The forests of Newfoundland represent a unique type of boreal ecosystem with diverse environmental gradients that exercise strong control over disturbances and vegetation. We have assembled and analyzed a comprehensive database on disturbance history in Newfoundland. Defoliating insects, led by the eastern spruce budworm (Choristoneura fumiferana Clemens) and the hemlock looper (Lambdina fiscellaria Guenée), have the largest disturbance footprint on the island. Infrequent wildfires (fire cycle = 769 years) had a decisive role in driving forest succession, particularly in the Central Newfoundland Forest and Maritime Barrens ecoregions. We hypothesize that the historical disturbance regime in Newfoundland would not have enabled steady-state conditions, although the amount of old-growth forests and deadwood would likely have been greater than it is today. We argue that the implementation of the natural range of variation (NRV) concept in forest management for such non-equilibrium systems will be challenging in Newfoundland and in other regions of Canada. We propose guiding principles to adapt the NRV concept using ecological knowledge. If a sciencebased approach is desired, assumptions about NRV should be tested using a rigorous experimental design. We encourage the establishment of large-scale experiments in at least a portion of forestry operations to enable an ecosystem sciencebased approach.Keywords: natural disturbance, wildfire, insect defoliation, Newfoundland, ecosystem management, logging, ecological experiments RÉSUMÉ Les forêts de Terre-Neuve constituent un type particulier d' écosystème boréal qui présente divers gradients écologiques qui ont une influence marquée sur les perturbations et la végétation. Nous avons assemblé et analysé une base de données exhaustive sur l'historique des perturbations à Terre-Neuve. Les insectes défoliateurs, principalement la tordeuse des bourgeons de l' épinette (Choristoneura fumiferana Clemens) et l'arpenteuse de la pruche (Lambdina fiscellaria Guenée), sont ceux qui ont occasionné les plus fortes perturbations sur l'île. Les rares feux de forêt (cycle des feux = 769 ans) ont joué un rôle moteur dans la succession des peuplements forestiers, notamment dans les écorégions de la forêt du centre de Terre-Neuve et de la toundra des Maritimes. Nous posons l'hypothèse que le régime historique des perturbations de Terre-Neuve n'aurait pas permis d'atteindre des conditions stables, même s'il était possible d'avoir plus de vieilles forêts et de bois mort que présentement. Nous soutenons qu'il sera très difficile d'appliquer le concept de plage de variabilité naturelle (PVN) en aménagement forestier pour de tels systèmes non équilibrés à Terre-Neuve et dans d'autres régions du Canada. Nous proposons des principes directeurs pour adapter le concept de PVN à partir des connaissances écologiques. Pour adopter une saine approche scientifique, il faut vérifier les hypothèses sur la PVN avec une méthodologie expéri-mentale rigoureuse. Nous suggérons la mise en place d' essais ...
Population‐level estimates of offspring sex ratios in birds typically approximate parity whereas biased ratios within nests are not uncommon. In sexually dimorphic raptors, the costs and relative fitness benefits of rearing male and female progeny vary with changing environmental circumstances. This may lead to substantial deviations from balanced investment in offspring of a particular sex by individual parents. Based on a 13‐year dataset for breeding Merlins Falco columbarius in Saskatoon, Canada, we used a model selection approach to assess the influence of parents, nest‐mates and nesting area on brood sex ratio during the nestling phase. The best model for predicting brood sex ratio included age of the breeding male and brood size for each nest (n = 127); nests with older male breeders and smaller brood sizes had more female young. The population‐level annualized average proportion of male offspring was 0.472 ± 0.017 (mean ± standard error), but tended towards greater production of female young during an initial period of population growth (8 years, 10–21 pairs; proportion male 0.435 ± 0.031) versus a period when the population fluctuated around a presumed carrying capacity (11 years, 24–33 pairs; proportion male 0.500 ± 0.017). Energetics appears to be a finely tuned mechanism driving sex ratio allocation in Merlins at both brood and population levels. Provisioning food for young in the nest represents the male's ability to successfully capture prey, reflecting his age and/or experience, as well as the availability of prey to the male. Confounding this mechanism to determine sex ratio allocation are the pressures created by population dynamics that dictate competition for resources both within the nest (brood size) and external to the nest (population density).
Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) is an important and long-lived tree species found at high elevations in the interior southwest of the United States, but little is known about its regeneration requirements and response to disturbance. We conducted extensive surveys of seedling regeneration and environmental attributes of regeneration sites in undisturbed forest dominated by this species in the Spring Mountains of southern Nevada. Additional surveys tallied new seedling densities and site attributes 4 years after a wildfire in the same area. Seedlings, saplings, and juvenile trees were less abundant than adult trees in the unburned forest, and soils had lower bulk density and greater depth, moisture, and soil organic matter under adult trees than in open areas. Seedling distributions in both unburned and burned forest showed a negative relationship to a heat load index governed by aspect. The density of new seedlings after the fire was negatively related to distance from unburned forest edges. Seedlings were found in clusters and were associated with adult trees (live or dead) in both unburned and burned stands. Seedling emergence from animal-dispersed caches was more frequent in burned habitats than in unburned habitats. These natural regeneration dynamics provide potential guidance for restoration efforts in this ecosystem.
In Nova Scotia, strategic environmental assessments (SEAs) are used to scope the potential impacts of offshore oil and gas activities in the early stages of regulatory decision-making. This study examined stakeholder perceptions and involvement in SEAs for offshore oil and gas decisions on areas being opened by the provincial government for development. Stakeholder comments from 12 SEAs (2003–2019) were evaluated, and 25 interviews with strategic actors involved in the assessments were undertaken and coded. The results reveal actors in Nova Scotia are divided over the effectiveness of a sector-specific SEA: while federal–provincial governments and the regulator were satisfied with SEA function, non-governmental stakeholders questioned the credibility of the regulator as well as the intent and utility of SEAs. Policy recommendations are outlined to remedy gaps in SEA processes, notably implementing integrated management via marine spatial planning in the region.
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