Like many jurisdictions across North America, the province of Nova Scotia (NS) is faced with the challenge of restoring its forests to a more natural, pre-settlement state through implementation of ecological forestry. At the core of ecological forestry is the idea that natural forest structures and processes may be approximated by designing management practices that emulate natural disturbances. Successful natural disturbance emulation depends on fundamental knowledge of disturbance characteristics, including identification of specific disturbance agents, their spatial extent, severity, and return interval. To date, no comprehensive synthesis of existing data has been undertaken to document the natural disturbance regime of NS forests, limiting the application of natural disturbance emulation . Using over 300 years of documents and available data, we identified the main natural disturbance agents that affect NS forests and characterized their regimes. Overall, fire, wind (predominantly hurricanes), and outbreaks of spruce budworm (SBW) are the most important disturbance agents, causing substantial areas of low (< 30 % mortality), moderate (30-60%), and high (> 60 %) severity disturbance. While characterization of natural historic fire is challenging, due to past human ignitions and suppression, we estimated the mean annual disturbance rate of moderate-to-high severity fire ranged between 0.17-0.4 % yr-1 (250-600 year return interval), depending on ecosystem type. Hurricanes make landfall in NS, on average, every 7 years, resulting in wide-scale (> 500 ha) forest damage. While hurricane track and damage severity vary widely among storms, the return interval of low-to-high severity damage is 700-1,250 years (0.14-0.08 % yr-1). Conversely, the return interval of host-specific SBW outbreaks is much shorter (< 50 years), but more periodic, causing wide-scale, low-to-high severity damage to spruce-fir forests every 30-40 years. Further disturbance agents, such as other insects (e.g., spruce beetle), diseases, ice storms, drought, and mammals can be locally important and/or detrimental to individual tree species, but contribute little to overall disturbance in NS. Climate change is expected to significantly alter the disturbance regime of NS, affecting current disturbances (e.g., increased fire) and driving the introduction of novel agents (e.g., hemlock wooly adelgid), and continued monitoring is needed to understand these changes.
Geographic information systems (GIS) allow researchers to make cost-effective, spatially explicit predictions of species' distributions across broad geographic areas. However, there has been little research on whether using fine-scale habitat data collected in the field could produce more robust models of species' distributions. Here we used radiotelemetry data collected on a declining species, the North American wood turtle (Glyptemys insculpta), to test whether fine-scale habitat variables were better predictors of occurrence than land-cover and topography variables measured in a GIS. Patterns of male and female occurrence were similar in the spring; however, females used a much wider array of landcover types and topographic positions in the summer and early fall, making it difficult for GIS-based models to accurately predict female occurrence at this time of year. Males on the other hand consistently selected flat, low-elevation, riparian areas throughout the year, and this consistency in turn led to the development of a strong GIS-based model. These results demonstrate the importance of taking a more sex-specific and temporally dynamic view of the environmental niche.
PULSIFER, M. D., and HERMAN, T. B. 1989. Comparative arboreal behaviors of wild-caught and captive-born deer mice, Peromyscus maniculatus Wagner, from Isle Haute and mainland Nova Scotia. Can. J. Zool. 67: 789-794. Locomotor, climbing, and nesting behaviors of wild-caught and captive-born deer mice (Peromyscus maniculatus Wagner) from mainland Nova Scotia and from an isolated predator-and competitor-free island were compared in a laboratory observation room. Locomotor activity did not differ consistently between populations, but wall-seeking was significantly greater in mainland mice. When exposed to an artificial tree, insular mice made more climbs than mainland mice, but mainland mice climbed for longer periods. Climbing behavior differed little between males and females in any group. In a choice experiment, mainland mice selected elevated nest sites significantly more often than ground-level nest sites, while insular mice exhibited no preference. PULSIFER, M. D., et HERMAN, T. B. 1989. Comparative arboreal behaviors of wild-caught and captive-born deer mice, Peromyscus maniculatus Wagner, from Isle Haute and mainland Nova Scotia. Can. J. Zool. 67 : 789 -794. Les comportements de locomotion, d'escalade et de nidation ont Ct C cornparks en laboratoire, dans une enceinte, c h~z des Souris sylvestres (Peromyscus maniculatus Wagner) nCes en captivitC et des souris capturCes en nature en Nouvelle-Ecosse et sur une ile isolCe, sans prCdateurs et sans compktiteurs.L'activitC locomotrice ne diffkrait pas de fa~on constante chez les populations, mais la recherche des parois s'est avCrCe significativement plus frCquente chez les souris du continent. En prCsence d'un arbre artificiel, les souris insulaires grimpaient plus souvent que les souris du continent, mais celles-ci restaient grimpCes plus longtemps. Le comportement d'escalade diffkrait peu chez les miles et les femelles de tous les groupes. Dans une expCrience h choix multiples, les souris du continent choisissaient des sites de nidation ClevCs significativement plus souvent que les sites au sol, alors que les souris insulaires n'ont pas manifest6 de prCfCrence.[Traduit par la revue]
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