Black Spruce Trees Research Articles

Black spruce trees from fire-origin stands have higher wood mechanical properties than those from older, irregular stands

In the eastern Canadian boreal forest, long fire return intervals lead to over 60% of stands having an irregular, uneven-aged structure, which is associated with slower growth. The aim of this study was to examine the effect of stand structure on the clear wood mechanical properties of black spruce (Picea mariana (Mill.) B.S.P.). A total of 128 trees were destructively sampled from stands of regular and irregular structure across Quebec, Canada. Nonlinear mixed-effects models were developed for each stand type to describe the variation in modulus of elasticity (MOE) and modulus of rupture (MOR) in small defect-free samples as functions of cambial age and annual ring width. Mechanical properties were strongly related to cambial age, with a smaller influence of ring width. After accounting for these variables, both MOE and MOR were higher in samples from stands of regular structure, although differences were less pronounced in the upper stem compared with breast height. The fixed effects of the models explained between 34% and 53% of the variation in mechanical properties. A higher incidence of mild compression wood in trees of layer origin may explain the observed differences between stand structures.

Unusual forest growth decline in boreal North America covaries with the retreat of Arctic sea ice

The 20th century was a pivotal period at high northern latitudes as it marked the onset of rapid climatic warming brought on by major anthropogenic changes in global atmospheric composition. In parallel, Arctic sea ice extent has been decreasing over the period of available satellite data records. Here, we document how these changes influenced vegetation productivity in adjacent eastern boreal North America. To do this, we used normalized difference vegetation index (NDVI) data, model simulations of net primary productivity (NPP) and tree-ring width measurements covering the last 300years. Climatic and proxy-climatic data sets were used to explore the relationships between vegetation productivity and Arctic sea ice concentration and extent, and temperatures. Results indicate that an unusually large number of black spruce (Picea mariana) trees entered into a period of growth decline during the late-20th century (62% of sampled trees; n=724 cross sections of age >70years). This finding is coherent with evidence encoded in NDVI and simulated NPP data. Analyses of climatic and vegetation productivity relationships indicate that the influence of recent climatic changes in the studied forests has been via the enhanced moisture stress (i.e. greater water demands) and autotrophic respiration amplified by the declining sea ice concentration in Hudson Bay and Hudson Strait. The recent decline strongly contrasts with other growth reduction events that occurred during the 19th century, which were associated with cooling and high sea ice severity. The recent decline of vegetation productivity is the first one to occur under circumstances related to excess heat in a 300-year period, and further culminates with an intensifying wildfire regime in the region. Our results concur with observations from other forest ecosystems about intensifying temperature-driven drought stress and tree mortality with ongoing climatic changes.

Assessment of xylem phenology: a first attempt to verify its accuracy and precision

This manuscript aims to evaluate the precision and accuracy of current methodology for estimating xylem phenology and tracheid production in trees. Through a simple approach, sampling at two positions on the stem of co-dominant black spruce trees in two sites of the boreal forest of Quebec, we were able to quantify variability among sites, between trees and within a tree for different variables. We demonstrated that current methodology is accurate for the estimation of the onset of xylogenesis, while the accuracy for the evaluation of the ending of xylogenesis may be improved by sampling at multiple positions on the stem. The pattern of variability in different phenological variables and cell production allowed us to advance a novel hypothesis on the shift in the importance of various drivers of xylogenesis, from factors mainly varying at the level of site (e.g., climate) at the beginning of the growing season to factors varying at the level of individual trees (e.g., possibly genetic variability) at the end of the growing season.

