Transforming Abandoned Farm Fields to Conifer Plantations Reduces Ruffed Grouse Density

Natural forests likely will be unable to fulfill society’s needs sustainably for wood fiber in the near future. In an attempt to meet increasing demands while protecting intact forests, producers have increasingly considered alternative sources of timber, such as intensively managed plantations. In regions that are economically dependent on forest harvesting, abandoned farm fields are often targeted for conversion to intensive coniferous plantations. These sites are generally in an early successional stage that is dominated by deciduous stands, which provide an important habitat type for several game species, including ruffed grouse (Bonasa umbellus). Therefore, conversion could represent a loss of habitat for this species and several others that are associated with early successional deciduous stages. We conducted grouse drumming surveys in northwestern Quebec, Canada to evaluate the effects of transforming old fields into conifer plantations on ruffed grouse by comparing densities between two habitat types: abandoned farm fields (n = 22) and old fields converted to conifer plantations (n = 19). To correct anyaudibility bias between habitat types, we located all drumming males that were heard at each site. We then analyzed the number of individuals that were detected in the sites with repeated count models. Our results show that overall drumming males avoided plantations. Overhead cover increased drumming male densities in both habitat types, whereas lateral cover increased drumming grouse densities only in plantations. The density of deciduous stems and fruit-bearing stems also had a tendency to increase drumming male densities, but their effects were marginal. Most ruffed grouse in abandoned farm fields used piles of woody debris on the ground as drumming structures rather than large logs or rock outcrops. Our results suggest that plantations do not have the vegetative cover and quantity of food stems necessary to support high ruffed grouse densities during the drumming season and that conversion of abandoned farm fields to coniferous plantations may exert negative cascading effects for reproduction and population growth

Response of wild bee communities to beekeeping, urbanization, and flower availability

Wild bees provide pollination services and are currently declining at the global scale. A potential cause for this decline is competitive interactions with domestic honey bees. Urban beekeeping, a fairly new activity, is rapidly gaining popularity. In contrast with agricultural and natural areas, the extent of competition between honey bees and wild bees in urban areas is unclear. The objectives of this study were to quantify the impact of honey bees, urbanization, and the availability of floral resources on wild bee communities. We hypothesized that honey bees exert negative impacts on wild bees, that floral resources favor wild bee communities and mitigate the negative impacts of competition with honey bees, and that the influence of heat islands, used as a proxy for urbanization, varies between wild bees with their functional traits (nesting behavior). We tested these hypotheses with a data set of 19,077 wild bee specimens collected using colored pan-traps at 25 urban sites in 2012 and 2013. We investigated community and population patterns after accounting for imperfect detection probability. We found no evidence of competition between wild and domesticated bees. Our analyses indicate mixed effects of urban heat islands across species and positive effects of floral resources. We conclude that cities can allow the coexistence of urban beekeeping and wild bees under moderate hive densities. However, it will remain crucial to further investigate the competitive interactions between wild and honey bees to determine the threshold of hive densities beyond which competition could occur

Effects of Cambial Age and Stem Height on Wood Density and Growth of Jack Pine Grown in Boreal Stands

Jack pine specimens were examined for longitudinal and radial variations in selected wood quality parameters. Wood density and ring width of cross-sections were measured systematically from pith to bark along the merchantable stem using X-ray densitometry. Effects of cambial age and stem height were analyzed using a linear mixed model with two levels of nesting. A strong interaction between the two factors was found in corewood. Tree individual variation increased with cambial age for all studied wood properties and was larger in earlywood than in latewood. Radial patterns in the studied parameters closely approximated published ones in the lower stem but lessened considerably with increasing stem height. By contrast, longitudinal patterns reversed with cambial age in earlywood. High coordination was found between longitudinal patterns in corewood and radial patterns in the stem base, indicating a similar maturation pattern in the apical meristem and cambia. However, with increasing cambial age, this high coordination disappeared rapidly

Utilisation des parcs à résidus miniers par la sauvagine en comparaison avec des étangs de castors en Abitibi-Témiscamingue

