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Given the substantial impacts of non-native species on invaded systems, an understanding of the rates and spatial patterns of invasive spread is critical. Spread may vary across spatial scales, with dispersal of invasive species occurring both via diffusive spread at local sites and long-distance jump dispersal at larger scales. Research on earthworm invasions in North American forests has focused on patterns of spread across landscapes, with less examination of spread at local sites. We sampled the exotic earthworm Dendrobaena octaedra (Savigny, 1826) on 500 m x 500 m grids at three sites in the boreal forest of northeastern Alberta in 2006 and again in 2012-2013 to examine distributional changes over time. Earthworms spread farther from roads (the presumed site of initial introduction) over time, and spatial patterns at our sites suggest transport by vehicles and waterways are key vectors of dispersal at the local level. Spread was estimated to be occurring at a rate of at least 17.9 m/year. Our study indicates that both diffusive spread and jump dispersal of earthworms can be important at local scales and that local diffusive spread may be substantially higher than previously estimated. Key words: boreal forest, Dendrobaena octaedra, earthworms, invasive species, local spread, spatial pattern, spread rate. Etant donne les impacts considerables des especes non indigenes sur les systemes envahis, la comprehension des taux et de la distribution spatiale de la dissemination envahissante est d'une importance critique. La dissemination peut varier selon l'echelle spatiale, la dispersion d'especes envahissantes s'effectuant tant par dissemination par diffusion a l'echelle locale que par dispersion par grands sauts a des echelles plus grandes. La recherche sur les invasions de lombrics dans les forets nordamericaines s'est axee sur les motifs de dissemination a l'echelle des paysages, s'interessant moins a la dissemination locale. Nous avons echantillonne du lombric exotique Dendrobaena octaedra (Savigny, 1826) sur des grilles de 500 m x 500 m en trois sites dans la foret boreale du nord-est de l'Alberta en 2006, puis en 2012-2013, afin d'examiner les variations de leur repartition dans le temps. La dissemination des lombrics s'eloignait des routes (sites presumes de l'introduction initiale) avec le temps, les motifs de repartition spatiale dans les sites etudies donnant a penser que les vehicules et les cours d'eau constituent des vecteurs cles de la dispersion a l'echelle locale. Il a ete estime que la dissemination s'effectuait a un taux d'au moins 17,9 m/an. Notre etude indique que tant la dissemination par diffusion que la dispersion par sauts des lombrics peuvent etre importantes a des echelles locales et que la dissemination locale par diffusion peut etre sensiblement plus importante que ce que laissaient croire les estimations passees. [Traduit par la Redaction] Mots-cles: foret boreale, Dendrobaena octaedra, lombrics, espece envahissante, dissemination locale, motif spatial, taux de dissemination., Introduction Information on the spread of non-native species is essential for predicting and managing invasions. However, determining rates of spread is challenging because data from multiple time points and across [...]