Dynamics of active layer in wooded palsas of northern Quebec

Palsas are organic or mineral soil mounds having a permafrost core. Palsas are widespread in the circumpolar discontinuous permafrost zone. The annual dynamics and evolution of the active layer, which is the uppermost layer over the permafrost table and subjected to the annual freeze–thaw cycle, are influenced by organic layer thickness, snow depth, vegetation type, topography and exposure. This study examines the influence of vegetation types, with an emphasis on forest cover, on active layer dynamics of palsas in the Boniface River watershed (57°45′ N, 76°00′ W). In this area, palsas are often colonized by black spruce trees (Picea mariana (Mill.) B.S.P.). Thaw depth and active layer thickness were monitored on 11 wooded or non-wooded mineral and organic palsas in 2009, 2010 and 2011. Snow depth, organic layer thickness, and vegetation types were assessed. The mapping of a palsa covered by various vegetation types and a large range of organic layer thickness were used to identify the factors influencing the spatial patterns of thaw depth and active layer. The active layer was thinner and the thaw rate slower in wooded palsas, whereas it was the opposite in more exposed sites such as forest openings, shrubs and bare ground. Thicker organic layers were associated with thinner active layers and slower thaw rates. Snow depth was not an important factor influencing active layer dynamics. The topography of the mapped palsa was uneven, and the environmental factors such as organic layer, snow depth, and vegetation types were heterogeneously distributed. These factors explain a part of the spatial variation of the active layer. Over the 3-year long study, the area of one studied palsa decreased by 70%. In a context of widespread permafrost decay, increasing our understanding of factors that influence the dynamics of wooded and non-wooded palsas and understanding of the role of vegetation cover will help to define the response of discontinuous permafrost landforms to changing climatic conditions.

Stem biomass, C and N partitioning and growth efficiency of mature pedigreed black spruce on both a wet and a dry site

Worldwide, efforts to manage atmospheric CO2 are being explored both by reducing emissions and by sequestering more carbon (C). Stem biomass, C, and nitrogen (N) parameters were measured in plots of first-generation (F1), 32-year-old black spruce (Picea mariana (Mill.) B.S.P.) from four full-sib families studied previously for drought tolerance and differential productivity on both a dry and a wet site in central Ontario, Canada. The wet site had greater stem wood N and bark N concentrations than the dry site. Site differences in N were most likely driven by soil moisture stress impairing N uptake, as soil N was equal at both sites. Drought-tolerant (faster growing) families had lower wood density than drought-intolerant families on the wet site but there were no wood density differences between families on the dry site. Allometric analysis showed greater total stem dry mass per unit total belowground dry mass for drought-tolerant than intolerant families and for wet than dry sites, indicating a differential allocation of photosynthate dependent on both genotype and environment. Allometric analysis also showed greater total stem dry mass per unit total needle dry mass (growth efficiency) for drought-tolerant than intolerant families and for the wet than the dry site. This indicates greater productivity is a result of greater growth efficiency caused by greater net photosynthesis (shown previously) and greater partitioning of biomass to stem relative to total roots. The variation in physiological processes documented in our previous investigations and the biomass allocation variation shown here most probably underlie the increase in stem productivity from both black spruce tree improvement programs and increased water availability.

Nest-site selection, nest survival, productivity, and survival of Spruce Grouse in Wisconsin

Abstract Spruce Grouse (Falcipennis canadensis) are listed as threatened in Wisconsin, and the boreal habitats in which they occur are likely to be threatened by changing climatic conditions. However, the limited information available on Spruce Grouse in the Upper Great Lakes region makes it unclear which habitat features are important for Spruce Grouse nesting in Wisconsin. We radiotracked 30 female Spruce Grouse in northern Wisconsin from 2007–2012 and located 25 nests. Eighteen of 25 nests were beneath black spruce (Picea mariana) trees. Only three nests were in upland, and only one in a stand of jack pines (Pinus banksiana), in contrast to studies from Michigan and Ontario. Overall concealment was a good predictor of nest sites for Spruce Grouse, but not a good predictor of nest survival. Nest survival was associated with moderately dense and uniform 0–0.5 m lateral vegetation cover. Seventeen of 25 nests were successful, with a daily survival rate of 0.985, overall productivity of 1.0 young/female, a...

Validation of L-Architect model for balsam fir and black spruce trees with structural measurements

The fine reconstruction of tree structure provides important information that is relevant to forest ecological processes and may be linked to wood quality attributes. Terrestrial laser scanners (TLS) provide detailed and accurate 3-D data and have the potential to enhance forest inventories with fine-scale information on structure. However, in forests, TLS data are limited by the effects of object occlusion and wind. Therefore, adequate tree reconstruction is not possible. In previous studies, we used the architectural model L-Architect (LiDAR data to tree Architecture) to overcome the limitations of TLS to characterize the 3-D tree structure. In this study, L-Architect was validated using structural measurements for two coniferous species found in Newfoundland (Canada), namely, balsam fir (Abies balsamea) and black spruce (Picea mariana). The model reproduced realistic tree structures using TLS data and allometric relationships to define the total amount of foliage following two main steps: branch growth and addition of foliage within the crown. Results from L-Architect were compared with measurements of branching structure from the main stem (angle of insertion, length, and diameter) and vertical distribution of foliage indicated by the shoot vertical distribution for six sampled trees. Averaged normalized root-mean square errors of 21%, 20%, 25%, and 21% were obtained for branch diameter, branch length, angle of branch insertion, and vertical distribution of foliage, respectively.

