Following the appointment of the new Cabinet, the Forest Sector now reports to the ministère des Ressources naturelles et des Forêts, while the Wildlife and Parks Sectors report to the ministère de l'Environnement, de la Lutte aux changements climatiques, de la Faune et des Parcs. Adjustments will be made to the website over time.

Comparison of growth and physiology of layers and naturally established seedlings of black spruce in a boreal cutover in Québec

by | 2 June 2020

Published in Canadian Journal of Forest Research 29: 1-8

Growth and physiology of layers versus naturally established seedlings of boreal black spruce (Picea mariana (Mill.) BSP) were compared 15 years after a cutover in Québec. During the first 8 years, height growth of seedlings was greater than that of layers, averaging 10.4 and 7.0 cm/year, respectively. For the last 5 years, annual height growth of layers and seedlings did not differ (25 cm/year; p > 0.05). Over the entire 15-year period, total height growth of seedlings (251 cm) was greater than that of layers (220 cm), although total height did not differ (p > 0.05)  over the last 6 years. During the 15th growing season, there were no differences (p > 0.05) for predawn shoot water potential, stomatal conductance, net photosynthesis, intercellular to ambient CO2 ratio, water use efficiency, and hydraulic conductance between layers and seedlings. For diurnal shoot water potential, seedlings showed slightly less stress than layers on two of the four sampling dates. Thus, in the first few years following the cutover, the slower growth observed for layers indicated that they had a longer acclimation period following the cutover. Afterwards, similar height growth, total height, and physiological characteristics of the two regeneration types indicated that layers can perform as well as naturally established seedlings.

Diapause induction and overwintering stage in the fir coneworm (Lepidoptera: Pyralidae)

by | 2 June 2020

Published in The Canadian Entomologist 131: 779-786

A laboratory experiment was conducted to identify the overwintering stage of the fir coneworm, Dioryctria abietivorella (Grote), in eastern Canada and determine the influence of photoperiod on diapause induction. ln another experiment, different developmental stages were exposed to field conditions to evaluate their capacity to survive the overwintering period. lnsects were either placed in the duff or exposed to ambient (above ground) conditions to assess the importance of overwintering site on winter survival. Exposure of the fir coneworm to constant short-days or a daily decreasing photoperiod during larval development induced almost all insects to initiate diapause at the fifth instar. Third-, fourth-, and fifth-instar larvae survived the overwintering period when placed in the duff. Because the fir coneworm must leave its host tree and drop to the ground to avoid rigorous winter conditions, we concluded that only fifth-instar larvae couId resume development in spring using such a strategy.

Performance of the fir coneworm Dioryctria abietivorella (Grote) as affected by host species and presence or absence of seed cones

by | 2 June 2020

Published in Agricultural and Forest Entomology 1: 189-194

1) Larval performance of Dioryctria abietivorella (Grote) (Lepidoptera: Pyralidae) was compared when insects were reared in white spruce, black spruce and Jack pine seed orchards. For each species, half of the insects developed in the presence of cones, while the other half was maintained on branches without cones.

2) Significantly faster development rates were observed on spruce species when compared to Jack pine. Significant differences in survival were also recorded between the different feeding treatments.

3) The presence of seed cones on spruce species significantly increased insect mean weight compared with branches without cones, but no significant differences were noticed between the different tree species with cones.

4) White spruce is the most suitable host tree for fir coneworm feeding and the availability of seed cones plays an important role in determining D. abietivorella larval performance.

Effect of the relative abundance of conifers versus hardwoods on soil d13C enrichment with soil depth in eastern canadian forests

by | 2 June 2020

Published in Ecosystems 18: 629-642

Soils are a major component of the global C cycle, and considerable effort has been dedicated to improve our understanding of factors controlling soil organic C (SOC) turnover and stabilization in the last decades. Carbon stable isotopes are useful in this respect as they represent an integrative indicator of SOC biogeochemical processing. In the present study, C concentration and d13C were measured in soil horizons of 21 forest sites located at the transition zone between the hardwood and the conifer forest in Québec, Canada, and related to 13 biophysical variables to identify the main drivers of SOC storage and turnover. Carbon concentrations in the forest floor (FF) and the B- and C-horizons were, respectively, strongly correlated with percentage of clay (Pclay), the mean annual precipitation: potential evapotranspiration ratio (MAP:PET), and percentage of hardwoods (Phwd). In FF, d13C was poorly correlated with the studied variables, whereas in mineral horizons, it was significantly correlated with mean annual air temperature (MAAT) and the percentage of conifers (Pc) and Pclay. Across the studied area, d13C increased on average by 2.00/00 from the FF to the C-horizon. The isotopic enrichment with soil depth (b) was strongly negatively correlated with Pc, which explained 55% of its variability among sites. This suggests that the vegetation type is an important driver of soil C long-term turnover rate in forest ecosystems. Overall, our data suggest that hardwood forest expansion in response to climate change might reduce the stability and the storage of SOC in the future.