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Variable retention forest harvesting aims to reduce negative effects of harvesting on forest biodiversity, but knowledge gaps remain regarding its effects on some taxa over longer post-harvest time frames. To better understand effects of variable retention and environmental features on amphibians, we used pitfall traps to capture wood frogs (Lithobates sylvaticus (LeConte, 1825)) across four levels of retention (clearcut (0%), 20%, 50%, and unharvested control (100%)), and two forest types (deciduous and coniferous), in 17-year post-harvest forests in northwest Alberta. We mapped breeding sites and used a LiDAR-based terrain moisture index (depth-to-water) to examine relationships between relative abundance, breeding site proximity, and soil moisture. Retention level alone had no effect on relative abundance of adult wood frogs, but in late summer (July and August), there was a significant interaction between retention level and forest type: capture rates decreased with retention level for deciduous forests, but increased with retention level in conifer forests. During late summer, capture rates were higher in conifer forests than deciduous forests, with soil moisture (lower depth-to-water) positively related to capture rates. Though timber retention may be beneficial to wood frogs in the short term, any impacts of forest harvesting on wood frog abundance were undetectable in stands 17 years post-harvest. Key words: variable retention, forestry, anuran amphibians, wood frog, Lithobates sylvaticus, post-harvest regeneration, LiDAR, depth-to-water, Introduction The Boreal Forest is one of the largest forest biomes in the world, representing approximately 75% of the productive forest in Canada, as defined by a forest's ability to [...]

In peatlands, microtopography strongly affects understory plant communities. Disturbance can result in a loss of microtopographic variation, primarily through the loss of hummocks. To address this, mounding treatments can be used to restore microtopography. We examined the effects of mounding on the understory vegetation on seismic lines in wooded fens. Seismic lines are deforested linear corridors (~3 to 8 m wide) created for oil and gas exploration. Our objectives were to compare the recovery of understory communities on unmounded and mounded seismic lines and determine how recovery varies with microtopographic position. Recovery was evident in the unmounded seismic lines, with higher shrub and total understory cover at the 'tops' of the small, natural hummocks than at lower microtopographic positions--much like the trends in adjacent treed fens. In contrast, mounding treatments that artificially created hummocks on seismic lines significantly changed understory communities. Mounded seismic lines had higher forb cover, much lower bryophyte cover, less variation along the microtopographic gradient, and community composition less similar to that of the reference sites than unmounded seismic lines due to higher abundance of marsh-associated species. Our results suggest that mounding narrow seismic lines can be detrimental to the recovery of the understory communities in treed peatlands. Key words: moderate-rich fens, linear disturbances, mounding, restoration, understory vegetation. Dans les tourbieres, la microtopographie influence fortement les communautes vegetales de sous-etage. Une perturbation peut entrainer une baisse de variation de la microtopographie, surtout par la perte de monticules. Pour resoudre ce probleme, la creation de monticules peut etre utilisee pour restaurer la microtopographie. Nous avons etudie les effets de la creation de monticules sur la vegetation de sous-etage dans des lignes sismiques traversant des tourbieres boisees. Les lignes sismiques sont des couloirs lineaires deboises (environ 3 a 8 m de large), crees pour l'exploration petroliere et gaziere. Nos objectifs etaient de comparer le retablissement des communautes de sous-etage dans des lignes sismiques avec et sans creation de monticules, et de determiner comment le retablissement varie en fonction de la position microtopographique. Le retablissement etait manifeste dans les lignes sismiques sans creation de monticules, ou le recouvrement d'arbustes et de vegetation totale sur le dessus de petits monticules naturels etait plus grand qu'aux positions microtopographiques inferieures, ce qui tendait aussi a etre le cas dans les tourbieres boisees adjacentes. En revanche, la creation artificielle de monticules dans les lignes sismiques a considerablement change les communautes de plantes de sous-etage. Les lignes sismiques avec des monticules artificiels avaient un recouvrement de plantes herbacees plus eleve, un recouvrement de bryophytes beaucoup plus faible, moins de variation le long du gradient microtopographique, et une composition de la vegetation moins semblable a celle des stations de reference que celle des lignes sismiques non traitees, en raison d'une plus grande abondance d'especes associees aux marais. Nos resultats indiquent que la creation de monticules dans les lignes sismiques etroites peut nuire au retablissement des communautes de plantes de sous-etage dans les tourbieres boisees. [Traduit par la Redaction] Mots-cles: tourbieres moderement riches, perturbations lineaires, creation de monticules, restauration, vegetation de sous-etage., Introduction Forests across the world are experiencing increases in the levels of human disturbance that are influencing their ecological function and biodiversity (Haddad et al. 2015). In regions with oil [...]