Age and size effects on seed productivity of northern black spruce

Slow-growing conifers of the northern boreal forest may require several decades to reach reproductive maturity, making them vulnerable to increases in disturbance frequency. Here, we examine the relationship between stand age and seed productivity of black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) in Yukon Territory and Alaska. Black spruce trees were aged and surveyed for cone production and seed viability across 30 even-aged stands ranging from 12 to 197 years old. Logistic regression indicated that individual trees had a ∼50% probability of producing cones by age 30 years, which increased to 90% by age 100 years. Cone and seed production increased steadily with age or basal area at both the tree and stand level, with no evidence of declining seed production in trees older than 150 years. Using published seed:seedling ratios, we estimated that postfire recruitment will be limited by seed availability in stands for up to 50 years (on high-quality seedbeds) to 150 years (low-quality seedbeds) after fire. By quantifying these age and seed productivity relationships, we can improve our ability to predict the sensitivity of conifer seed production to a range of disturbance frequencies and thus anticipate changes in boreal forest resilience to altered fire regime.

Evaluation of Uranium Accumulation in Black Spruce Trees

This study evaluated the metal accumulation capacity of black spruce seedlings (Picea mariana) with a special focus on uranium and compared uptake from peat and podzol soil treated with various concentrations of uranyl nitrate hexahydrate. Bio-available indices for uranium in the substrates, accumulation factors and transfer factors for translocation of U between different plant organs were estimated. The results showed higher concentration of U in shoots with accumulation factors up to seven times greater than values determined in roots. Uranium accumulation in stems was several orders of magnitude higher than the metal content in roots and needles. Transfer from substrate to the plants was influenced by substrate-specific properties, resulting in higher uptake of U from soil than from peat. The pattern of U accumulation was consistent with that previously reported in field studies. Metal accumulation values also showed linear progression with Bio-available metal concentrations in the substrate suggesting that black spruce trees are best classified as bio-indicators of uranium content in underlying substrates rather than hyper accumulators of the metal.

Using a Standing-Tree Acoustic Tool to Identify Forest Stands for the Production of Mechanically-Graded Lumber

This study investigates how the use of a Hitman ST300 acoustic sensor can help identify the best forest stands to be used as supply sources for the production of Machine Stress-Rated (MSR) lumber. Using two piezoelectric sensors, the ST300 measures the velocity of a mechanical wave induced in a standing tree. Measurements were made on 333 black spruce (Picea mariana (Mill.) BSP) trees from the North Shore region, Quebec (Canada) selected across a range of locations and along a chronosequence of elapsed time since the last fire (TSF). Logs were cut from a subsample of 39 trees, and sawn into 77 pieces of 38 mm × 89 mm cross-section before undergoing mechanical testing according to ASTM standard D-4761. A linear regression model was developed to predict the static modulus of elasticity of lumber using tree acoustic velocity and stem diameter at 1.3 m above ground level (R2 = 0.41). Results suggest that, at a regional level, 92% of the black spruce trees meet the requirements of MSR grade 1650Fb-1.5E, whilst 64% and 34% meet the 2100Fb-1.8E and 2400Fb-2.0E, respectively. Mature stands with a TSF < 150 years had 11 and 18% more boards in the latter two categories, respectively, and therefore represented the best supply source for MSR lumber.

