Stem In Black Spruce Research Articles

Mixed stands of black spruce (Picea mariana) and tamarack (Larix laricina) offer high secondary growth in eastern boreal forests of Canada

The Canadian boreal forest is still lacking investigation into compatible species mixtures that can lead to higher growth rates than monospecific or pure stands. The effect of species mixtures on stand productivity can vary with stem density, species proportion, site characteristics, and climate variation. We investigated mixed stands of black spruce (Picea mariana) and tamarack (Larix laricina) in eastern Canadian boreal forests. Using modern forest survey data, we analyzed stand basal area variation in 756 mature stands exclusively composed of these two species over a study area spanning 535,000 km². We generated a linear relationship between mixed stand basal area and stem density, and the residual of this relation was used as response variable named ‘residual basal area’. Positive and negative deviations of residual basal area were analysed with generalized additive models and quantile regressions with tamarack basal area, climate, and site characteristics as explanatory variables. The selected model included tamarack basal area, mean seasonal precipitation, degree days, mean annual temperature, stand age, latitude, longitude, and the type of surficial deposit. Tamarack exhibited a linear positive effect on predicted residual basal area. The most significant effect was observed from the interaction between tamarack basal area and stand age, predicting positive residual basal area of 16 m² ha−1 when stand aged was 150 years old and tamarack basal area was between 12 and 17 m² ha−1. Quantile regressions revealed that tamarack could enhance basal area while increasing black spruce stem size and density. Landscape managers may consider the establishment of mixed black spruce and tamarack stands to favor secondary growth in eastern Canadian boreal forests.

Early influences of tamarack (Larix laricina) on black spruce (Picea mariana) and its immediate environment in plantations

Mixed plantations are garnering increased attention due to their potential to provide a broader array of benefits compared to monocultures. Although numerous studies have indicated promising complementarity between black spruce ( Picea mariana) and tamarack ( Larix laricina), few have delved into individual tree growth interactions to thoroughly assess early growth complementarity. We sampled 119 planted black spruce and their immediate environment to quantify and qualify any differences between two conditions in young plantations: mixed tamarack (“mixtures”) and black spruce monocultures (“monocultures”) within young plantations. We investigated the effect of neighbouring under four perspectives: tree competition, microenvironment, foliar nutrients, and soil nutrients. Our results showed increased values for black spruce foliar nitrogen total concentration, soil pH, and canopy closure in mixtures compared to monocultures. Furthermore, black spruce stem volume was increased by 38.1% in mixture compared to monoculture. Black spruce stem volume was negatively affected (86% decrease) by the combined effect of shrubs and non-crop trees under high competition pressure, despite the plantation being mechanically released in 2017. Collectively, our results suggest that black spruce growing in mixtures holds a greater growth potential than black spruce in monocultures.

Characterizing wood density–climate relationships along the stem in black spruce (Picea mariana (Mill.) B.S.P.) using a combination of boosted regression trees and mixed-effects models

The relationships between climate and wood density components, i.e. minimum, maximum and average ring density, have been characterized mainly at breast height, while little information is available for other stem heights. This work aimed to (1) identify the significant climate variables related to ring density components in black spruce (Picea mariana (Mill.) B.S.P.) and (2) assess whether their effects vary significantly along the stem. Densitometric data were obtained from 68 black spruce trees from northwestern Ontario, Canada. Six discs along the stem, from stump to base of the live crown, were sampled. For each sample height and density component, we first developed mixed-effects models using ring width and cambial age as predictors. Monthly climate variables were later integrated into the models. The candidate climate variables were pre-selected using the boosted regression trees method. In addition to observed density–climate relationships, a significant effect of sample height was found. Findings revealed that the relationships were similar in nature but varied in strength and timing along the stem. The wood density variation showed delayed sensitivities to some climate variables among sampling heights. Such delayed responses may be caused by the axial progression of water requirement and of hormonal and photosynthetic allocation along the stem throughout the growing season.