More than 1180 non-native species, mostly of Palaearctic origin, have been recorded from the boreal zone of Canada, with the highest diversity on the island of Newfoundland and in the southern boreal zone of Ontario and Quebec. The non-native biota of the boreal zone (and of Canada in general) is poorly known in terms of species composition and distribution. A large proportion of species are associated with disturbed anthropogenic habitats such as urban areas, agricultural landscapes, transportation and communication corridors, and industrial developments. Natural habitats in the boreal zone have a high degree of resistance to invasion compared with those of other Canadian zones, likely owing to harsh climates, low light levels, poor soil nutrient availability, low soil pH, low productivity, and dense covering of the ground by plants, especially bryophytes. Of the relatively few non-native species that have successfully colonized the boreal zone, many decline greatly in abundance after a few years, suggesting biotic resilience. To date the boreal zone has shown the least resistance and resilience to large vertebrates (moose and white-tailed deer) translocated to islands, diseases of vertebrates, and earthworms. In general, the ecological impacts of non-native species on the boreal zone have been poorly studied, and there are few examples where such impacts are evident. Likewise, there has been little attempt to quantify the economic impacts of non-native species in either the boreal zone or in Canada as a whole. In the few cases where management measures have been implemented for highly destructive non-native species, results have been somewhat successful, especially where classical biological control measures have been implemented against insects on trees. Chemical and mechanical management measures have had only limited success in localized situations. Management resources are most effectively applied to reducing the risk of introduction. The risk to the boreal zone posed by future new non-native species is increasing with the warming climate and the fast and direct transport of goods into the boreal zone from points of origin. Five recommendations are provided to address recognized gaps concerning non-native species. Key words: boreal, non-native species, ecological impacts, risk, biological invasion. On a enregistre plus de 1180 especes non indigenes, surtout d'origine palearctique, dans la zone de la foret boreale du Canada, dont la plus grande diversite se retrouve sur l'ile de Terre-Neuve et dans la zone boreale meridionale de l'Ontario et du Quebec. Le biote non indigene de la zone boreale (et du Canada en general) est mal connu en ce qui concerne sa composition et sa distribution. Une forte proportion des especes est associee a des habitats perturbes par l'homme comme les milieux urbains, les paysages agricoles, les corridors de communication et de transport ainsi que les developpements industriels. Les habitats naturels de la zone boreale montrent un fort degre de resistance a l'invasion, comparativement a ceux d'autres zones du Canada, vraisemblablement a cause des climats rigoureux, des faibles degres d'illumination, de la faible disponibilite des nutriments du sol, du faible pH des sols, de la faible productivite, et de la dense couverture du sol par les plantes, surtout les bryophytes. Parmi les peu nombreuses especes ayant colonise avec succes la zone boreale, plusieurs connaissent un fort declin en abondance apres quelques annees suggerant une resilience biotique. A date, la zone boreale a montre les moindres resistances et resiliences chez les grands vertebres (orignaux et cerf de Virginie) transferes sur ces iles, les maladies des vertebres et les vers de terre. En general, on a peu etudie les impacts ecologiques des especes non indigenes de la zone boreale et il y a peu d'exemples oU ces impacts sont evidents. De meme, il y a eu peu de tentatives pour quantifier les impacts economiques des especes non indigenes, que ce soit en zone boreale ou au Canada en general. Dans les rares cas oU des mesures d'amenagement ont ete mises en place pour les especes non indigenes fortement destructives, les resultats ont eu assez de succes, surtout la oU les mesures de maitrise biologique classique ont ete utilisees contre les insectes et les arbres. Les mesures chimiques et mecaniques n'ont qu'un succes limite dans des situations localisees. Les ressources de l'amenagement sont plus efficaces lorsqu'elles sont appliquees pour reduire le risque d'introduction. Le risque pour la foret boreale pose par de futures especes non indigenes augmente avec le rechauffement climatique et le transport rapide et direct de marchandises dans la zone boreale, a partir de leurs points d'origine. Les auteurs font cinq recommandations pour prendre en compte les lacunes reconnues au sujet des especes non indigenes. [Traduit par la Redaction] Mots-cles: boreal, especes non indigenes, impacts ecologiques, risque, invasion biologique., 1. Introduction Since the Wisconsinan glacial maximum ~21400 years ago, the rate of change of species composition in Canada has been determined by natural processes such as the rate and [...]

A growing body of work examines the direct and indirect effects of climate change on ecosystems, typically by using manipulative experiments at a single site or performing meta‐analyses across many independent experiments. However, results from single‐site studies tend to have limited generality. Although meta‐analytic approaches can help overcome this by exploring trends across sites, the inherent limitations in combining disparate datasets from independent approaches remain a major challenge. In this paper, we present a globally distributed experimental network that can be used to disentangle the direct and indirect effects of climate change. We discuss how natural gradients, experimental approaches, and statistical techniques can be combined to best inform predictions about responses to climate change, and we present a globally distributed experiment that utilizes natural environmental gradients to better understand long‐term community and ecosystem responses to environmental change. The warming and (species) removal in mountains (WaRM) network employs experimental warming and plant species removals at high‐ and low‐elevation sites in a factorial design to examine the combined and relative effects of climatic warming and the loss of dominant species on community structure and ecosystem function, both above‐ and belowground. The experimental design of the network allows for increasingly common statistical approaches to further elucidate the direct and indirect effects of warming. We argue that combining ecological observations and experiments along gradients is a powerful approach to make stronger predictions of how ecosystems will function in a warming world as species are lost, or gained, in local communities. [ABSTRACT FROM AUTHOR]

