Recent publications

Influence of afforestation on soil: The case of mineral weathering.

Wed, 10 Apr 2013 12:27:15 MST

Although concerns have been raised that increased nutrient demand by fast growing tree species could deplete soil nutrient pools, recent research suggests that some species are able to obtain nutrients via soil mineral weathering. Hybrid poplars, which are fast growing and nutrient demanding species, are increasingly used in intensive silvicultural settings. Understanding whether hybrid poplars have an effect on long term nutrient availability and can promote soil mineral weathering is therefore important. We investigated the levels of base cations (i.e. K, Ca, Mg, and Na) of surface soils (0–20 cm) in 13 hybrid poplar plantations in Quebec, and compared the results with those of adjacent abandoned agricultural fields. To evaluate whether exchangeable base cation pools and non-exchangeable pools (i.e. those in the crystal lattice of minerals) were being depleted, we used a sequential leach with diluted salt (BaCl₂ for exchangeable) and weak acid solutions (HCl and HNO₃ for non-exchangeable). Levels of exchangeable and non-exchangeable cations were not statistically different between land use types. Exploratory analyses, however, revealed trends toward a greater depletion of Ca, Mg and Na in non-exchangeable forms following afforestation. The depletion of these non-exchangeable base cations due to afforestation occurred at sites where greater levels were initially present in soil. The results suggest increased soil mineral weathering due to greater amounts of minerals susceptible to dissolution and, in part, high clay content. Based on Ca, Mg and K concentrations of the different leaches and their molar ratios (Ca/ΣAl + Fe, Mg/ΣAl + Fe and K/ΣAl + Fe), we propose a lesser role of soil mineral weathering on Ca cycling than Mg and K, which could lead to faster depletion of exchangeable Ca pools of the surface soil due to fast growth and high Ca demand by the poplars.

Characterization of knots in plantation white spruce

Fri, 05 Apr 2013 06:42:10 MST

Knot size and distribution are of key importance to wood quality and lumber grade yield. This study characterized white spruce (Picea glauca [Moench] Voss) knots with computerized tomography images and knot mapping software. The characteristics included shape, number, diameter, inclination (angle between z-axis and the line connecting the knot’s starting point at the pith with the end point), azimuth direction, and distribution inside the stem. There were on average 112 grade-important knots per tree in a 32-yr-old plantation white spruce tree, 7% of which could downgrade lumber from Select Structural to No. 2 and lower grades. A total of 3.6% were ramicorn knots, and 70% had an inclination angle between 60 and 80° with the tree axis. There were 24 more knots per tree with every 2-cm increase in tree diameter. Knot diameters had a positively skewed frequency distribution with an average of 156 mm. The majority of the knots had a taper between 0.18 and 0.38 mm/mm, which could have had a major impact on lumber mechanical properties. Knots grew steeply upward until reaching their greatest diameters and became more horizontal afterward. Butt logs had smaller but a higher number of knots and a lower percentage of knot volume (out of log volume) than those higher up. In the same height growth unit, inclination angle decreased with increasing height. Wider knots had a smaller inclination angle.White spruce has a weak self-pruning mechanism and is prone to forking or ramicorn branching. The widest knot in a height growth unit is more likely to be found in the south direction. Trees from wider spacing tend to have wider knots but not necessarily a higher number of knots at the same heights. The results suggest the need for pruning operations and including knot information in determining sawing strategies. Information from this study should be useful in forest management decision-making and improving wood use.

Global wildland fire season severity in the 21st century.

Thu, 04 Apr 2013 07:50:31 MST

We used Cumulative Severity Rating (CSR), a weather-based fire danger metric, to examine the potential influence of climate change on global fire season severity. The potential influence of climate change on fire season length was also addressed. We used three General Circulation Models (GCMs) and three emission scenarios to calculate the CSR and fire season length for mid-century (2041–2050) and late century (2091–2100) relative to the 1971–2000 baseline. Our results suggest significant increases in the CSR for all models and scenarios. Increases were greatest (more than three times greater than the baseline CSR) for the Northern Hemisphere at the end of the century. Fire season length changes were also most pronounced at the end of the century and for northern high latitudes where fire season lengths will increase by more than 20 days per year. The implications from this study are that fire seasons will be more severe in future and that conventional fire management approaches may no longer be effective.

Measuring environmental change in forest ecosystems by repeated soil sampling: a North American perspective.

Thu, 04 Apr 2013 06:59:26 MST

Environmental change is monitored in North America through repeated measurements of weather, stream and river flow, air and water quality, and most recently, soil properties. Some skepticism remains, however, about whether repeated soil sampling can effectively distinguish between temporal and spatial variability, and efforts to document soil change in forest ecosystems through repeated measurements are largely nascent and uncoordinated. In eastern North America, repeated soil sampling has begun to provide valuable information on environmental problems such as air pollution. This review synthesizes the current state of the science to further the development and use of soil resampling as an integral method for recording and understanding environmental change in forested settings. The origins of soil resampling reach back to the 19th century in England and Russia. The concepts and methodologies involved in forest soil resampling are reviewed and evaluated through a discussion of how temporal and spatial variability can be addressed with a variety of sampling approaches. Key resampling studies demonstrate the type of results that can be obtained through differing approaches. Ongoing, large-scale issues such as recovery from acidification, long-term N deposition, C sequestration, effects of climate change, impacts from invasive species, and the increasing intensification of soil management all warrant the use of soil resampling as an essential tool for environmental monitoring and assessment. Furthermore, with better awareness of the value of soil resampling, studies can be designed with a long-term perspective so that information can be efficiently obtained well into the future to address problems that have not yet surfaced.

Research at the Laurentian Forestry Centre of Natural Resources Canada – Exotic forest pests.

Tue, 02 Apr 2013 14:19:24 MST

By definition, exotic forest pests are diseases or insects that are present outside of their natural range. They are described as "invasive" when they alter the ecosystems into which they are introduced. According to Canadian Forest Service (CFS) researchers, more than 80 exotic pests harmful to Canada's forests have become established here since 1882. This brochure describes the main exotic pests that are currently being studied at the Canadian Forest Service's Laurentian Forestry Centre (LFC).

La recherche au Centre de foresterie des Laurentides de Ressources naturelles Canada – Les ravageurs forestiers exotiques.

Tue, 02 Apr 2013 14:14:10 MST

Programme forestier des Premières Nations. Rapport annuel 2009-2011 et survol des 15 ans d'existence du Programme.

Thu, 28 Mar 2013 13:13:39 MST

The First Nations Forestry Program (FNFP) was the Govenment of Canada's principal capacity-building approach for First Nations forestry from 1996 to 2011. The program was jointly funded by Natural Resources Canada and Aboriginal Affairs and Northern Development Canada. The FNFP supported research, outreach activities and capacity-building partnership projects to enhance the ability of First Nations to manage forest resources and participate in economic opportunities both on- and off-reserve.