals led to targeted electrophysiological and trapping experiments on a variety of bark and ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) across three continents. This work disclosed a suite of antennally and behaviourally active nonhost volatiles, which are detected in common across a range of coniferophagous bark beetles. It also established the fact that dispersing bark and ambrosia beetles detect nonhost signals while in flight and avoid nonhost trees without necessarily landing on them. Later work showed that groups of synthetic nonhost volatiles, sometimes combined with insect-derived antiaggregants, are effective in protecting individual trees and forest stands. Further work in this system may lead to the development of a variety of new and useful tactics for use in various integrated pest management strategies. [ABSTRACT FROM AUTHOR]

Outside of pest control reports, little attention has been paid to interior ecosystems in high-latitude regions. Opportunistic sampling of live arthropods captured inside the University of Alaska Museum Fairbanks, Alaska, United States of America allowed us to describe and analyse one such interior ecosystem. We document a minimum of 77 arthropod species over 18 years. Beetles, spiders, and booklice represented 80% of the total abundance. Of those captured, synanthropes consisted primarily of fungivores and detritivores, seasonals consisted primarily of predators and omnivores, and transients consisted primarily of predators and had greater diet and species diversity than the synanthropes and transients. January was the most common month for capturing synanthropes, September for capturing seasonals, and July for capturing transients. Four synanthropic species not previously known from Alaska, which appear to have breeding populations inside the museum, were found: Dorypteryx domestica (Smithers, 1958) (Psocodea: Psyllipsocidae), Cartodere constricta (Gyllenhal, 1827), Dienerella filum (Aubé, 1850), and Corticaria serrata (Paykull 1800) (Coleoptera: Latridiidae). Three transient and one synanthrope species previously unreported from Alaska, with no evidence of breeding populations, were also found: the click beetle Danosoma obtectum (Say, 1839) (Coleoptera: Elateridae), a spider in the genus Phantyna, probably the species P. bicornis (Emerton, 1915) (Araneae: Dictynidae), two Colobopsis sp. ant specimens (Hymenoptera: Formicidae), and the synanthropic spider Oecobius cellariorum (Dugès, 1836) (Araneae: Oecobiidae). [ABSTRACT FROM AUTHOR]

Quantifying tree biomass is an important research and management goal across many disciplines. For species that exhibit predictable relationships between structural metrics (e.g. diameter, height, crown breadth) and total weight, allometric calculations produce accurate estimates of above-ground biomass. However, such methods may be insufficient where inter-individual variation is large relative to individual biomass and is itself of interest (for example, variation due to herbivory). In an East African savanna bushland, we analysed photographs of small (<5 m) trees from perpendicular angles and fixed distances to estimate above-ground biomass. Pixel area of trees in photos and diameter were more strongly related to measured, above-ground biomass of destructively sampled trees than biomass estimated using a published allometric relation based on diameter alone (R2 = 0.86 versus R2 = 0.68). When tested on trees in herbivore-exclusion plots versus unfenced (open) plots, our predictive equation based on photos confirmed higher above-ground biomass in the exclusion plots than in unfenced (open) plots (P < 0.001), in contrast to no significant difference based on the allometric equation (P = 0.43). As such, our new technique based on photographs offers an accurate and cost-effective complement to existing methods for tree biomass estimation at small scales with potential application across a wide variety of settings. [ABSTRACT FROM AUTHOR]