Invasional meltdowns, in which facilitation between species causes an accelerating increase in the number of introduced species or impacts, can cause large impacts in invaded systems. Earthworm invasion of northern forests has been suggested as a meltdown, with litter-dwelling species altering soil structure and facilitating mineral-soil or deep- burrowing earthworms that may be less capable of invading intact forest floors. We examined facilitation and synergistic effects of a litter-dwelling species (Dendrobaena octaedra Savigny, 1826) and a deep-burrowing species (Lumbricus terrestris L., 1758). Boreal forest soil cores were inoculated with D. octaedra, L. terrestris, both species, a higher density of L. terrestris, or no worms. After 4.5 months, we found no differences in survival or biomass between treatments for either species. Cocoon production did not differ for L. terrestris, but D. octaedra produced significantly fewer cocoons with L. terrestris. The two species had an additive effect on organic horizon depths and bulk densities. Thus, they did not appear to facilitate each other or have synergistic effects as would be predicted in an invasional meltdown. Les effondrements associes aux invasions, dans lesquels la facilitation entre les especes augmente le nombre D'especes introduites ou leurs impacts, peuvent avoir de fortes repercussions sur les systemes envahis. On a suggere que L'invasion des forets nordiques par les vers de terre est un effondrement dans lequel les especes vivant dans la litiere alterent la structure des sols et facilitent la presence de vers de terre des sols mineraux ou de ceux qui s'enfoncent profondement et qui peuvent etre moins capables d' envahir les sols forestiers intacts. Nous examinons la facilitation et les effets synergiques d'une espece vivant dans la litiere (Dendrobaena octaedra Savigny, 1826) et d'une autre qui s'enfonce profondement (Lumbricus terrestris L., 1758). Nous avons inocule des carottes de sol de foret boreale soit avec D. octaedra, L. terrestris, les deux especes, une plus forte densite de L. terrestris, ou alors aucun ver. Au bout de 4,5 mois, il n'y a aucune difference de survie ou de biomasse des deux especes entre les traitements. La production de cocons ne differe pas chez L. terrestris, mais D. octaedra produit significativement moins de cocons en presence de L. terrestris. Les deux especes ont un effet additif sur la densite brute et la profondeur de l'horizon organique. Ainsi, elles ne semblent pas se faciliter l'une l'autre, ni avoir d'effets synergiques comme on l'aurait predit dans le cas d'un effondre-ment lie aux invasions. [Traduit par la Redaction], Introduction The frequency and geographic extent of biological invasions are increasing worldwide, to the detriment of many native taxa (Cohen and Carlton 1998; Ricciardi 2001; Lockwood et al. 2007). With [...]

The invasion of jumping worms, a small group of pheretimoid earthworm species from Asia, has increasingly become an ecological, environmental and conservation issue in forest ecosystems and urban-suburban landscapes around the world. Their presence is often noticed due to their high abundance, distinctive "jumping" behavior, and prominent granular casts on the soil surface. Although they are known to affect soil carbon dynamics and nutrient availability, no single paper has summarized their profound impacts on soil biodiversity, plant community, and animals of all trophic groups that rely on soil and the leaf litter layer for habitat, food, and shelter. In this study, we summarize the biology, invasion, and ecological impacts of invasive jumping worms across North America. We highlight potential impacts of this second wave of earthworm invasion, contrast them with the preceding European earthworm invasion in temperate forests in North America, and identify annual life cycle, reproductive and cocoon survival strategies, casting behavior and co-invasion dynamics as the key factors that contribute to their successful invasion and distinct ecological impacts. We then suggest potential management and control strategies for practitioners and policy makers, underscore the importance of coordinated community science projects in tracking the spread, and identify knowledge gaps that need to be addressed to understand and control the invasion. [ABSTRACT FROM AUTHOR]

