by Claire Morin | 25 August 2020
Published in Forest Ecology and Management 281: 130-139
Dolomitic lime (CaMg(CO3)2) was applied in 1994 at rates of 0–50 Mg ha-1 to sugar maples (SMs) (Acer saccharum Marsh.) in a base-poor and declining northern hardwood stand subjected to a high level of acid deposition in Québec. The soil chemistry and the SM nutrition, growth, crown vigor, and regeneration status were evaluated 15 years after treatment. The soil chemical properties still responded strongly to lime after 15 years. Similarly, the foliar Ca and Mg concentrations were still higher for treated trees relative to the control trees. After 15 years, the mean crown dieback of trees decreased quadratically with the lime rate, from 39% for the control trees to a value of 1–3% for the lime rates of 5 Mg ha-1 and higher. Additionally, the stem basal area increment for the limed trees was nearly double that of the unlimed trees in 2009. The lime application was also beneficial to the SM regeneration. The overall SM seedling density increased with the lime rate, being nearly twice as much in the 50 Mg ha-1 (32 seedlings m-2) compared with the controls (16 seedlings m-2). The proportion of the SM seedlings to all of the other species increased quadratically from 22% in controls to more than 55% in the 5–50 Mg ha-1 treatments. In contrast, the proportion of competitive species decreased quadratically with the lime rate, including American beech (Fagus grandifolia Ehrh.) for which the proportion in the treated plots (24%) was nearly half the proportion observed in the controls (46%). However, increase in stem density of regeneration and canopy closure in response to lime application limit the development of the regeneration which did not benefit in terms of diameter and height. These results show that a single lime addition has long-term beneficial effects on the soil chemistry and the SM nutrition, vigor, growth, and regeneration in base-poor and declining northern hardwood stands. Moreover, the results confirm that liming is an essential tool to restore the SM representation and health in acidic and base-poor soils.
by Marie-Claude Boileau | 31 July 2020
This scientific advice is an update on the knowledge and status of the American eel in Québec. Once considered one of the most common fish species in the province, its distribution range and abundance are showing the greatest decline ever observed. Despite recovery efforts over the past two decades, species recruitment is still declining and the stock shows no signs of recovery. There are multiple causes to this decline, many of them anthropogenic. The general decline in the species’ range is such that some states, provinces and agencies have granted the American eel a conservation status to ensure its protection and others are in the process of doing so. The abundance of the eel stock in Québec is regarded as very concerning.
by Audrey Verreault | 29 July 2020
Published in Pulp and Paper Research Institute of Canada 107(16): 1-32
This report presents data from 125 black spruce stands located in the Boreal forest of Canada from Newfoundland to western Ontario. A description of the vegetation is presented by strata and in total.
Two major vegetation regions were found: the Atlantic located to the east, and the Continental, located to the west of the 65th meridian. Site fertility was lower in the Atlantic region than in the Continental region. The diversity of the vascular species increased from east to west, with a maximum found to the north of the Great Lakes. The highest number of species was found on the most fertile of the mesic to hydric sites. The herb stratum contributed most to the total number of observed species. For the sake of comparison the stands were also described according to currently used site types.
To explore the possibility of using the dominance of vegetation as a continuous variable in relation to site fertility, certain species and species groups were selected for intensive study. By grouping appropriate species, a closer correlation with site index was obtained than by considering the species individually. For site index prediction, the multiple regression equations for these groups were developed which would minimize prediction errors, and would consist of variables which would be easy to identify and be suitable for air photo interpretation or direct ground measurement. Both multiple regression equations and currently used site types appear to be applicable throughout the study area. However, site index prediction was better with regression equations than with site types. This is due, in part, to the wide range of fertility found within a given site type.
by Marie-Claude Boileau | 29 July 2020
Published in Canadian Journal of Forest Research 6(3): 357-367
Dry matter production data were obtained for jack pine (Pinus banksiana Lamb.) stands growing at three density levels on two sites. Regression equations relating tree weight to diameter and height were calculated for stem wood, stem bark, branches, needles, cones, and total aboveground biomass, as well as for periodic net annual increment of these components. Different sets of equations were needed to evaluate biomass on each site, but density levels within sites could be grouped. Total net periodic annual weight increment was linearly related to foliage weight and basal area, but a levelling-off at higher densities was evident when basal area was replaced by stand density index or bole area equivalent as the measure of density.
by Audrey Verreault | 29 July 2020
Published in Annals of the Entomological Society of America 78: 14-19
ln laboratory studies larval development and total mortality of Agromyza frontella on hop medic, Medicago lupulina, were similar to previously reported values on alfalfa, M. sativa. However, pupal development was longer and both pupal weight and total fecundity were somewhat lower than for alfalfa-reared individuals. Nevertheless hop medic is a suitable alternate host and, given its widespread occurrence throughout northeastern North America, could play a role in the dynamics of established and expanding populations of A. frontella, particularly when alfalfa is unavailable.