Les milieux humides sont essentiels pour un grand nombre d’espèces fauniques et végétales. Ces milieux sont cependant dégradés par les activités humaines, affectant ainsi l’habitat de groupes d’espèces tels que la sauvagine, qui utilise ces milieux aux différentes étapes de son cycle de vie. Dans ce contexte particulier, certains milieux humides artificiels, tels que des bassins d’épuration ou de récupération d’eau de pluie, sont parfois utilisés par ces espèces en alternative à des habitats naturels perdus. Dans la région de l’Abitibi-Témiscamingue, localisée dans l’Ouest du Québec, certains étangs de parcs à résidus miniers sont connus par les ornithologistes pour être utilisés par plusieurs espèces aviaires. Dans le cadre de cette étude, nous nous sommes intéressés à évaluer la qualité des parcs à résidus miniers en comparaison avec un milieu naturel reconnu favorable à l’établissement de la sauvagine : des étangs de castors. Nous avons effectué un inventaire des espèces de sauvagine (adultes et couvées) présentes sur 12 étangs miniers et 38 étangs de castors situés en Abitbi-Témiscamingue. Nous avons également considéré les variables environnementales sur les sites pouvant affecter l’occupation de ces étangs. Les comparaisons effectuées entre les deux types de sites ont montré que les conditions sur les sites miniers semblent aussi favorables à l’établissement de la sauvagine en période de reproduction que celles observées sur les étangs de castors. En utilisant les modèles d’occupation de sites, nous avons trouvé que la plupart des espèces utilisaient autant les parcs à résidus miniers que les étangs de castors considérés. Ces espèces semblent également se reproduire autant sur les deux types de sites. Les adultes et les couvées du Garrot à oeil d’or semblent même utiliser de façon plus importante les étangs miniers. Bien que nos modèles n’aient pas permis de montrer de relation directe entre l’occupation du garrot et les conditions observées sur les sites, nous suggérons que les résultats obtenus pour le garrot peuvent s’expliquer par le fait que les étangs miniers sont plus ouverts et souvent dépourvus de poissons compétiteurs. Ces caractéristiques sont donc à favoriser lors de la restauration d’un site minier dans le cas d’un aménagement pour la sauvagine. Puisque ces étangs miniers sont également utilisés par plusieurs espèces, nous recommandons de conserver ces éléments du paysage, qui peuvent représenter un nouvel habitat de qualité pour ce groupe faunique. De futuresétudes réalisées sur l’utilisation des étangs miniers par la sauvagine devraient être effectuées afin de confirmer ces conclusions sur le long terme

Using dynamicN-mixture models to test cavity limitation on northern flying squirrel demographic parameters using experimental nest box supplementation

Dynamic N-mixture models have been recently developed to estimate demographic parameters of unmarked individuals while accounting for imperfect detection. We propose an application of the Dail and Madsen (2011: Biometrics, 67, 577–587) dynamic N-mixture model in a manipulative experiment using a before-after control-impact design (BACI). Specifically, we tested the hypothesis of cavity limitation of a cavity specialist species, the northern flying squirrel, using nest box supplementation on half of 56 trapping sites. Our main purpose was to evaluate the impact of an increase in cavity availability on flying squirrel population dynamics in deciduous stands in northwestern Quebec with the dynamic N-mixture model. We compared abundance estimates from this recent approach with those from classic capture–mark–recapture models and generalized linear models. We compared apparent survival estimates with those from Cormack–Jolly–Seber (CJS) models. Average recruitment rate was 6 individuals per site after 4 years. Nevertheless, we found no effect of cavity supplementation on apparent survival and recruitment rates of flying squirrels. Contrary to our expectations, initial abundance was not affected by conifer basal area (food availability) and was negatively affected by snag basal area (cavity availability). Northern flying squirrel population dynamics are not influenced by cavity availability at our deciduous sites. Consequently, we suggest that this species should not be considered an indicator of old forest attributes in our study area, especially in view of apparent wide population fluctuations across years. Abundance estimates from N-mixture models were similar to those from capture–mark–recapture models, although the latter had greater precision. Generalized linear mixed models produced lower abundance estimates, but revealed the same relationship between abundance and snag basal area. Apparent survival estimates from N-mixture models were higher and less precise than those from CJS models. However, N-mixture models can be particularly useful to evaluate management effects on animal populations, especially for species that are difficult to detect in situations where individuals cannot be uniquely identified. They also allow investigating the effects of covariates at the site level, when low recapture rates would require restricting classic CMR analyses to a subset of sites with the most captures