The willow sawfly, Nematus oligospilus (Förster), is a pest in Salix commercial forests and has been reported worldwide. Female adults must recognize a suitable host plant to oviposit, since her offspring lack the ability to move to another host. We evaluated the effect of conspecific herbivory on the oviposition choices of N. oligospilus females by providing damaged (DP) and undamaged (UP) plants of Salix humboldtiana, a native willow from South America, as oviposition substrates. Local and systemic effects were studied. For the local treatment, a twig from the DP with damaged leaves was contrasted to a twig from a UP in dual choice experiments. For systemic treatment, a twig from the DP with intact leaves was contrasted to a twig from a UP. We estimated the use of olfactory and contact cues by comparing volatile emission of DP and UP, and by analysing the behaviour of the females during host recognition after landing on the leaf surface. In the context of the preference–performance hypothesis (PPH), we also tested if oviposition site selection maximizes offspring fitness by evaluating neonate hatching, larval performance and survival of larvae that were born and bred on either DP or UP. Our results demonstrate that previous conspecific herbivory on S. humboldtiana has a dramatic impact on female oviposition choices and offspring performance of the sawfly N. oligospilus. Females showed a marked preference for laying eggs on UP of S. humboldtiana. This preference was found for both local and systemic treatments. Volatile emission was quantitatively changed after conspecific damage suggesting that it could be related to N. oligospilus avoidance. In the dual choice preference experiments, the analysis of the behaviour of the females once landing on the leaf surface suggested the use of contact cues triggering egg laying on leaves from UP and avoidance of leaves from DP. Furthermore, 48 h of previous conspecific feeding was sufficient to dramatically impair neonate hatching, as well as larval development and survival, suggesting a rapid and effective reaction of the induced resistance mechanisms of the tree. In agreement with the PPH, these results support the idea that decisions made by colonizing females may result in optimal outcomes for their offspring in a barely studied insect model, and also opens the opportunity for studying tree-induced defences in the unexplored South American willow S. humboldtiana. [ABSTRACT FROM AUTHOR]

Southern pine beetles (Dendroctonus frontalis Zimmermann) and symbiotic fungi are associated with mass mortality in stands of Caribbean pine (Pinus caribaea Morelet). This study provides a 12.7-year assessment of semiochemical mediation between southern pine beetle and Caribbean pine in relation to concentrations of 4-allylanisole (estragole, methyl chavicol) and monoterpenes measured by gas chromatography–mass spectrometry in different seasons in premontane and coastal pine stands of Belize and Guatemala. Individual trees and stands with >2.5% (relative mass %) of 4-allylanisole in the xylem oleoresin exhibited significantly less beetle-induced mortality than those with <2.5%. Changes in relative levels of 4-allylanisole and monoterpenes during this study are consistent with seasonal temperature and cumulative water deficit effects and suggest bark beetle attack of P. caribaea may intensify in the future. [ABSTRACT FROM AUTHOR]

Summary: Despite the global significance of the Leach's Storm-petrel Hydrobates leucorhous colony on Baccalieu Island, Newfoundland and Labrador, Canada, the estimate of 3.36 million breeding pairs reported for 1984 by Sklepkovych and Montevecchi stands as the single published population estimate for the world's largest colony. This study increases knowledge of this population by analysing data from additional independent surveys conducted in 1984 and 1985, and by updating the population status with a survey conducted in 2013. Population estimates were derived by extrapolating occupied burrow densities to the estimated occupied area of four main habitat types (heath, forest, grass and fern), which in turn were based on proportions of habitats observed in plots (1984 and 1985) or by using a Geographic Information System approach (2013). Based on these surveys, the Leach's Storm-petrel breeding population size on Baccalieu Island was estimated at 5.12 ± 0.73 (SE) and 4.60 ± 0.42 (SE) million pairs in 1984 and 1985 respectively, representing estimates 37–51% greater than the original 1984 survey. While discrepancies among these estimates were largely driven by the way occupied areas were estimated, our study confirms that Baccalieu Island hosts the largest Leach's Storm-petrel colony in the world. Results from the 2013 survey estimate the current breeding Leach's Storm-petrel population at 1.95 ± 0.14 (SE) million pairs, representing a 42% decline over 29 years (-1.4% per year), relative to the original published estimate of 3.36 ± 0.12 (SE) million pairs. The most prominent change has occurred in the density of storm-petrel burrows found in forest habitat which dropped by 70% despite forest remaining the second most abundant habitat available to nesting storm-petrels on Baccalieu Island. The cause of this decline remains unknown and is likely multi-faceted. Future research focusing on demographic studies is required to understand what is driving the population decline of this internationally important colony. [ABSTRACT FROM AUTHOR]