Distribution Patterns of Three Long-Horned Beetles (Coleoptera: Cerambycidae) Shortly After Fire in Boreal Forest: Adults Colonizing Stands Versus Progeny Emerging From Trees

We identified the factors that affect the early colonization of burned stands by adults and the progeny surviving in fire-killed black spruce trees for three cerambycid beetles: Acmaeops proteus proteus (Kirby), Acmaeops pratensis (Laicharting), and Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae) in the northern Canadian boreal forest. Furthermore, we measured if progeny emerging from burned trees was related to patterns of adults captured in traps the same year as the fire. Fire severity at the stand and landscape scales were the most important predictors for colonizing adults. Except for A. pratensis, thick-barked and lightly burned trees positively influenced the occurrence of surviving progeny at the tree level. Last-instar larvae of A. pratensis emerged from burned trees more often in severely burned landscapes. This may result from biotic interactions with intraguild species or predators. With the exception of A. pratensis, variables affecting the postfire abundance and occurrence pattern of adults were strikingly different from progeny emerging after fire. Progeny emerging from burned trees was almost exclusively related to tree- or stand level characteristics, whereas colonizing adults were correlated with variables measured at various spatial scales, and most often at the landscape scale. Moreover, A. proteus proteus and M. scutellatus scutellatus adults were more common in severely burned landscapes, although their progeny emerged more often in lightly or moderately burned trees. Host selection behavior within stands (e.g., host acceptance) by colonizing adults or host suitability for the larvae might have caused this discrepancy.

Frost Rings and White Earlywood Rings in Picea Mariana trees from the boreal plains, Central Canada

Dendroecological analysis of tree-ring anomalies can facilitate better environmental reconstructions provided that conditions leading to their formation are well understood. White earlywood rings (WER) constitute an anomaly not previously described and, like frost rings (FR), occur often in boreal coniferous species in central Canada. The objectives of this study were i) to examine the distribution of FR and WER in black spruce trees, ii) to measure and compare tracheid dimensions in WER and control rings and iii) to investigate potential causes of WER formation. Sampling was conducted in two regions of western Manitoba. At each of four sampling sites, ten black spruce trees were selected for stem analysis. Results indicated that FR were mainly formed in the smaller diameter, thin barked portion of the stem up to a height of 16m, whereas WER were almost uniformly distributed along the stem. Tracheids were measured for WER occurring in 1916, 1943 and 1970 and WER were found to have earlywood tracheids with significantly thinner cell walls compared to control rings. It is speculated that the formation of WER may be related to reduced hormone and carbohydrate availability in the early growing season. The potential linkage between WER and frost events, or other agents of defoliation, prior to ring formation merits further investigation.

Climate‐diameter growth relationships of black spruce and jack pine trees in borealOntario,Canada

To predict the long-term effects of climate change - global warming and changes in precipitation - on the diameter (radial) growth of jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] B.S.P.) trees in boreal Ontario, we modified an existing diameter growth model to include climate variables. Diameter chronologies of 927 jack pine and 1173 black spruce trees, growing in the area from 47°N to 50°N and 80°W to 92°W, were used to develop diameter growth models in a nonlinear mixed-effects approach. Our results showed that the variables long-term average of mean growing season temperature, precipitation during wettest quarter, and total precipitation during growing season were significant (alpha=0.05) in explaining variation in diameter growth of the sample trees. Model results indicated that higher temperatures during the growing season would increase the diameter growth of jack pine trees, but decrease that of black spruce trees. More precipitation during the wettest quarter would favor the diameter growth of both species. On the other hand, a wetter growing season, which may decrease radiation inputs, increase nutrient leaching, and reduce the decomposition rate, would reduce the diameter growth of both species. Moreover, our results indicated that future (2041-2070) diameter growth rate may differ from current (1971-2000) growth rates for both species, with conditions being more favorable for jack pine than black spruce trees. Expected future changes in the growth rate of boreal trees need to be considered in forest management decisions. We recommend that knowledge of climate-growth relationships, as represented by models, be combined with learning from adaptive management to reduce the risks and uncertainties associated with forest management decisions.