Motivation and aim: Soil biodiversity is central to ecosystem function and services. It represents most of terrestrial biodiversity and at least a quarter of all biodiversity on Earth. Yet, research into broad, generalizable spatial and temporal patterns of soil biota has been limited compared to aboveground systems due to complexities of the soil system. We review the literature and identify key considerations necessary to expand soil macroecology beyond the recent surge of global maps of soil taxa, so that we can gain greater insight into the mechanisms and processes shaping soil biodiversity. We focus primarily on three groups of soil taxa (earthworms, mycorrhizal fungi and soil bacteria) that represent a range of body sizes and ecologies, and, therefore, interact with their environment at different spatial scales. Results: The complexities of soil, including fine‐scale heterogeneity, 3‐D habitat structure, difficulties with taxonomic delimitation, and the wide‐ranging ecologies of its inhabitants, require the classical macroecological toolbox to be expanded to consider novel sampling, molecular identification, functional approaches, environmental variables, and modelling techniques. Main conclusions: Soil provides a complex system within which to apply macroecological research, yet, it is this property that itself makes soil macroecology a field ripe for innovative methodologies and approaches. To achieve this, soil‐specific data, spatio‐temporal, biotic, and abiotic considerations are necessary at all stages of research, from sampling design to statistical analyses. Insights into whole ecosystems and new approaches to link genes, functions and diversity across spatial and temporal scales, alongside methodologies already applied in aboveground macroecology, invasion ecology and aquatic ecology, will facilitate the investigation of macroecological processes in soil biota, which is key to understanding the link between biodiversity and ecosystem functioning in terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

In total, 42 collections were taken from Watson Lake to Dawson City and produced two species new to the Yukon: Eiseniella tetraedra and Lumbricus castaneus. The collections near Watson Lake, which is in the southeastern portion of the territory, were taken during the 2019 Yukon Conservation Data Centre Bioblitz. This brings the number of known species in the Yukon to ten. A collection in Kluane National Park produced the second sample of Arctiostrotus fontinalis in the territory. Bimastos parvus from Dawson City was also the second collection in the Yukon since the first in 1993. The most frequently encountered species in the Yukon are Dendrobaena octaedra and Dendrodrilus rubidus. Lumbricus rubellus is the first earthworm species to be reported from the Skagway area in Alaska. We present a key and illustrated glossary to the species in the Yukon. [ABSTRACT FROM AUTHOR]

Human activities are accelerating global biodiversity change and have resulted in severely threatened ecosystem services. A large proportion of terrestrial biodiversity is harbored by soil, but soil biodiversity has been omitted from many global biodiversity assessments and conservation actions, and understanding of global patterns of soil biodiversity remains limited. In particular, the extent to which hotspots and coldspots of aboveground and soil biodiversity overlap is not clear. We examined global patterns of these overlaps by mapping indices of aboveground (mammals, birds, amphibians, vascular plants) and soil (bacteria, fungi, macrofauna) biodiversity that we created using previously published data on species richness. Areas of mismatch between aboveground and soil biodiversity covered 27% of Earth's terrestrial surface. The temperate broadleaf and mixed forests biome had the highest proportion of grid cells with high aboveground biodiversity but low soil biodiversity, whereas the boreal and tundra biomes had intermediate soil biodiversity but low aboveground biodiversity. While more data on soil biodiversity are needed, both to cover geographic gaps and to include additional taxa, our results suggest that protecting aboveground biodiversity may not sufficiently reduce threats to soil biodiversity. Given the functional importance of soil biodiversity and the role of soils in human well‐being, soil biodiversity should be considered further in policy agendas and conservation actions by adapting management practices to sustain soil biodiversity and considering soil biodiversity when designing protected areas. Article impact statement: Given the importance of soil biodiversity for human well‐being, it should be considered in conservation policy and actions. [ABSTRACT FROM AUTHOR]