Multi-proxy analyses of a sequence spanning the Younger Dryas (YD) in the Glacial Lake Hind basin of Manitoba provides insight into regional paleohydrology and paleovegetation of meltwater rivers and lakes spanning >4000 yr; the sequence is controlled by 25 new accelerator mass spectrometry ages. This lake, dammed by the Laurentide Ice Sheet, overflowed into Lake Agassiz. The pre-YD interval records rapid sedimentation from meltwaters that headed in proglacial lakes in the Canadian Prairies that are known to have been catastrophically released when ice or sediment barriers were breached. Pollen in this phase is dominated by pre-Quaternary forms eroded from Paleocene bedrock. At the onset of the YD at ~12.8 cal ka, the sudden appearance of concentrations of nanodiamonds, high-temperature magnetic spherules, platinum, and iridium provide evidence of an extraterrestrial (ET) event that others have identified at more than 40 sites in North America. Major changes in oceans and climate, and the catastrophic outflow of nearby Lake Agassiz at the onset of the YD, may be related. Lower water levels and a reduction of Souris River inflow to Lake Hind followed, which are reflected by more clayey and organic-rich sediments and a decrease in pre-Quaternary palynomorphs. This may have resulted from the deepening of river valleys caused by the release of meltwater triggered by the ET event. Wetlands then began to develop, leading to peat deposition from 12.3 to 11 cal ka. This was followed by a fluvial episode depositing sand and then by increased Holocene aridity that resulted in accumulation of a thick sequence of dune sands. A dry woodland environment with a mix of conifers (especially Picea and Larix) and deciduous trees (especially Populus and Quercus) covered the uplands from ~13 to 10 cal ka. [ABSTRACT FROM AUTHOR]

Masting and regeneration dynamics were investigated in a long-term perspective using Abies cephalonica as a study tree species. Extensive fieldwork was implemented in Parnitha National Park, Greece, following a large-scale wildfire. Annual cone production was monitored for a 5-year period in 130 tagged trees, in 13 plots with 10 individuals each, established both within the unburned part of the forest and in surviving fragments of the burned area. In the most recent masting year, a high percentage (88%) of cone-bearing trees was recorded, along with a sizeable, average cone production (40.8 cones per tree). In the intermediate, non-masting years, the corresponding values ranged from 2% to 55% and 0.08 to 5.9 cones per tree, respectively. The reproduction process is affected by both tree density and regional climatic conditions, in particular temperature during spring of the maturation year and precipitation during spring and summer of the previous year. For the first time according to our knowledge, natural regeneration was recorded for a 4-year period, in 13 permanent transects within the monitoring plots, in relation with a masting event and the additional implications of a preceding wildfire. Highest mean density of seedlings and saplings (11.4 per m2) was observed during the first spring after masting. In the non-masting years, the corresponding value ranged from 2.1 to 2.9 per m2. Seedling survival during their first summer was considerable (30–76%) but stabilized afterwards (1–3 years) at a lower level (10–20%). The particular post-masting seedling flush was followed by an extremely high mortality rate (88.6%) and cannot represent a major recruitment event. [ABSTRACT FROM AUTHOR]

Tebufenozide (Mimic) kills Lepidoptera larvae that ingest it. Aerial applications of tebufenozide were made against spruce budworm (Choristoneura fumiferana (Clemens)) (Lepidoptera: Tortricidae) in boreal forest in Manitoba, Canada, in 1999 and 2000. In 2000 and 2001, moths in sprayed and unsprayed plots were sampled with light traps; trapping was supplemented by foliage sampling. Relative to unsprayed plots, catches of spruce budworm moths in plots sprayed in 1999 and 2000 were depressed in 2000, but not in 2001. Host tree defoliation was reduced in 2000 by 1999 and 2000 applications; the 2000 application reduced numbers of spruce budworm larvae in 2000 and 2001. Multivariate analysis revealed negative effects of tebufenozide application on two species of non-target moths in 2000 and no negative effects in 2001. Negatively affected species have larvae feeding in the tree canopy at the time of spray application. Higher catches of non-target species in sprayed treatments were observed for three species in 2000 and two species in 2001. We conclude that tebufenozide can depress the numbers of spruce budworm larvae and provide foliage protection during the year of application and the following year, and that negative effects on non-target species are detectable for about 15 months after application. [ABSTRACT FROM AUTHOR]