Habitat, Climate, and Fisher and Marten Distributions

Since the mid‐twentieth century, fisher populations (Pekania pennanti) increased in several eastern jurisdictions of North America, particularly in the northern part of the species’ range. Changes in fisher distribution have led to increased overlap with the southern portion of the range of American marten (Martes americana), whose populations may be locally declining. This overlap occurs particularly in habitats undergoing natural and anthropogenic modification. The objective of our study was to determine the respective effects of habitat changes and climatic conditions on fisher and marten populations in Quebec, Canada, based on trapper knowledge. We analyzed annual fisher and marten harvest (number of pelts sold/100 km2) between the 1984–1985 and 2014–2015 trapping seasons using linear mixed models. Fisher harvest increased with the increased abundance of mixed forests >12m tall, resulting from decades of forest harvesting. Fisher harvest decreased with increasing spring rains, which can affect survival when rearing young. Marten harvest decreased with increasing winter rains, which lower thermoregulation capacity and hamper movements by creating an ice crust on the snowpack, reducing access to subnivean areas. Decline in marten harvest during the 30‐year study period coincided with an increase in fisher harvest, suggesting possible interspecific competition. Results highlight that managers should strive to maintain mixedwood stands taller than 12m to maintain high quality habitat for fishers. Our study confirms the importance of working with trappers to assess furbearing population trends in response to habitat changes and climatic conditions

Site occupancy by American martens and fishers in temperate deciduous forests of Québec

Anglais Interspecific interactions can mediate site occupancy of sympatric species and can be a key factor in habitat use patterns. American martens (Martes americana) and Fishers (Pekania pennanti) are two sympatric mesocarnivores in eastern North American forests. Due to their larger size, fishers have a competitive advantage over martens. We investigated site occupancy of martens and fishers in temperate deciduous forests of Québec, an environment modified by forest management and climate change. We formulated hypotheses on the spatial distribution of the studied species based on the knowledge of local trappers and on the scientific literature regarding forest cover composition, habitat fragmentation, and competitive relationships. We used a network of 49 camera traps monitored over two fall seasons to document site occupancy by both species. We used two-species site occupancy models to assess habitat use and the influence of fishers on martens at spatial grains of different sizes. None of the habitat variables that we considered explained site occupancy by fishers. Availability of dense old coniferous stands explained the spatial distribution of martens both at the home range grain size and at the landscape grain size. We identified the characteristics of habitat hotspots based on the knowledge of trappers, which highlighted the importance of stand composition, height, age, and canopy closure. The characteristics of habitat hotspots for martens in temperate deciduous forests refine the habitat suitability model for American martens that was originally developed for boreal forests of Québec. Français Les interactions interspécifiques peuvent affecter l’occupation de sites par des espèces sympatriques et jouer un rôle clé dans leur utilisation des habitats. La martre d’Amerique (Martes americana) et le pékan (Pekania pennanti) sont deux mésocarnivores sympatriques des forêts de l’est de l’Amérique du Nord. En raison de sa grande taille, le pékan est un compétiteur dominant de la martre. Nous avons étudié l’occupation des sites par la martre et le pékan dans la forêt tempérée feuillue du Québec, un environnement modifié par l’aménagement forestier et les changements climatiques. Nous avons formulé des hypothèses sur la répartition spatiale des espèces étudiées en nous basant sur les connaissances des trappeurs locaux et sur la littérature scientifique en ce qui a trait à la composition du couvert forestier, à la fragmentation de l’habitat, et aux relations de compétition. Nous avons utilisé un réseau de 49 appareils photo à déclenchement automatique pendant deux automnes pour documenter l’occupation des sites par les deux espèces. Nous avons utilisé des modèles d’occupation de sites à deux espèces afin d’évaluer l’effet de la présence du pékan sur l’utilisation de l’habitat par la martre à des échelles spatiales de résolutions variables. Aucune des variables d’habitat que nous avons prises en compte n’explique l’occupation des sites par les pékans. La disponibilité de vieux peuplements denses de conifères explique la répartition spatiale de la martre aux échelles spatiales du domaine vital et du paysage. Nous avons développé un indice d’habitat potentiel basé sur les connaissances des trappeurs, qui a mis en évidence l’importance de la composition, de la hauteur, de l’âge et de la densité des peuplements. Cet indice affine, pour les forêts tempérées feuillues du Québec, le modèle de qualité de l’habitat de la martre d’Amérique originellement élaboré pour la forêt boréale

