Academic literature on the topic 'Laurentian Mountains (Québec) in art'

AbstractIn 2012, an unexpected outbreak of Lambdina fiscellaria (Guenée) (Lepidoptera: Geometridae) occurred in the Laurentian Mountains, Québec, Canada, known for its harsh climate. We wondered whether the eggs were sufficiently cold hardy to survive there and, if so, how long this outbreak would last. Therefore, we assessed the capacity of the eggs to supercool, to tolerate short exposures to low sub-zero temperatures, or to successfully overwinter in the field. The same assays were performed with eggs from the island of Newfoundland, Newfoundland and Labrador, Canada. The mean supercooling point of eggs from the two populations increased from −40.2 °C in mid-February to −33.7 °C in mid-May. These eggs may also die at sub-zero temperatures above their supercooling point, depending on exposure durations. In the fall of 2012 when eggs were put out in the field, < 10% survived in the Laurentian Mountains, whereas > 70% survived further south. In the spring of 2013, no parasitism was detected in the population. However, the two cold waves that swept across the Laurentian Mountains the preceding winter were likely responsible for the collapse of the population. This study demonstrates that L. fiscellaria eggs may succumb to sub-zero temperatures above their supercooling point under field conditions.

This study was undertaken to determine the contribution of old-growth and senescent forest stands regenerated through clear-cutting to the biodiversity of wet boreal fir stands in eastern Quebec because overmature stands are becoming scarce in that region. The study area was located in the Laurentian Mountains north of the city of Québec. The structure and composition of nonvascular plant communities (mosses, hepatica, lichens, and saprophytic fungi) of old-growth forests were compared with those of mature or senescent fir stands harvested 60 years ago. Nonvascular plants have a more uniform structure and a lower diversity in mature than in senescent or old-growth forests. A variety of specialized soil- and wood-inhabiting species and many rare species not observed in mature stands regenerated through clear-cutting are found in the latter. Structural diversity of senescent second-growth fir stands becomes similar to that of old-growth stand because of mortality within the overstory. These structural characteristics favour the development of diversified nonvascular plant communities, especially wood-inhabiting species found on slightly decomposed woody debris and soil-inhabiting species that colonize disturbed soils.[Journal translation]

Forest clearance can affect the levels of dissolved organic carbon (DOC), nutrient concentrations and algal biomass in streams, but the possible effect of these inputs on downstream lakes is usually surmised rather than demonstrated. To evaluate the effect of forest clearance on DOC and nutrient cycling in lakes, DOC, total phosphorus (TP), total nitrogen (TN) and chlorophyll (chl a) concentrations were measured in 47 Canadian Shield lakes in Quebec. Of these lakes, 25 were located in drainage basins that were partially clear-cut one to four years previously. In the disturbed sites, an uncut 20-m bufferstrip was left around the lakes and permanent water courses.
To account for differences among the watersheds that are not related to forest harvesting, I also collected a series of catchment and morphometric variables (watershed area, lake area, drainage ratio, forest, wetland, and upstream lake area, watershed slope, water residence time and lake depth). Lake characteristics in undisturbed and disturbed watersheds were compared to determine if forest clearance has a detectable effect on the water quality of downstream lakes. Although comparisons of seasonal and monthly means of the water quality variables between disturbed and reference sites were inconclusive, likely because of high natural variability, the size of the clear-cut was significantly related to means of the water quality characteristics. DOC, TP, TN and chl a increased in lake water with the area of the clear-cuts when large portions of the watershed ($>$50%) were cleared. The results of this study suggest that logging has an effect on water quality and even though a bufferstrip of twenty meters reduces this effect largely, it may not be enough to provide complete protection against the effects of logging activities.

The $ sp3$H thymidine incorporation (TTI) method has been frequently used to estimate benthic bacterial production rates in well oxygenated marine and river sediments, but not in the frequently more reduced lake sediments. In chapter 1, I evaluate the published sediment production literature and examine useful predictors of in situ bacterial production in mostly marine and riverine sediments. In chapters 2 and 3, I estimated and compared benthic production rates by TTI, frequency of dividing cells (FDC), the dilution method (DIL) and sediment respiration (SR) in 13 Quebec lakes to assess the reliability of the TTI based production rates. The TTI method was first calibrated, but despite keeping incubation times short and at in situ temperature, using optimal sediment volumes to saturate $ sp3$H thymidine (TdR) uptake rates, and correcting production rates for $ sp3$H-DNA recovery efficiencies, only a maximum of 10% of $ sp3$H TdR was incorporated into DNA and only extracellular isotope dilution could be accounted for (chapter 2). Most problematic, however, is the increasing presence of active bacteria unable to take up and incorporate TdR as lake sediments become more reduced (chapter 3). TTI based results are also not nearly as well correlated to environmental factors as those obtained from SR. (Abstract shortened by UMI.)

Eight fertilization treatments were applied in May 1987 to two sugar maple stands. This was followed by soil and foliar sampling and decline evaluation in mid-summer 1987 and foliar sampling and decline evaluation in mid-summer 1988.
Trees selected for sampling purposes on average showed evidence of light to moderate decline. Foliar nutrient status was found to be poor at both sites, with Ca, Mg, K and P at or very near to deficiency levels although foliar molar ratios for Ca/K, Ca/Mg and Ca/Al were well within their respective critical ranges.
Fertilization had significant effects on several elemental concentrations of the soil and foliage at the Entrelacs sites. Effects in general showed an increase in base cation concentrations when those elements were supplied in high enough quantities in the fertilizers. Fertilization had no significant effect on decline levels.
Positive correlations were obtained between soil B horizon levels and foliar Ca, Mg and K and between soil FH horizon levels and foliar K and Al.