Human impacts are causing an unprecedented change of biodiversity across scales. To quantify the nature and degree of the biodiversity change, there have been a number of meta-analysis studies investigating the effects of global change drivers (land use, climate, etc.). However, these studies include few primary literature studies of soil biodiversity. Soil biodiversity is important for a variety of ecosystem services that are critical for human wellbeing. Yet, we know little about how soil organisms may respond to changing environmental conditions. Although studies have investigated the impact of global change drivers on soil biodiversity, they lack sufficient depth in the number of drivers and/or taxa included. Additionally, the previous focus on aboveground organisms has also resulted in a bias towards certain global change drivers in the primary literature. For example, climate change and land use change are more often studied, whilst pollution is typically understudied as a global change driver. Building on previous studies, we will conduct a meta-analysis to compare the effects of global change drivers (land use, habitat fragmentation/loss, fire, climate change, invasive species, pollution, and nutrient enrichment) on soil fauna (micro- to macro-invertebrates). This project aims to fill the current gaps in the literature, and actively participate in incorporating soil biodiversity into future global biodiversity assessments, by creating the first global open-acess dataset on the impacts of multiple global change drivers on soil fauna. [ABSTRACT FROM AUTHOR]

European earthworms were introduced to North America by European settlers about 400 years ago. Human-mediated introductions significantly contributed to the spread of European species, which commonly are used as fishing bait and are often disposed deliberately in the wild. We investigated the genetic structure of Lumbricus terrestris in a 100 km range south of Calgary, Canada, an area that likely was devoid of this species two decades ago. Genetic relationships among populations, gene flow, and migration events among populations were investigated using seven microsatellite markers and the mitochondrial 16S rDNA gene. Earthworms were collected at different distances from the city and included fishing baits from three different bait distributors. The results suggest that field populations in Alberta established rather recently and that bait and field individuals in the study area have a common origin. Genetic variance within populations decreased outside of the urban area, and the most distant populations likely originated from a single introduction event. The results emphasise the utility of molecular tools to understand the spatial extent and connectivity of populations of exotic species, in particular soil-dwelling species, that invade native ecosystems and to obtain information on the origin of populations. Such information is crucial for developing management and prevention strategies to limit and control establishment of non-native earthworms in North America. [ABSTRACT FROM AUTHOR]

Globally, biological invasions can have strong impacts on biodiversity as well as ecosystem functioning. While less conspicuous than introduced aboveground organisms, introduced belowground organisms may have similarly strong effects. Here, we synthesize for the first time the impacts of introduced earthworms on plant diversity and community composition in North American forests. We conducted a meta-analysis using a total of 645 observations to quantify mean effect sizes of associations between introduced earthworm communities and plant diversity, cover of plant functional groups, and cover of native and non-native plants. We found that plant diversity significantly declined with increasing richness of introduced earthworm ecological groups. While plant species richness or evenness did not change with earthworm invasion, our results indicate clear changes in plant community composition: cover of graminoids and non-native plant species significantly increased, and cover of native plant species (of all functional groups) tended to decrease, with increasing earthworm biomass. Overall, these findings support the hypothesis that introduced earthworms facilitate particular plant species adapted to the abiotic conditions of earthworm-invaded forests. Further, our study provides evidence that introduced earthworms are associated with declines in plant diversity in North American forests. Changing plant functional composition in these forests may have long-lasting effects on ecosystem functioning. [ABSTRACT FROM AUTHOR]