Multiscale assessment of the impacts of roads and cutovers on calving site selection in woodland caribou

Woodland caribou (Rangifer tarandus caribou) populations are declining worldwide, and predation is considered their most important limiting factor in North America. Caribou are known to reduce predation risk by spacing themselves away from predators and alternative prey. This strategy is now compromised by forestry activities that reduce the amount of suitable caribou habitat and trigger an increase in densities of alternative prey and predators. Our objective was to investigate the influence of predation risk and food availability on selection of a calving location by woodland caribou at three different spatial scales (from coarse to fine: annual home range, calving home range, and forest stand scales) in the boreal forest of Québec, Canada. Using GPS telemetry, we identified calving locations and assessed those using Resource Selection Functions. We determined habitat characteristics using digital ecoforest and topographic maps at the annual and calving home range scales, and with vegetation surveys at the forest stand scale. Caribou selected calving locations located at relatively high elevation and where road density was low, both at the annual and calving home range scales. Within the annual home range scale, they also selected calving locations where the proportion of young and old cutovers was lower than in random areas of similar size. At the forest stand scale, females calved away from roads and young cutovers, using stands where the basal area of black spruce and balsam fir trees was low. At this fine scale, females still selected calving locations located at a relatively high elevation and where the availability of food resources was lower than in random areas located within the same habitat type. The selection of a calving location was driven by predation risk from the largest to the finest spatial scale. Therefore, our results suggest that females may not be able to lower predation risk at larger scales, despite general avoidance of roads and cutovers. We recommend amalgamating all forestry activities within intensive management zones in order to spatially isolate large patches of suitable calving habitat from anthropogenic disturbances. If not possible, we recommend concentrating forestry activities in low-lying areas since caribou consistently selected for relatively high elevations at all scales.

Differences in crown characteristics between black (Picea mariana) and white spruce (Picea glauca)

Black spruce ( Picea mariana (Mill.) Britton, Sterns &amp; Poggenb.) and white spruce ( Picea glauca (Moench) Voss) are phylogenetically proximal species that differ in productivity. Crown characteristics of these two species have not been extensively studied, in spite of the importance of these two species to the Canadian boreal forest and the importance of tree crowns for understanding and modelling tree growth. In this paper, we characterize and compare the crown lengths, crown profiles (i.e., radii), shapes, and surface areas of these two species using 65 white spruce and 57 black spruce trees destructively sampled in the provinces of Alberta, Ontario, and Quebec, Canada. Crown length was measured on every sample tree, while crown profile was obtained by reconstructing crowns from branch measurements. Our results showed that crown lengths did not differ between these two species given the same tree size and growth conditions. However, these two species establish under different growth conditions resulting in crown length differences. Further, differences in crown radii and profiles were found even under the same growth conditions. White spruce trees had wider crown radii and profiles changed from a parabola to a cone shape under increased density. As a result, differences in crown surface areas were found.

Comparison of black spruce (Picea mariana) radial growth reduction in different soil moisture regimes during a spruce budworm (Choristoneura fumiferana) outbreak

The objective of this study was to determine if the stand‐level soil moisture regime had a significant effect on the reduction in black spruce (Picea mariana (Mill.) B.S.P.) radial growth during the most recent spruce budworm (Choristoneura fumiferana Clem.) outbreak in the boreal forest region of northeastern Ontario. We collected a stratified random sample of co-dominant black spruce trees from three moisture regimes and compared the reduction of radial growth during a spruce budworm outbreak between dry, moist, and wet stands. We focused on the most recent outbreak from 1975–1987, which we dated by dendrochronological analysis of black spruce increment cores from the Romeo Malette Forest near Timmins, Ontario. Samples collected from dry and moist sites showed significantly greater maximum radial growth reduction than those from wet sites. Mean growth reduction over the entire outbreak was not significantly different among moisture regimes but followed the same trend. We found no evidence of spatial autocorrelation in the growth reduction response, suggesting that the moisture effect was not confounded by location.

Implications of increased deciduous cover on stand structure and aboveground carbon pools of Alaskan boreal forests