Tree-ring reconstructions of temperature often target trees at altitudinal or latitudinal tree line where annual growth is broadly expected to be limited by and respond to temperature variability. Based on this principal, regions with sparse tree line would seem to be restricted in their potential to reconstruct past temperatures. In the northeastern United States, there are only two published temperature reconstructions. Previous work in the region reconstructing moisture availability, however, has shown that using a greater diversity of species can improve reconstruction model skill. Here, we use a network of 228 tree-ring records composed of 29 species to test the hypothesis that an increase in species diversity among the pool of predictors improves reconstructions of past temperatures. Chamaecyparis thyoides alone explained 31% of the variability in observed cool-season minimum temperatures, but a multispecies model increased the explained variance to 44%. Liriodendron tulipifera , a species not previously used for temperature reconstructions, explained a similar amount of variance as Chamaecyparis thyoides (12.9% and 20.8%, respectively). Increasing the species diversity of tree proxies has the potential for improving reconstruction of paleotemperatures in regions lacking latitudinal or elevational tree lines provided that long-lived hardwood records can be located. [ABSTRACT FROM AUTHOR]

In this work we tested the suitability of thermistor strings as automatic tools for the continuous measurement of glacier ice ablation. Experimental data collected in summer 2017 over an Italian glacier provided ice ablation readings with accuracy similar to manual measurements with ablation stakes and other automatic systems, like the draw-wire method and the Bøggild ablatometer. Thermistor strings have potential for future applications in remote glacier monitoring, thanks to their flexibility, simple construction, and robustness. [ABSTRACT FROM AUTHOR]

The depth at which pitfall traps were sunk into the ground and the resulting catches of epigaeic Carabidae (Coleoptera) and Staphylinidae (Coleoptera) assemblages in subhygric to hydric ecosites with very deep organic soil layers was investigated in the upper foothills ecoregion of Alberta, Canada. Traps were installed at seven sites, with six surface traps (the pitfall trap lip <5 cm below soil surface) and six deep traps (the pitfall trap lip >20 cm below soil surface) at each site. A total of 5289 beetles representing 75 taxa were collected. There were no significant effects of trap depth on catch. Rarefaction estimates of species diversity were higher in surface pitfall traps for both taxa. The similarity of pooled catches between deep and surface traps was on average 75%, suggesting that both trap types were collecting similar faunas. We found no advantage to using deep pitfall traps in addition to surface traps to sample the epigaeic fauna of wet forest stands and peatlands. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Entomologist is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Obtaining corn hybrid seeds (Zea mays L.) with high vigour depends on the parental lines and the direction of the cross, and this relates to seed desiccation tolerance and composition. This research studied reciprocal crosses between pairs of proprietary, elite parent lines (L1 and L5; L2 and L4) producing hybrid seeds with different qualities attempting to correlate vigour with seed composition, focusing on storage proteins, starch and soluble sugar amounts. Four corn hybrid seed lots produced from reciprocal crosses were compared (HS 15 with HS 51, and HS 24 with HS 42) by assessing germination, vigour, and seedling emergence in the field. Seed composition was assessed in mature, dehydrated seeds. Proteins were extracted, quantified, and analysed by electrophoresis and densitometry. Starch amounts were assessed using a kit and soluble sugars were determined using high performance liquid chromatography with pulsed electrochemical detection. The L1 and L2 lineages, used as female parents, provided seeds with lower vigour; however, the quantification of major protein bands, and sucrose, raffinose and stachyose were similar between seed lot pairs. While both total seed protein and starch varied between reciprocal hybrids for one of the two sets of crosses, the amounts of neither correlated with seed vigour. Interestingly, hybrids with low seed vigour (HS 15, HS 24) accumulated greater amounts of fructose relative to their reciprocal; correlation analysis confirmed these results. We demonstrate different effects on seed vigour dependent on the maternal parent in reciprocal crosses producing hybrid corn seeds. We also show that vigour is negatively correlated with seed reducing sugar contents. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Entomologist is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Managing for multiple ecosystem services is a growing issue for forest managers. As trade-offs arise between conflicting management objectives, stakeholders must be informed of the possible outcomes of alternative choices in order to facilitate decision-making. We modelled stand dynamics under single-management and functional zoning multiple-management (TRIAD; i.e. three-zone) scenarios in different forest types typical of eastern North America with the Forest Vegetation Simulator (FVS). Timber production, carbon stocking and habitat quality ecosystem services were calculated with simulation outputs. Habitat quality was measured using a habitat suitability index that integrated stand structural indicators. A multi-criteria decision analysis (MCDA) was performed in order to rank scenarios. We show that the most intensive management yielded greater timber volumes but resulted in the weakest carbon and habitat quality scores. The TRIAD scenarios in sugar maple–beech stands offered the best compromise in services compared to single management. In shade-intolerant deciduous stands, there was a loss of timber production with TRIAD scenarios, but greater carbon stock and habitat quality were observed. Our study contrasts alternative management scenarios for ecosystem services in woodlots of different forest types. It confirms that multiple harvest systems better achieve multiple services. The coupling of simulation modelling with MCDA offers a simple and flexible method to help stakeholders and managers make sound decisions. [ABSTRACT FROM PUBLISHER]