Earthworms are a key group of detritivores and ecosystem engineers in many ecosystems worldwide, yet we have a limited understanding of how their diversity varies globally. Synthesis of global data on earthworms would allow a range of important ecological, evolutionary, and applied questions to be addressed. We conducted a survey on global earthworm data at the 10th International Symposium on Earthworm Ecology (ISEE10) and sent an electronic survey to additional earthworm researchers. Respondents were asked about existing databases, research interests, required data, and research locations. Most researchers were aware of at least one database with earthworm data, with a total of 19 current databases being identified. Most of the top questions listed by researchers related to distributions and diversity at global scales, but traits, evolution, genetics, taxonomy, invasions, ecosystem functioning/impacts, ecotoxicology, and bioindicators were also key themes of interest. Correspondingly, distributional, environmental, and trait data were the primary data types required. Global data coverage was poor, with research being especially concentrated in Europe and the United States. Encouragingly, all researchers who currently had data indicated they would be willing to contribute it to a global database. While there are a number of key challenges associated with synthesis of earthworm data on a global scale (data limitations, taxonomic inconsistencies, logistical issues), the wide range of questions involving global data listed by researchers, and their willingness to contribute their own data, suggests there is strong interest in developing a comprehensive global database on earthworms. [ABSTRACT FROM AUTHOR]

Given the substantial impacts of non-native species on invaded systems, an understanding of the rates and spatial patterns of invasive spread is critical. Spread may vary across spatial scales, with dispersal of invasive species occurring both via diffusive spread at local sites and long-distance jump dispersal at larger scales. Research on earthworm invasions in North American forests has focused on patterns of spread across landscapes, with less examination of spread at local sites. We sampled the exotic earthworm Dendrobaena octaedra (Savigny, 1826) on 500 m × 500 m grids at three sites in the boreal forest of northeastern Alberta in 2006 and again in 2012-2013 to examine distributional changes over time. Earthworms spread farther from roads (the presumed site of initial introduction) over time, and spatial patterns at our sites suggest transport by vehicles and waterways are key vectors of dispersal at the local level. Spread was estimated to be occurring at a rate of at least 17.9 m/year. Our study indicates that both diffusive spread and jump dispersal of earthworms can be important at local scales and that local diffusive spread may be substantially higher than previously estimated. [ABSTRACT FROM AUTHOR]

In forest ecosystems, earthworms and wildfire are two ecological agents that cause carbon (C) stored in the forest floor to be transferred to the atmosphere as greenhouse gases, either through heterotrophic respiration (earthworms) or through periodical combustion (wildfire). For centuries, wildfire has been an important ecological driver in the boreal forests of Canada where most fire emissions to the atmosphere originate from the forest floor. In contrast, earthworms are recent invaders, having been introduced to the Canadian boreal during the 20th century. Their spread is mainly associated with anthropogenic activities. We examined stand-level effects of earthworms and wildfire on forest floor C by adapting an earthworm-C simulation model for the boreal and using it in combination with a forest C accounting model. Because the overall impact of an invasive species depends on its areal extent, we used a spatial model of earthworm spread to calculate the total predicted change in C storage at the landscape-level following earthworm invasions in northeastern Alberta. Depending on the ecological groups of earthworms modelled in stand-level simulations, the forest floor C stock was reduced by 49.7-94.3% after 125 years, although the majority of this reduction occurred 35-40 years after initiation of the invasion. Because earthworm activities reduced the amount of forest floor C available for burning, emissions from wildfire were lower in the presence of earthworms. Spatial modelling of earthworm effects within the 5,905,400 ha Alberta-Pacific Forestry Management Area projected that forest floor C stocks in the invaded stands decreased 50,875 Mg C by 2006, and 2,706,354 Mg C by 2056, compared with the same area if earthworms were not present. Loss of forest floor C averaged over the 50 year simulation was 10 g m² yr−1; similar in magnitude to estimates for C loss in the Canadian boreal due to wildfire or harvesting. These results indicate effects of non-native earthworms on the forest floor should be included in predictions of forest ecosystem C budgets to ensure accurate attribution of emissions to heterotrophic respiration versus combustion. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing 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.)