Fire activity in boreal forests has increased recently with climate warming, altering stand structure and composition in many areas. Changes in stand dynamics have the potential to alter C cycling and biophysical processes, with feedbacks to global and regional climate. Here, we assess the interactions between fire, stand structure, and aboveground C accumulation and storage within boreal forests of interior Alaska, where increased fire severity is predicted to shift forest composition from predominantly black spruce (Picea mariana) to greater deciduous cover. We measured aboveground biomass and net primary productivity (ANPP) of trees and large shrubs, snags, and downed woody debris across 44 mid‐successional (20–59 years since fire) stands of varying deciduous importance value (IV), determined by relative density, basal area, and frequency of deciduous trees and large shrubs within each stand. Aboveground biomass, ANPP, and deciduous snag biomass increased significantly with increased deciduous IV and years since fire. Deciduous IV had little influence on evergreen snag biomass and downed woody debris, but both C pools decreased with years since fire. Forest type also affected stand structure and C pools. Black spruce stands had shorter trees with less basal area and aboveground biomass and slower rates of biomass accumulation and ANPP compared to those dominated by trembling aspen (Populus tremuloides) or Alaska birch (Betula neoalaskana). These parameters in black spruce stands were similar to mixed stands of black spruce and aspen but were often lower than mixed stands of black spruce and Alaska birch. Much of the biomass accumulation in deciduous stands was attributed to higher tree‐level ANPP, allowing individual stems of deciduous species to accumulate more stemwood/bark faster than black spruce trees. If increased fire activity shifts stand composition from black spruce to increased deciduous cover, ANPP, aboveground tree/large shrub biomass, and deciduous snag biomass will increase, leading to increased aboveground C pools in mid‐successional forest stands of interior Alaska. While species dominance shifts like these will impact aboveground patterns of landscape‐level C cycling in boreal forests, variations in soil C pools and forest properties like albedo must also be assessed to accurately determine implications for global and regional climate.

Lumber recovery and value of dead and sound black spruce trees grown in the North Shore region of Québec

Context To increase the wood supply to its industry, the government of Quebec has allocated dead and sound wood (recently dead merchantable stems, DSW) to the wood supply chain in addition to the annual allowable cut of living trees. However, DSW is often criticized by sawmillers for its perceived poor quality and lower value.

Till and vegetation geochemistry at the Talbot VMS Cu-Zn prospect, Manitoba, Canada: implications for mineral exploration

The Proterozoic Talbot VMS occurrence in the Flin Flon-Snow Lake terrane is buried under more than 100 m of Palaeozoic dolomites and Quaternary glacial till. Structurally controlled anomalies of Zn, Cu, Ag, Pb, Au, Mn, Hg, Cd, Co, Bi and Se in the clay fraction of till depth-profiles indicate upward element migration from the buried volcanogenic massive sulphide mineralisation and near-surface chemostratigraphic deposition. Principal component analysis and molar element ratios indicate that separation of the &lt;2 µm clay fraction reduces chemical heterogeneity and increases trace-element yield relative to the &lt;250 µm fraction of the till. The greatest anomalies occur at or below 30 cm depth and over faults, suggesting that elements were deposited in the till after upward migration through structures. The ratio Zn/Al in the &lt;250 µm fraction can be used as a proxy for Zn in the clay fraction, producing high-contrast anomalies. Carbon isotopic compositions indicate that these anomalies are related to organic carbon in the clay fraction. Humus, moss and black spruce bark are of limited use for exploration in this environment, because they accumulate atmospheric Pb and Cd, most likely from the Flin Flon smelter at 160 km NW. Black spruce tree rings that formed before smelter operations commenced indicate Zn and Mn anomalies in an uncontaminated sampling material. Much of the initial vertical migration of elements to the surface at the Talbot prospect was driven by upward advection of groundwater through fractures in the dolomite, resulting from a combination of subsurface karst collapse and remnant hydrostatic pressure during glacial retreat.

Dendrochronological evidence of shrub growth suppression by trees in a subarctic lichen woodland

Expansion of deciduous shrub species in open subarctic landscapes has been reported at several locations around the circumpolar region. However, few data are available to evaluate the response of shrub species in forested ecosystems. For this study, we conducted a dendrochronological analysis to compare the establishment and growth of Betula glandulosa Michx. individuals prior to and after an experimental removal of tree cover (1987) in a lichen woodland located at the boreal forest – tundra ecotone. Tree removal was followed by a B. glandulosa recruitment pulse. It is likely that the newly established seedlings benefited more from heavy trampling during tree removal, which destroyed the lichen cover, than from tree removal itself. A strong growth increase after tree removal suggests that the black spruce tree cover suppressed B. glandulosa growth prior to 1987. Moreover, while radial growth for the period prior to tree removal was not a function of the number of growing degree-days during the growing season, the same climatic variable explained 46% of the growth variability in the second period. These results suggest that the presence of a tree cover might limit the response of shrub species to climate change in forested ecosystems.