Wapusk National Park is part of the Hudson Bay Lowlands in Manitoba and covers 11 475 km2. Lichen surveys were initiated in 2002 but none have reported all species incorporating broad habitat types or a baseline on which to make management decisions. The objectives of this study were: 1) to determine species diversity, including species richness and evenness of the lichens present; 2) to explore species distributions; and 3) to compare lichen growth form and substratum relationships among physiographic regions. Fifty-six locations in four habitat types (physiographic regions: open coastal beach ridge, forested coastal beach ridge, boreal transition forest, and peat plateau bog) and three burned locations were visited over nine years and specimens were collected at each location. A total of 276 species and subspecies were collected. One species is new to Canada (Buellia uberior Anzi) and ten species are new to Manitoba. Species diversity, evenness, and richness were highest in the coastal beach ridge. The open coastal beach ridge, boreal transition forest, and peat plateau bogs formed separate clusters in the non-metric multidimensional scaling (NMS) but the forested coastal beach ridge overlapped with the open coastal beach ridge. Unique species in each region may serve as indicators to monitor long-term changes. While the coastal beach ridge facilitates travel along the coast, it also represents the region with the highest need for intervention to conserve species diversity. [ABSTRACT FROM PUBLISHER]

A number of insect species in a variety of families and orders damage early regenerating forests. Successful management of pests of regenerating forests requires detailed information on the natural history of the damaging organism, including the factors that increase risk, and a careful assessment of the risk mitigation options. Decision support systems, in the form of stand models capable of incorporating pest management options are required to guide decisions in terms of the expected yields under various pest management scenarios. In this paper we review research to date on the natural history and damage of the most important insect pests of regenerating forests in Canada and propose a framework for risk assessment. Canadian scientists have been active contributors to the research that advanced this field, from the early descriptive studies, to the development of practical tools to assist industry in managing pests of young forests. [ABSTRACT FROM AUTHOR]

The balsam twig aphid, Mindarus abietinus Koch (Hemiptera: Aphididae), is one of the most important pests of balsam fir (Abies balsamea (Linnaeus) Miller; Pinaceae) grown as Christmas trees in eastern North America. Aphid feeding on the current-year shoots results in needle distortion and shoots stunting, which reduces the aesthetic value of balsam fir trees and can have substantial economic impact. Syrphidae (Diptera) fly predators attacking this aphid are poorly known. We identified four species attacking the balsam twig aphid. Syrphus torvus Osten Sacken (Diptera: Syrphidae) was the most abundant species followed by Eupeodes lapponicus (Zetterstedt) (Diptera: Syrphidae) and Eupeodes americanus (Wiedemann) (Diptera: Syrphidae). We described the seasonal natural history of the two most abundant syrphids feeding on this aphid and we studied their synchrony with their prey. Syrphid larval density on balsam fir shoots increased rapidly and closely followed density of the balsam twig aphid. We also reported heavy parasitism of syrphid pupae by two Hymenoptera on tree foliage but lower parasitism on pupae in the soil under trees. Several cases of multiple parasitism and hyperparasitism were observed in syrphid pupae under trees. Abundance of predaceous syrphid species was higher in untreated balsam fir plantations compared with treated plantations. More research is needed to understand the role and the impact of these predators on balsam twig aphid population dynamics. [ABSTRACT FROM PUBLISHER]