Comparison of wood density in roots and stems of black spruce before and after commercial thinning

Abstract Roots play an important physiological and mechanical role in the survival and growth of a tree, but also in the success of silvicultural treatments. Studies comparing the xylem in roots and stems have shown that conifer tracheids tend to be wider and longer in roots, which renders root wood less dense and more susceptible to cavitation and embolism. The increased radial growth often observed after thinning may induce changes in wood anatomy that could alter wood properties, such as wood density, in the stem and roots. The aim of this study was to compare growth, wood density and tracheid dimensions between the stem and roots of black spruce trees growing in the boreal forest. We also evaluated whether these wood properties were altered by the application of a commercial thinning treatment. Six black spruce trees were harvested in four commercially thinned stands. Samples were collected from the stem and two locations of each root. Radial growth, wood density and tracheid dimensions were measured on each sample. Results show that all wood density components, especially earlywood density, were higher in the roots than in the stem in black spruce. This denser wood in roots might provide increased safety against cavitation in a part of the xylem where hydraulic stresses are higher. After thinning, growth was increased in the stem and particularly in roots, resulting in slight wood density decreases, which should not influence the vulnerability of roots to cavitation or wood quality in the stem. These results lead us to suppose that the hydraulic network of the black spruce root system may not be so vulnerable to cavitation.

A Fine-Scale Examination ofLarix laricinaandPicea marianaAbundances along Abiotic Gradients in an Adirondack Peatland

Abstract Wetland research has described changes in plant communities along environmental gradients, however, little is known about the relationship between fine-scale hydrologic and abiotic factors and the relative abundances of individual, co-occurring species. Larix laricina (Eastern Larch) and Picea mariana (Black Spruce) are the 2 dominant tree species in open boreal peatlands in the northeastern US. In order to describe abiotic gradients that correlate with species abundances at local spatial scales, we collected data on Eastern Larch and Black Spruce stem abundances, groundwater pH, conductivity, depth to water table, water temperature, dissolved oxygen, and canopy closure from 42 plots along 6 transects in an Adirondack wetland. We correlated stem abundances with each of the abiotic variables and then used regression to explain variation in stem abundances of the 2 species along those abiotic gradients. Percent canopy closure explained 56% of the variability in Eastern Larch stem abundance, and dep...

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited.

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation,’ have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law,’ since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Timing of growth reductions in black spruce stem and branches during the 1970s spruce budworm outbreak1This article is one of a selection of papers from the 7th International Conference on Disturbance Dynamics in Boreal Forests.

Spruce budworm ( Choristoneura fumiferana (Clemens)) defoliation is known to regularly produce radial growth decrease in black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) in the boreal forest of Quebec. Some studies have already shown that the first year of defoliation does not induce growth losses in the stem but could occur in other tree parts. We therefore examined the timing and duration of the growth reduction caused by the last outbreak in black spruce by also considering the branches. More than 79% of branches and 65% of stems exhibited a >40% growth decrease.The reduction was first registered in the upper part of the stem before being detected lower in the stem in 87% of the trees. Probabilities of growth reduction in the upper part of the stem were highest in 1976 and 1977. In the lower stem, the probabilities were highest in 1978. An interesting finding was that in 69% of the studied stands, the probability of growth reduction started earlier (1–2 years) in the branches than in the stem at 1.3 m. Branch analysis should be considered whenever questions arise in regard to the evolution of spruce budworm defoliation as well as the timing of observed growth reduction in black spruce.

Upland black spruce stand development 17 years after cleaning and precommercial thinning