More than 1180 non-native species, mostly of Palaearctic origin, have been recorded from the boreal zone of Canada, with the highest diversity on the island of Newfoundland and in the southern boreal zone of Ontario and Quebec. The non-native biota of the boreal zone (and of Canada in general) is poorly known in terms of species composition and distribution. A large proportion of species are associated with disturbed anthropogenic habitats such as urban areas, agricultural landscapes, transportation and communication corridors, and industrial developments. Natural habitats in the boreal zone have a high degree of resistance to invasion compared with those of other Canadian zones, likely owing to harsh climates, low light levels, poor soil nutrient availability, low soil pH, low productivity, and dense covering of the ground by plants, especially bryophytes. Of the relatively few non-native species that have successfully colonized the boreal zone, many decline greatly in abundance after a few years, suggesting biotic resilience. To date the boreal zone has shown the least resistance and resilience to large vertebrates (moose and white-tailed deer) translocated to islands, diseases of vertebrates, and earthworms. In general, the ecological impacts of non-native species on the boreal zone have been poorly studied, and there are few examples where such impacts are evident. Likewise, there has been little attempt to quantify the economic impacts of non-native species in either the boreal zone or in Canada as a whole. In the few cases where management measures have been implemented for highly destructive non-native species, results have been somewhat successful, especially where classical biological control measures have been implemented against insects on trees. Chemical and mechanical management measures have had only limited success in localized situations. Management resources are most effectively applied to reducing the risk of introduction. The risk to the boreal zone posed by future new non-native species is increasing with the warming climate and the fast and direct transport of goods into the boreal zone from points of origin. Five recommendations are provided to address recognized gaps concerning non-native species. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Reviews is the property of Canadian Science Publishing 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.)

Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. [ABSTRACT FROM AUTHOR]

Ecologists are increasingly encouraged by funding agencies and professional societies to communicate their research with the public. However, most receive relatively little training in how to do this effectively. Furthermore, evaluation of whether such an investment by ecologists actually achieves conservation objectives is rare. We created an education program, involving print, television, radio, and internet media, to increase awareness about earthworm invasions and to discourage anglers from dumping earthworm bait. Using pre- and post-surveys, we evaluated our program's success in reaching its target audience and in changing knowledge and behavior. Few participants (4.1%) recalled seeing the program material and knowledge of the fact that earthworms are non-native in Alberta remained low (15.8% before, 15.1% after). Further, after being told about the negative effects of earthworms in forests, 46.7% of the anglers surveyed stated they would not change their bait disposal behavior in the future, with many commenting that they did not believe earthworms could be harmful. These results highlight the importance of evaluating education programs, rather than assuming they are successful. Given many participants' doubts that earthworms have negative effects, both regulations and education may be needed to reduce earthworm introductions. [ABSTRACT FROM AUTHOR]

: Ecosystem engineers affect other species by changing physical environments. Such changes may influence movement of organisms, particularly belowground where soil permeability can restrict dispersal. We investigated whether earthworms, iconic ecosystem engineers, influence microarthropod movement. Our experiment tested whether movement is affected by tunnels (i.e., burrows), earthworm excreta (mucus, castings), or earthworms themselves. Earthworm burrows form tunnel networks that may facilitate movement. This effect may be enhanced by excreta, which could provide resources for microarthropods moving along the network. Earthworms may also promote movement via phoresy. Conversely, negative effects could occur if earthworms alter predator-prey relationships or change competitive interactions between microarthropods. We used microcosms consisting of a box connecting a “source” container in which microarthropods were present and a “destination” container filled with autoclaved soil. Treatments were set up within the boxes, which also contained autoclaved soil, as follows: 1) control with no burrows; 2) artificial burrows with no excreta; 3) abandoned burrows with excreta but no earthworms; and 4) earthworms (Lumbricus rubellus) present in burrows. Half of the replicates were sampled once after eight days, while the other half were sampled repeatedly to examine movement over time. Rather than performing classical pairwise comparisons to test our hypotheses, we used AICc to assess support for three competing models (presence of tunnels, excreta, and earthworms). More individuals of Collembola, Mesostigmata, and all microarthropods together dispersed when tunnels were present. Models that included excreta and earthworms were less well supported. Total numbers of dispersing Oribatida and Prostigmata+Astigmata were not well explained by any models tested. Further research is needed to examine the impact of soil structure and ecosystem engineering on movement belowground, as the substantial increase in movement of some microarthropods when corridors were present suggests these factors can strongly affect colonization and community assembly. [ABSTRACT FROM AUTHOR]