We evaluated the effect of tree genotype on the resistance of balsam fir, Abies balsamea (Linnaeus) Miller (Pinaceae), to damage from the balsam twig aphid, Mindarus abietinus Koch (Hemiptera: Aphididae), by visually assessing aphid damage in clonal seed orchards located in New Brunswick and Nova Scotia, Canada, during four consecutive years. Estimates of clone mean heritability were moderate, suggesting that heritability of resistance is influenced by genetic factors. In New Brunswick, positive phenotypic and genetic correlations of clone-mean damage among years indicate that clones rank similarly each year. Our results suggest that selectively breeding for increased resistance could result in genetic gains. [ABSTRACT FROM PUBLISHER]

We review the literature on effects of inbreeding depression (ID) on seed germination for 743 case studies of 233 species in 64 families. For 216 case studies, we also review the relationship between mass and germination in inbred vs. outbred seeds. Inbred seeds germinated equally well as outbred seeds in 51.1% of 743 case studies, but better than outbred seeds in only 8.1%. In c. 50.5% of 216 cases, mass of inbred seeds was equal to (38.0%) or larger than (12.5%) that of outbred seeds. The magnitude of ID spans most of the − 1 to +1 range for relative performance for germination of inbred vs. outbred seeds; in contrast to what might be expected, seed germinability often is not negatively correlated with the coefficient of inbreeding (F) or positively corrected with population genetic diversity; neither heterosis nor outbreeding depression for germination is common in crosses between populations; and ID in most endemics is low and does not differ from that of widespread congeners. Our results on the effects of ID on seed mass and germination do not agree with the limited number of comparisons Darwin (1876) made on the effects of selfing vs. outcrossing on these two life-history traits. Recommendations are made on how to improve dormancy breaking and germination procedures in order to make the results of studies on ID more relevant to the natural world. [ABSTRACT FROM PUBLISHER]

The maple leafcutter moth (Paraclemensia acerifoliella (Fitch) (Lepidoptera: Incurvariidae) has been discovered in western Canada, feeding on saskatoon (Amelanchier alnifolia (Nuttall) Nuttall ex Roemer (Rosaceae)), a previously undocumented host. New records are detailed, and historical records are reviewed and assessed. Western populations are compared morphologically, genetically, and ecologically to populations feeding on maple (Acer Linnaeus; Sapindaceae) in eastern Canada. Paraclemensia Busck species host plants are discussed in relation to the hypothesised phylogenetic history of the genus. Although maple feeding is hypothesised to be the ancestral condition in the genus Paraclemensia, Rosaceae feeding (including Amelanchier) is hypothesised to be a derived capability of the P. acerifoliella species group. [ABSTRACT FROM PUBLISHER]

Streams draining the Cypress Hills support unique and understudied macroinvertebrate communities in Saskatchewan, Canada. Here, we report the discovery of a species of caddisfly new to the Cypress Hills and Saskatchewan, Neophylax splendens Denning (Trichoptera: Thremmatidae). Larvae were collected early in May 2012, and are found to enter pre-pupal diapause in mid-June until mid-September. Larvae were identified as N. splendens by morphological characters and verified with genetic analysis. Its occurrence strengthens the biogeographical link between the montane regions in British Columbia, Canada and Utah, United States of America with the southwest corner of Saskatchewan. This study highlights the importance of seasonal sampling, resolute species level identifications in biological surveys and the use of genetic analyses to obtain this level of identification. [ABSTRACT FROM PUBLISHER]

Scaphoideus titanus is the invasive vector of the phytoplasma causing the Flavescence dorée in European vineyards. This epidemic is a serious threat to viticulture that has been increasing for more than 60 years in Europe. We studied the effect of synchrony with the plant phenology and the effect of plant-sap quality on the individual fitness. Thus, we conducted laboratory experiments to determine if insect hatchings were synchronized with grapevine bud break. We used two natural populations: one from a cold winter vineyard and one from a mild winter vineyard. In both cases, egg hatching was synchronized with bud break and leaf appearance. The phloem quality of the young and old leaves as a food source was analysed by high-performance liquid chromatography, and the effects on S. titanus growth were evaluated. Phloem composition varied with the grapevine cutting's age but also varied between leaves of different ages from the same plant. The older leaves were less nutritious because they had the highest carbon-to-nitrogen ratio and the lowest content of essential amino acids. Despite diverse phloem qualities, no fitness difference was observed. We found that the synchronization of egg hatchings with bud break is well regulated. However, the nymphs are not affected by the phloem-sap quality, suggesting that S. titanus may accept different food qualities and that egg hatching synchrony could contribute to population expansion in vineyards. [ABSTRACT FROM PUBLISHER]