Density management is often used by silviculturists to guide stand composition and development. We examined the effects of cleaning (hardwood removal) and four levels of precommercial thinning (0, 20, 35 and 50% basal area removal) on stand development in a dense, 24-year-old upland black spruce (Picea mariana [Mill.] BSP) plantation near Beardmore, Ontario. Immediately before treatment, stand densities and basal areas for all species and for black spruce averaged 7375 and 6415 stems ha-1, and 27.9 and 20.5 m2 ha-1, respectively. Seventeen years after treatment, black spruce total stand volume (VT) was higher in the cleaned, unthinned plots (243 m3 ha-1) than in the untreated controls (171 m3 ha-1) while total stand volume increment of all species combined was similar in these two treatments. Compared with cleaning alone, thinning cleaned plots from below increased quadratic mean diameters (DQ) by up to 9% but decreased VT by up to 28%. At plantation age 41, increases in black spruce densities of 1000 stems ha-1 resulted in mean decreases of 0.6 cm in DQ and mean increases of 43 m3 ha-1 in VT. Endemic black spruce stem mortality rates decreased with thinning intensity, with mortality concentrated in the smallest size classes. In some plots, mortality was increased by wind or snow damage, and by root rots. Height increment of dominant trees was unaffected by thinning. Projected yields at age 55 (the physical rotation age—the age at which maximum mean annual increment occurs) suggest the heaviest precommercial thinning could increase quadratic mean diameter from 16.1 to 17.7 cm, but decrease merchantable stand volume from 292 to 225 m3 ha-1. Results indicate that total black spruce fibre yields and product value on these sites will be maximized in denser stands. Cleaning appears to offer greater benefits for black spruce fibre production than precommercial thinning. Key words: black spruce, precommercial thinning, cleaning, density management, projected yields

Effect of aspen ( Populus tremuloides) as a companion species on the growth of black spruce ( Picea mariana) in the southwestern boreal forest of Quebec

In the western boreal forest of Quebec, black spruce stand productivity is approximately 1 m 3/ha/year. The low productivity of these stands is often attributed to the paludification process, which is sustained by low quality black spruce litter and the influence of black spruce on soil moisture. In contrast, aspen hasten nutrient cycling, suggesting that the presence of aspen in black spruce-dominated stands could offset the effect of black spruce on soil processes and positively affect stand productivity. We hypothesised that aspen in black spruce-dominated stands could: (1) increase black spruce DBH, height and volume per stem, (2) increase black spruce productivity without affecting black spruce volume in the stand, and (3) increase total stand volume. In 2001, twelve 14 m diameter plots were sampled for DBH and height of every stem on three black spruce-dominated sites containing various proportions of aspen. Using stem analysis, the time to grow from a height of 5 m to a height of 10 m was determined on three dominant black spruces in each plot. Statistical analyses revealed that DBH, height and volume per black spruce stem were not affected by aspen. However, total black spruce volume decreased with increasing aspen basal area in sites 2 and 3, suggesting that the presence of aspen reduced black spruce density. In site 1, black spruce volume was not affected by aspen, indicating, for total stand productivity, a net gain in aspen fibre. Along a gradient of increasing aspen basal area, the time to grow 5 m decreased in sites 1 and 3. These results suggest that the presence of aspen influences black spruce productivity, although this influence is site-specific and could be dependent on the proportion of aspen, its hierarchical position in the canopy, and the nutrient status of the site. To some extent, this could explain the absence of a general trend concerning mixed stand productivity.

Micro‐synchrotron x‐ray fluorescence of the metal distribution in a black spruce tree stem: evidence for radial mobility

AbstractMicro‐synchrotron radiation x‐ray fluorescence has been used to examine the metal distribution across an entire black spruce stem. The results show the individual elements to be transported and sequestered in different ways so that apparent elemental mobility within the stem changes from element to element. The results suggest that a detailed knowledge of the behavior of each element is required before pollution chronologies can be inferred from dendroanalysis. Copyright © 2003 John Wiley & Sons, Ltd.

