by Audrey Verreault | 17 April 2020
Published in Forests 7(12): 254
This study measured changes in forest composition that have occurred since the preindustrial era along the toposequence of the Gatineau River Valley, Quebec, Canada (5650 km2), based on survey records prior to colonization (1804–1864) and recent forest inventories (1982–2006). Changes in forest cover composition over time were found to be specific to toposequence position. Maple and red oak are now more frequent on upper toposequence positions (+26%, +21%, respectively), whereas yellow birch, eastern hemlock, and American beech declined markedly (-34% to -17%). Poplar is more frequent throughout the landscape, but particularly on mid-toposequence positions (+40%).
In contrast, white pine, frequent on all toposequence positions in the preindustrial forest, is now confined to shallow and coarse-textured soils (-20%). The preindustrial forest types of the study area were mostly dominated by maple, yellow birch, and beech, with strong components of white pine, hemlock, and eastern white cedar, either as dominant or codominant species. In a context of ongoing anthropogenic disturbances and environmental changes, it is probably not possible to restore many of these types, except where targeted silvicultural interventions could increase the presence of certain species. The new forest types observed should be managed to ensure continuity of vital ecosystem services and functions as disturbance regimes evolve.
by Audrey Verreault | 17 April 2020
Published in Journal of Visualized Experiments 117(e54815). doi: 10.3791/54815
Recent soils research has shown that important chemical soil characteristics can change in less than a decade, often the result of broad environmental changes. Repeated sampling to monitor these changes in forest soils is a relatively new practice that is not well documented in the literature and has only recently been broadly embraced by the scientific community. The objective of this protocol is therefore to synthesize the latest information on methods of soil resampling in a format that can be used to design and implement a soil monitoring program. Successful monitoring of forest soils requires that a study unit be defined within an area of forested land that can be characterized with replicate sampling locations. A resampling interval of 5 years is recommended, but if monitoring is done to evaluate a specific environmental driver, the rate of change expected in that driver should be taken into consideration. Here, we show that the sampling of the profile can be done by horizon where boundaries can be clearly identified and horizons are sufficiently thick to remove soil without contamination from horizons above or below. Otherwise, sampling can be done by depth interval. Archiving of sample for future reanalysis is a key step in avoiding analytical bias and providing the opportunity for additional analyses as new questions arise.
by Audrey Verreault | 17 April 2020
Published in Canadian Field-Naturalist 130(2): 133-136
The Eastern Red-backed Salamander (Plethodon cinereus) is well known for its colour polymorphism, which includes 8 colour phenotypes: the red-backed (striped), lead-backed (unstriped), and erythristic morphs, as well as the iridistic, albino, leucistic, amelanistic, and melanistic anomalies. Among these, the prevalence and geographic distribution of rare morphs have received little attention. In this article, we report 2 occurrences of silver-white variants of the red-backed morph of P. cinereus from Québec, Canada. To our knowledge, these variations in stripe colour on the red-backed phenotype represent the first 2 documented mentions for eastern Canada.
by Audrey Verreault | 17 April 2020
Published in Forestry 91(3): 259-270. doi: 10.1093/forestry/cpw059
Long-term success of forest management requires knowledge of standing tree characteristics and, an estimation of their evolution over time. In this study, hardwood stem quality was assessed using a specifically designed, non-destructive quality classification system that comprises four categorical output classes based on stem size and occurrence of external defects. We used data from national forest inventory sample plots distributed across Quebec (Canada) to predict hardwood stem quality and its evolution over time. We used ordinal logistic regression to model multiple stem quality classes. Hardwood stem quality was strongly related to stem harvest priority class and bioclimatic subdomain. Stem quality generally improved with d.b.h. and stand basal area. Changes in hardwood stem quality were strongly related to initial stem quality, with most trees retaining their initial quality over time. Stem quality evolution was also positively related to diameter growth. Overall, both initial and future stem quality were estimated with acceptable precision and minimal bias. Our results suggest that the equations could predict hardwood stem quality distribution and evolution among groups of forest stands.
by Marie-Claude Boileau | 17 April 2020
Published in Forest Science 63(1): 62-70. doi: 10.5849/forsci.15-178
Early successional competition among boreal forest tree and shrub species and its effects on growth of commercial tree species have been a major source of uncertainty in establishing efficient precommercial thinning and brushing prescriptions. We examined the effect of prethinning competitor density, postthinning competitor regrowth density, prethinning stem diameter, and the timing of thinning operations on the growth response of black spruce (Picea mariana [Mill.] BSP) and jack pine (Pinus banksiana Lamb.). In addition, we examined the mortality rate of hardwoods after thinning and the number of new shoots produced per surviving thinned stem. For jack pine, growth response was greatest when thinning occurred between 4 and 9 years after establishment, whereas for black spruce we observed no significant relationship between growth response and the timing of treatment. For jack pine, growth response was significantly affected by pretreatment competitor density, posttreatment competitor regrowth density, and pretreatment stem diameter. For black spruce, no significant relationship was observed between growth response and any variables. Mortality rates and production of new shoots in hardwoods varied significantly between species. Considering the high regrowth potential of willow (Salix spp.) and alder (Alnus spp.), we recommend that stands exhibiting low densities of these species should be left unthinned. Our results help foresters identify stands that require precommercial thinning and call for modification of currently used thinning strategies.