We report on a 2009 survey of Acacia woodlands in the Seronera area of central Serengeti, Tanzania, and compare the results to previous surveys from the 1970s–1980s. We document a substantial change in woodland structure and composition. From 1978 to 2009, woody plant density (mean ± SD) declined from 255 ± 35 trees ha−1 to 147 ± 14 trees ha−1. Canopy cover declined from 15.1 ± 1.9% to 5.7 ± 0.6%. Canopy volume declined from 1810 ± 207 m3 ha−1 to 1410 ± 121 m3 ha−1. A 19% increase in the relative canopy volume of Acacia robusta, a species avoided by the giraffe, represents a sharp decline in the quality of the giraffe's food supply, which was last comprehensively assessed in 1978. We examine these changes in the context of Pellew's 1983 woodland dynamics model describing the impacts of elephant, giraffe and fire on an Acacia tortilis tree population and determine that our data are qualitatively consistent with this model. We hypothesize that selective elephant and giraffe browsing has contributed to an increase in the relative dominance of unpalatable species, consistent with Pellew's predictions. [ABSTRACT FROM PUBLISHER]

Outbreaks of insect pests periodically cause large losses of volume in Canada’s forests. Compounded with climate change, outbreaks create significant challenges for managing the sustainable delivery of ecosystem services. Current methods to monitor damage by these pests involve both field and aerial surveys. While relatively cost effective and timely, aerial survey consistency and spatial coverage may be insufficient for detailed monitoring across Canada’s vast forest-land base. Remote sensing can augment these methods and extend monitoring capabilities in time and space by incorporating knowledge of pest-host interactions and of how damage translates into a remote sensing signal for detection and mapping. This review provides a brief introduction to major forest insect pests in Canada (two bark beetles (Coleoptera: Curculionidae) and six defoliators) and the damage they cause, a synthesis of the literature involving aerial survey and remote sensing, and a discussion of how these two approaches could be integrated into future pest monitoring from a Canadian perspective. We offer some lessons learned, outline roles that remote sensing could serve in a management context, and discuss what ongoing and upcoming technological advances may offer to future forest health monitoring. [ABSTRACT FROM AUTHOR]

Almost 100 years have passed since J.M. Swaine, the assistant entomologist in charge of Forest Insect Investigations, wrote, “Canadian bark-beetles: a preliminary classification, with an account of the habits and means of control”. The goal was to “put into the hands of practical foresters information of inestimable practical value… to prevent the continued loss of timber now being destroyed” by “the most insidious enemies of the forest”. In this paper, we celebrate Swaine’s pioneering work by summarising the foundational aspects of his early treatise of 1918: the “general habits” of bark beetles, classifications of their behaviour, causes of population increase, and mitigation tactics. In the founding text, Swaine identified all major Dendroctonus Erichson (Coleoptera: Curculionidae) bark beetles found in Canada, although details on life histories were scarce. We summarise current knowledge of the life histories and population dynamics of the spruce beetle, D. rufipennis Kirby; the Douglas-fir beetle, D. pseudotsugae Hopkins; the eastern larch beetle, D. simplex; and address the current range expansion of mountain pine beetle, D. ponderosae Hopkins. We review how aspects of global change, such as invasive species, have altered the population dynamics of certain bark beetles. Finally, we conclude with lessons from two of the many past contributors to bark beetle ecology in Canada, J.M. Swaine and H.A. Richmond. [ABSTRACT FROM AUTHOR]