Black Spruce Growth and Understory Species Diversity with and without Sheep Laurel

Growth and understory species diversity of black spruce [Picea mariana (Miller) B.S.P.] planted in central Newfoundland at contiguous sites with and without dense cover of sheep laurel (Kalmia angustifolia L.) were compared. Black spruce stem density and volume per hectare were calculated by sampling 10 circular quadrats (50 m2), and the cover of all plant species was determined by sampling 20 quadrats (1 m2) in each site. In addition, 10 randomly sampled planted black spruce samplings from each site were analyzed for stem height, basal diameter, and foliar chemistry. Results showed a significantly lower stem height and basal diameter (65 and 51%, respectively) at the site with dense sheep laurel cover (36%) compared with the site with sparse sheep laurel cover (<1% sheep laurel cover, and henceforth referred to as the non‐sheep laurel site for simplicity). Black spruce grown at the sheep laurel dominated site contained significantly higher quantities of Ca, Al, Fe, and K in the needles than that grown at the non‐sheep laurel site. The sheep laurel dominated site also had a significantly higher mean organic matter depth of 8.3 cm compared with 5.6 cm at the non‐sheep laurel site. Canonical correspondence analysis (CCA) of the species cover data clearly separated the sheep laurel dominated plots from the non‐sheep laurel plots. The sheep laurel dominated site had reduced species richness of vascular plants but increased species richness for lichens compared with the non‐sheep laurel site. Allelopathy associated with phenol‐induced soil nutrient imbalance and nutrient stress is a possible cause for black spruce growth inhibition at the sheep laurel dominated site.

Black spruce and vegetation response to chemical and mechanical site preparation on a boreal mixedwood site

The growth and development of outplanted black spruce (Picea mariana (Mill.) BSP) and competing vegetation five growing seasons after mechanical and chemical site preparation treatments are presented. The largest stem volume increase for black spruce coupled with the lowest vegetation indices for competing trees and shrubs were recorded on the treatment consisting of chemical site preparation with liquid hexazinone applied at 3.1 kg active ingredient (a.i.)·ha-1 followed by chemical tending in the second and fourth growing season with glyphosate applied at 1.78 kg a.i.·ha-1. Black spruce stem volume growth was second highest and the vegetation indices for competing trees and shrubs the highest, on plots treated with hexazinone site preparation. Among mechanical treatments, black spruce stem volume was highest on plots treated with mixed-mound site preparation. No other mechanical site-preparation treatment improved the growth of black spruce over boot-screef site preparation alone. The vegetation index of trembling aspen (Populus tremuloides Michx.) was reduced on mixed-mound and area-mixed site preparation treatments. The vegetation index of red raspberry (Rubus idaeus L.) was reduced on area-mix and area- and strip-screef treatments. By the fifth growing season, site-preparation treatment had little effect on the comparative growth of grasses and forbs. High-speed strip-mixing with 80 cm wide strips spaced at 2-m centres, on deep, fertile, silty loams of Site Region 3W-Lake Nipigon, does not appear feasible as an alternative to chemical site preparation or conventional manual and mechanical site preparation.

Black spruce and vegetation response to chemical and mechanical site preparation on a boreal mixedwood site

The growth and development of outplanted black spruce (Picea mariana (Mill.) BSP) and competing vegetation five growing seasons after mechanical and chemical site preparation treatments are presented. The largest stem volume increase for black spruce coupled with the lowest vegetation indices for competing trees and shrubs were recorded on the treatment consisting of chemical site preparation with liquid hexazinone applied at 3.1 kg active ingredient (a.i.)·ha-1 followed by chemical tending in the second and fourth growing season with glyphosate applied at 1.78 kg a.i.·ha-1. Black spruce stem volume growth was second highest and the vegetation indices for competing trees and shrubs the highest, on plots treated with hexazinone site preparation. Among mechanical treatments, black spruce stem volume was highest on plots treated with mixed-mound site preparation. No other mechanical site-preparation treatment improved the growth of black spruce over boot-screef site preparation alone. The vegetation index of trembling aspen (Populus tremuloides Michx.) was reduced on mixed-mound and area-mixed site preparation treatments. The vegetation index of red raspberry (Rubus idaeus L.) was reduced on area-mix and area- and strip-screef treatments. By the fifth growing season, site-preparation treatment had little effect on the comparative growth of grasses and forbs. High-speed strip-mixing with 80 cm wide strips spaced at 2-m centres, on deep, fertile, silty loams of Site Region 3W-Lake Nipigon, does not appear feasible as an alternative to chemical site preparation or conventional manual and mechanical site preparation.