The world's forests are highly fragmented by linear disturbances, and many forests have failed to recover decades after abandonment. Lack of recovery is common in unproductive forests, such as treed peatlands, because of conditions that limit tree growth, including simplification of microtopography (loss of microsites). The persistence of these features affects biodiversity, but of particular concern in Canada is the detrimental effects on threatened woodland caribou. Although natural regeneration of trees in peatlands occurs in some places, it is not an effective recovery strategy for restoring the habitat of woodland caribou. This has led to restoration activities with costs exceeding CAD$12 500/km. However, current restoration does not consider wildfires, which can destroy planted trees but also initiate early seral conditions that favor natural regeneration. Here we compared tree regeneration on seismic lines and adjacent forest controls for burnt (75 sites) and unburnt (68 sites) treed peatlands in northeast Alberta, Canada. Tree regeneration (stems with a DBH < 1 cm/ha) varied from 28 500 in burnt lines, 11440 in unburnt lines, and 18 210 in burnt forest, to 9520 in unburnt forest. Wildfires promoted denser regeneration in sites with a greater proportion of serotinous species and water table depth. Microtopography and terrain wetness explained regeneration on burnt lines, but not unburnt lines. In burnt and unburnt lines, sunlight, microtopography, and depth of water table most affected tree regeneration patterns. Key words: seismic line, linear disturbance, boreal forest, wildfire, forest gap. Les forets du monde sont tres fragmentees par les perturbations lineaires et plusieurs de ces forets n'ont pas encore reussi a recuperer meme si elles sont abandonnees depuis des decennies. L'absence de recuperation est frequente dans les forets improductives telles que les tourbieres boisees a cause des conditions qui limitent la croissance des arbres, incluant l'uniformisation de la microtopographie (perte de microsites). La persistance de ces caracteristiques est nefaste pour la biodiversite et le Canada est particulierement inquiet des effets prejudiciables pour le caribou des bois qui est menace. Bien que les arbres se regenerent naturellement dans certaines tourbieres, ce n'est pas une strategie efficace de recuperation pour restaurer l'habitat du caribou des bois. Cela a entraine des activites de restauration dont les couts excedent 12 500 $CAN/km. Cependant, la restauration actuelle ne tient pas compte des feux de foret qui peuvent detruire les plantations d'arbres, mais aussi instaurer des conditions de debut de succession qui favorisent la regeneration naturelle. Dans cet article, nous comparons la regeneration arborescente dans les lignes sismiques et les forets temoins adjacentes dans le cas de tourbieres boisees qui ont brule (75 sites) ou non (68 sites) dans le nord-est de l'Alberta, au Canada. La regeneration arborescente (tiges avec un DHP < 1 cm/ha) varie de 28 500 tiges dans les lignes qui ont brule, a 11440 dans celles qui n'ont pas brule, a 18 210 dans les forets qui ont brule et a 9520 dans celles qui n'ont pas brule. Les feux de foret ont favorise l'apparition d'une regeneration plus dense dans les sites oU la proportion d'especes serotineuses est plus elevee et la nappe phreatique plus basse. La microtopographie et l'humidite du terrain expliquent la regeneration dans les lignes qui ont brule mais pas dans celles qui n'ont pas brule. Dans les lignes qui ont brule ou non, l'ensoleillement, la microtopographie et la profondeur de la nappe phreatique ont le plus d'impact sur les patrons de la regeneration arborescente. [Traduit par la Redaction] Mots-cles: ligne sismique, perturbation lineaire, foret boreale, feu de foret, trouee forestiere., Introduction The world's forests are being increasingly fragmented from anthropogenic disturbances, including linear disturbances associated with, among other things, roads, transmission lines, pipelines, and oil and gas exploration. Indeed, the [...]