Chemical insecticides have been an important tool in the management of forest insect pests in Canadian forests. Aerial application of insecticides began in the 1920s and expanded greatly after World War II with the widespread adoption of DDT primarily for the suppression of spruce budworm, Choristoneura fumiferana Clemens (Lepidoptera: Tortricidae), and other defoliating insects. Significant progress was made in the development of new chemical insecticides and formulations including fenitrothion and tebufenozide, as well as technology for the application of insecticides against various insect pests. However, widespread opposition to the use of chemical insecticides in forest management has led to significant reductions in the number of insecticides registered for use in Canadian forests. Developments in the past 20 years have focussed on new insecticides, formulations, and technologies that seek to limit the impacts on non-target organisms and subsequent ecosystem effects. These developments have resulted in significant improvements in the management of traditional management targets, such as the spruce budworm (Choristoneura fumiferana (Clemens); Lepidoptera: Tortricidae) but also the management of invasive species, especially wood-boring beetles (Coleoptera: Buprestidae, Cerambycidae). [ABSTRACT FROM AUTHOR]

Our review highlights research during the past century focussed on the population ecology of outbreak-prone insect defoliators in Canadian forests. Based on reports from national and provincial surveys that began in the 1930s, there have been at least 106 insect defoliators reported to outbreak, most of which are native Lepidoptera, Hymenoptera (sawflies), or Coleoptera (in order of frequency from most to least). Studies comparing life-history traits of outbreak versus non-outbreak species to better understand why certain species are more outbreak-prone indicate several traits especially common among outbreak species, including egg clustering and aggregative larval feeding. There have been at least 50 time-series studies examining the spatiotemporal population behaviour of 12 major defoliator species. These studies provide evidence for both regular periodicity and spatial synchrony of outbreaks for most major species. Life-table studies seeking to understand the agents causing populations to fluctuate have been carried out for at least seven outbreak species, with the majority identifying natural enemies (usually parasitoids) as the major driver of outbreak collapse. Our review concludes with several case studies highlighting the impact and historical underpinnings of population studies for major defoliator species and a discussion of potential avenues for future research. [ABSTRACT FROM AUTHOR]

The impacts of insect outbreaks on tree mortality, productivity, and stand development in Canada are reviewed, emphasising spruce budworm (Choristoneura fumiferana (Clemens), Lepidoptera: Tortricidae) and mountain pine beetle (Dendroctonus ponderosae Hopkins, Coleoptera: Curculionidae). Reduced growth and survival are a function of insect population and defoliation level. It is feasible to make short-term (annual) predictions of insect population and defoliation based upon sampling, but long-term, multi-year predictions are problematic. Given the historical record, it is expected that outbreaks will occur with relatively predictable frequency and basic host relationships and abiotic constraints will not change dramatically. However, the precision of predictions at fine scales is variable and reduced over time. Relationships between tree growth reduction, survival, and cumulative defoliation or beetle population level are available for major insect species. Understanding insect outbreak effects hinges on mortality, changes in interspecies competition, regeneration, and succession. Altered stand dynamics caused by insects can be interpreted for indicators such as wildlife habitat, old forest, riparian buffer cover, viewscapes, and connectivity. Anthropogenic changes are altering impacts via range expansions, northward shifts, and changes in forest composition. We can better understand effects of insect outbreaks and how best to ameliorate damage through a combination of empirical permanent plot studies, modelling, and manipulative experiments. [ABSTRACT FROM AUTHOR]

Canada has a distinguished history of research in forest entomology. The number of peer-reviewed publications emanating from studies in forest entomology in Canada greatly increased following the Second World War. Much of the outstanding historical success in Canadian forest entomological research is attributable to the work of entomologists employed by the Canadian Forest Service, who authored the majority of studies until the mid 1970s and usually published them in The Canadian Entomologist. Since that time the majority of studies have been published by Canadian universities in a broad range of journals. Most early research in forest entomology in Canada was carried out by men, but since that time the proportion of forest entomological research carried out by women has increased significantly. The majority of research in central and eastern Canada focussed on defoliators and their natural enemies and host plants whereas the majority of research in western Canada examined bark beetles (Coleoptera: Curculionidae: Scolytinae) and their natural enemies and host plants. Although publications on defoliators and their natural enemies have occurred continuously throughout the historical development of forest entomology in Canada, the numbers of publications on wood borers (Coleoptera: Buprestidae, Cerambycidae) and bark beetles and their natural enemies have never been higher than they are presently. [ABSTRACT FROM AUTHOR]