Abstract: In North America, many species of European earthworms have been introduced to northern forests. Facilitative or competitive interactions between these earthworm species may result in non-additive effects on native plant and animal species. We investigated the combined versus individual effects of the litter-dwelling earthworm Dendrobaena octaedra Savigny, 1826 and the deep-burrowing species Lumbricus terrestris L., 1758 on microarthropod assemblages from boreal forest soil by conducting a mesocosm experiment. Soil cores from earthworm-free areas of northern Alberta, Canada, were inoculated with D. octaedra alone, L. terrestris alone, both worm species together, or no earthworms. After 4.5 months, microarthropods were extracted from the soil, counted, and identified to higher taxa. Oribatid mites were further identified to family and genus. Abundance of microarthropods was significantly lower in the treatment containing both species than in the no earthworm treatment and the L. terrestris treatment. Oribatida and Prostigmata/Astigmata differed significantly among treatments and were lowest in the treatment containing both earthworm species, followed by the D. octaedra treatment, although post-hoc pairwise comparisons were not significant. Within the Oribatida, composition differed between the control and L. terrestris treatments as compared to the D. octaedra and both-species treatments, with Suctobelbella and Tectocepheus in particular having higher abundances in the control treatment. Effects of the two earthworm species on microarthropods were neither synergistic nor antagonistic. Our results indicate that earthworms can have strong effects on microarthropod assemblages in boreal forest soils. Future research should examine whether these changes have cascading effects on nutrient cycling, microbial communities, or plant growth. [Copyright &y& Elsevier]

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Population genetic studies can help to determine whether invasive species are established via single vs. multiple introduction events and also to distinguish among various colonization scenarios. We used this approach to investigate the introduction of Dendrobaena octaedra, a non-native earthworm species, to the boreal forest of northern Alberta. The spread of non-native earthworms in forested systems is not well understood, although bait abandonment and vehicular transport are believed to be important. Mitochondrial DNA sequencing revealed that multiple introductions of this species have occurred in northern Alberta, although individual populations may have been established by either single or multiple invaders introduced on one or more occasions. There was no relationship between genetic distances and either geographical distances or distances along road networks, suggesting that human-mediated jump dispersal is more common than diffusive spread via road networks or via active dispersal. As well, genetic diversity was significantly greater at boat launches than roads, indicating that multiple introductions may be more likely to occur at those locations. Focusing management efforts on areas where multiple introductions are likely to occur may help to reduce invasive species’ potential for adaptive evolution and subsequent rapid spread. [ABSTRACT FROM AUTHOR]

Trophic interactions within food webs affect species distributions, coexistence, and provision of ecosystem services but can be strongly impacted by climatic changes. Understanding these impacts is therefore essential for managing ecosystems and sustaining human well‐being. Here, we conducted a global synthesis of terrestrial, marine, and freshwater studies to identify key gaps in our knowledge of climate change impacts on food webs and determine whether the areas currently studied are those most likely to be impacted by climate change. We found research suffers from a strong geographic bias, with only 3.5% of studies occurring in the tropics. Importantly, the distribution of sites sampled under projected climate changes was biased—areas with decreases or large increases in precipitation and areas with low magnitudes of temperature change were under‐represented. Our results suggest that understanding of climate change impacts on food webs could be broadened by considering more than two trophic levels, responses in addition to species abundance and biomass, impacts of a wider suite of climatic variables, and tropical ecosystems. Most importantly, to enable better forecasts of biodiversity responses to climate change, we identify critically under‐represented geographic regions and climatic conditions which should be prioritized in future research. [ABSTRACT FROM AUTHOR]