Wildfire is the predominant natural disturbance in the boreal forests of western Canada. Natural disturbance based forest management involves the use of retention harvesting to retain stand structural diversity after harvest; however, unlike fire, this partial harvesting technique does not cause combustion of the forest floor. Application of prescribed burning to areas treated with retention harvesting might emulate the influence of wildfires more effectively than harvesting alone. We compared understory vascular plant diversity, abundance, and composition between forest stands subjected to dispersed retention harvesting (10% retention) with and without prescribed burning 1, 6, and 11 or 12 years after burning. Untreated forest was included as a reference. Research was conducted in conifer-dominated, mixedwood, and deciduous-dominated boreal forest stands in northwestern Alberta, Canada. In deciduous-dominated stands, burned areas of retention harvested stands had higher species richness and greater cover than did unburned areas. In all three forest cover types, effects of harvest with and without burn on species richness, cover, and composition were still evident a decade after disturbance. Fire-adapted species benefited most from the prescribed burn treatment. The combination of prescribed burning with retention harvesting can be considered a useful option in forest management that aims to emulate natural disturbance. Key words: prescribed burning, retention harvesting, fire, understory vascular plants, boreal forest. Les perturbations qui dominent dans les forets boreales de l'ouest du Canada sont causees par les feux de foret. L'amenagement forestier qui s'inspire des perturbations naturelles inclut l'utilisation de la coupe avec retention pour conserver la diversite structurale a la suite de la recolte. Cependant, cette methode de coupe partielle n'entraine pas la combustion de la couverture morte comme c'est le cas avec le feu. Le recours au brulage dirige dans les zones soumises a une coupe avec retention pourrait imiter l'effet des feux de foret plus efficacement que la coupe seule. Nous avons compare la composition, l'abondance et la diversite des plantes vasculaires en sous-etage dans des peuplements forestiers soumis a une coupe avec retention des arbres disperses (10 % de retention) avec et sans brulage dirige 1, 6 et 11 ou 12 ans apres le brulage. Une foret non traitee a ete incluse comme reference. Cette etude a ete realisee dans le nord-ouest de l'Alberta, au Canada, dans des peuplements de foret boreale domines soit par des resineux soit par des feuillus et dans des peuplements mixtes. Dans les peuplements domines par des feuillus soumis a une coupe avec retention, la richesse en especes et la couverture etaient plus grandes dans les zones brulees que dans les zones non brulees. Dans les trois types de couvert forestier, les effets de la recolte avec et sans brulage sur la richesse en especes, la couverture et la composition etaient encore evidents 10 ans apres la perturbation. Les especes adaptees au feu ont le plus beneficie du brulage dirige. La combinaison du brulage dirige et de la coupe avec retention peut etre consideree comme une option utile pour l'amenagement forestier qui cherche a imiter les perturbations naturelles. [Traduit par la Redaction] Mots-cles: brulage dirige, coupe avec retention, feu, sous-etage, plantes vasculaires, foret boreale., Introduction Wildfire is the predominant stand-replacing natural disturbance in the boreal forest and it drives the region's vegetation dynamics (Johnson 1992; Payette 1992). The understory vegetation layer hosts most of [...]

Understanding how maximum canopy height is related to forest community assembly is essential yet largely unexplored. Maximum canopy height is affected by competition and abiotic environmental factors through different ecological processes (e.g. niche differentiation and environmental filtering), as well as historical or stochastic factors. However, little has been done to empirically examine the ecological processes that influence maximum canopy height. We set out to examine the relationship between maximum canopy height and community phylogenic structure. We surveyed maximum canopy heights from a regional dataset of forest plots (466 sites of 50 m × 50 m) from the boreal forest of northeastern Alberta, Canada. We then explored the relationships between maximum canopy height as measured by airborne LiDAR (Light Detection and Ranging) and the phylogenetic structure of seed plants, represented by net relatedness index and nearest taxa index. We found stronger phylogenetic clustering among major evolutionary clades for communities with higher maximum canopy height, which implied that environmental filtering by abiotic factors is a driving factor for boreal forests. However, we also found stronger phylogenetic overdispersion within each clade for communities with higher maximum height, indicating more intense niche differentiation. Our results suggest that communities with higher maximum canopy height may have experienced more intense historical abiotic environmental filtering and recent niche differentiation in boreal forests. These findings will contribute to the monitoring and management of forest biodiversity. [ABSTRACT FROM AUTHOR]