Sugar maple (Acer saccharum March.) growth is influenced by close conspecifics and skid trait proximity following selection harvest

In this study, we quantified the effects of local neighbourhood competition, light availability, and proximity to skid trails on the growth of sugar maple (Acer saccharum Marsh.) trees following selection harvest. We hypothesized that growth would increase with decreasing competition and increasing light availability, but that proximity to skid trails would negatively affect growth. A total of 300 sugar maples were sampled 10 years after selection harvesting in 18 stands in Témiscamingue (Québec, Canada). Detailed tree and skid trail maps were obtained in one 0.4 ha plot per stand. Square-root transformed radial growth data were fitted to a linear mixed model that included tree diameter, crown position, a neighbourhood competition index, light availability (estimated using the SORTIE light model), and distance to the nearest skid trail as explanatory variables. We considered various distance-dependent or -independent indices based on neighbourhood radii ranging from 6 to 12 m. The competition index that provided the best fit to the data was a distance-dependent index computed in a 6 m search radius, but a\ud distance-independent version of the competition index provided an almost equivalent fit to data. Models corresponding to all combinations of main effects were fit to data using maximum likelihood, and weighted averages of parameter estimates were obtained usingmultimodel inference. All predictors had\ud an influence on growth, with the exception of light. Radial growth decreased with increasing tree diameter, level of competition and proximity to skid trails, and varied among crown positions with trees in suppressed and intermediate positions having lower growth rates than codominants and dominants. Our results indicate that in selection managed stands, the radial growth of sugarmaple trees depends on\ud competition from close (6 m) conspecific neighbours, and is still affected by proximity to skid trails 10 years after harvesting. Such results underscore the importance of minimizing the extent of skid trail networks by careful pre-harvest planning of trail layout. We also conclude that the impact of heterogeneity among individual-tree neighbourhoods, such as those resulting from alternative spatial patterns of harvest, can usefully be integrated into models of post-harvest tree growth

Peatlands and green frogs : a relationship regulated by acidity?

The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.Les répercussions des précipitations acides sur les populations d'amphibiens ont été intensivement étudiées au cours des deux dernières décennies. Néanmoins, les amphibiens en milieux naturellement acides, tels que les tourbières menacées par l'industrie de l'extraction de la tourbe, ont reçu très peu d'attention. Lors de deux études sur le terrain et d'une expérience, j'ai évalué l'utilisation de milieux tourbeux par la grenouille verte (Rana clamitans melanota), une espèce sensible à l'exploitation forestière et à l'extraction de la tourbe. J'ai d'abord comparé la fréquentation et la reproduction des grenouilles dans les étangs de tourbières à celles des étangs en milieu terrestre. J'ai ensuite caractérisé les mouvements des grenouilles entre les milieux tourbeux et les milieux forestiers adjacents, afin de déterminer s'ils correspondent à des migrations de reproduction ou d'après reproduction. Finalement, j'ai évalué lors d'une expérience menée sur le terrain la valeur des tourbières comme milieux de réhydratation pour les amphibiens : j'ai mis des grenouilles déshydratées en deça de leur perte vitale en eau en présence de sphaigne vivante et de deux substrats associés aux milieux non tourbeux (eau avec pH d'environ 6,5 et terre saturée en eau). La reproduction des grenouilles vertes dans les étangs de tourbière est un phénomène rare et aucun mouvement net de grenouilles vertes n'a été détecté entre les milieux forestiers et tourbeux. Néanmoins, les grenouilles temporairement déshydratées n'évitent pas la sphaigne. Malgré la faible probabilité de reproduction des grenouilles vertes dans les tourbières et l'absence de mouvements massifs entre les milieux forestiers et tourbeux, les grenouilles n'évitent pas les substrats tourbeux pour se réhydrater, malgré leur acidité. Ainsi, les tourbières offrent des habitats d'estivage aux amphibiens, ce qui souligne l'importance de ces milieux menacés dans l'écologie terrestre des amphibien