by Claire Morin | 30 January 2019
Published in Annals of Forest Science https://doi.org/10.1007/s13595-011-0112-0
Introduction. Deterministic single-tree models are commonly used in forestry. However, there is evidence that stochastic events may interact with the nonlinear mechanisms that underlie forest growth. As a consequence, stochastic and deterministic simulations could yield different results for the same single-tree model and the same initial conditions. This hypothesis was tested in this study.
Material and methods. We used a single-tree growth model that can be implemented either stochastically or deterministically. Two data sets of 186 and 342 plots each were used for the comparisons. For each plot, the simulations were run on a 100-year period using 10-year growth steps. Three different response variables were compared.
Results. The results showed that there were differences between the predictions from stochastic and deterministic simulations for some response variables and that randomness alone could not explain these differences. In the case of deterministic simulations, the fact that predictions are reinserted into the model at each growth step is a concern. These predictions are actually random variables and their transformations may result in biased quantities. Forest growth modellers should be aware that deterministic simulations may not correspond to the mathematical expectation of the natural dynamics.
by Claire Morin | 30 January 2019
Published in The Canadian Field-Naturalist 125(1): 58-60. https://doi.org/10.22621/cfn.v125i1.1126
Three colour morphs of the Eastern Red-backed Salamander, Plethodon cinereus, are known in eastern Canada: red-backed, lead-backed, and erythristic. Anomalies, including two albino and four leucistic individuals, are also known from eastern Canada. We report the first salamander individuals exhibiting amelanism, which is a lack of black skin pigment, but with black eyes, one from Quebec and one from Nova Scotia, Canada.
by Marie-Claude Boileau | 30 January 2019
Published in Canadian Journal of Forest Research 41: 873-880
Northern hardwoods have undergone a marked change in their dynamics, with American beech (Fagus grandifolia Ehrh.) increasing in abundance relative to sugar maple (Acer saccharum Marsh.). This study aims to better understand this sudden shift in recruitment dynamics. We performed an extensive analysis of the age structure, radial growth pattern, and release history on >700 saplings from 34 mature maple–beech stands of southern Quebec. We found (i) that the sapling age structures showed a progressive decrease in the establishment of maple relative to beech starting about 40 years ago, (ii) a change in the species growth hierarchy that started in the 1980s due to increasing radial growth of beech, (iii) that this growth trend is negligible for both maple and beech when we account for size and suppression status, and finally (iv) that the growth trend appears to be independent of present soil conditions. These results contrast with previous studies conducted at the adult stage that reported a growth decline for maple. We conclude that this change in recruitment dynamics is not related to growth, and consequently, further studies investigating this phenomenon should concentrate on establishment and survival.
by Claire Morin | 30 January 2019
Published in Canadian Journal of Forest Research 41: 1308-1318
Family genetic variability of the rooting characteristics of white spruce (Picea glauca [Moench] Voss.) cuttings harvested from 3-year-old stock plants was evaluated for 75 half-sib families. Growth, root system architecture, and gas exchange of the cuttings during the rooting phase (B+0) and the two subsequent growing seasons (B+1 and B+2) were evaluated. The root initiation phase (B+0) and the root development phases (B+1 and B+2), were found to be under strong genetic control. The weak correlations found between B+0 and the B+1 and B+2 phases may indicate that gene expression during B+0 is not related to root growth and development during B+1 and B+2. Strong positive correlations were observed between plant root and aboveground characteristics at the end of the B+1 and B+2 phases. This suggests that an indirect and efficient selection for white spruce families producing cuttings with heavier root dry masses could be based on the measures of aboveground morphological characteristics. Finally, the strong genetic control of morphological characteristics found in this study indicates that the selection of superior genotypes at a clonal level is possible for intensive forest management.
by Marie-Claude Boileau | 30 January 2019
This document addresses the concerns of the people of Québec and provides a concrete example of Québec’s achievements in the sustainable management of the boreal forest. It describes the actions and measures already taken, as well as those that remain to be carried out to ensure the sustainable management of the boreal forest in Québec.
