Unravelling the past to manage Newfoundland’s forests for the future

Abstract

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 ...

Assessment of Rusty Blackbird Habitat Occupancy in the Long Range Mountains of Newfoundland, Canada Using Forest Inventory Data

“…Overall, landcover within our survey point buffers consisted of an average of 3% lakes, 7% bog, 29% coniferous scrub, and 48% balsam fir-and/or black spruce-dominated forest. Natural disturbances such as wildfire and outbreaks of defoliating insects are uncommon at higher elevations due to climatic conditions, leading to the development of mixed age, old growth fir forests having an abundance of canopy gaps and complex vertical structure [48,50]. Trees at this site have been aged at over 250 years old [48], and around our survey points alone, 27% of points contained 50% or more forest greater than 110 years old.…”

Saltmarsh archives of vegetation and land use change from Big River Marsh, SW Newfoundland, Canada

“…Fluctuations in tree pollen values could also be associated with phases of hemlock looper outbreak. Arsenault et al (2016) cite defoliating insects as the cause of the largest disturbance footprints in Newfoundland. Outbreaks are thought to occur approximately every 10-12 years in Newfoundland (Iqbal et al 2011).…”

Extending Estimates of Tree and Tree Species Presence-Absence through Space and Time Using Landsat Composites

“…The estimated increase in treed area over the 25year time period from 1985-2010 may be explained as a consequence of the disturbance history of the region. The island portion of Newfoundland experienced the largest spruce budworm outbreak on record during 1972-1992, and 1986 was a major fire year (Arsenault et al 2016). Many areas affected by these disturbances experienced regeneration during 1985-2010, which likely contributed to the gradual increase in the overall treed area.…”