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Yves Bergeron - One of the best experts on this subject based on the ideXlab platform.
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Persistence of balsam fir and Black Spruce populations in the mixedwood and coniferous bioclimatic domain of eastern North America.
Ecology and evolution, 2019Co-Authors: Yassine Messaoud, Venceslas Goudiaby, Yves BergeronAbstract:The boreal ecocline (ca 49°N) between the southern mixedwood (dominated by balsam fir) and the northern coniferous bioclimatic domain (dominated by Black Spruce) may be explained by a northward decrease of balsam fir regeneration, explaining the gradual shift to Black Spruce dominance. 7,010 sample plots, with absence of major disturbances, were provided by the Quebec Ministry of Forest, Fauna, and Parks. The regeneration (sapling abundance) of balsam fir and Black Spruce were compared within and between the two bioclimatic domains, accounting for parental trees, main soil type (clay and till) and climate conditions, reflected by summer growing degree-days above 5°C (GDD_5), total summer precipitation (May-August; PP_MA). Parental trees and soil type determined balsam fir and Black Spruce regeneration. Balsam fir and Black Spruce, respectively, showed higher regeneration in the mixedwood and the coniferous bioclimatic domains. Overall, higher regeneration was obtained on till for balsam fir, and on clay soils for Black Spruce. GDD_5 and PP_MA were beneficial for balsam fir regeneration on clay and till soils, respectively, while they were detrimental for Black Spruce regeneration. At a population level, balsam fir required at least 28% of parental tree basal area in the mixedwood, and 38% in the coniferous bioclimatic domains to maintain a regeneration at least equal to the mean regeneration of the whole study area. However, Black Spruce required 82% and 79% of parental trees basal area in the mixedwood and the coniferous domains, respectively. The northern limit of the mixedwood bioclimatic domain was attributed to a gradual decrease toward the north of balsam fir regeneration most likely due to cooler temperatures, shorter growing seasons, and decrease of the parental trees further north of this northern limit. However, balsam fir still persists above this northern limit, owing to a patchy occurrence of small parental trees populations, and good establishment substrates.
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Prescribed burning after clearcut limits paludification in Black Spruce boreal forest
Forest Ecology and Management, 2016Co-Authors: Sébastien M. Renard, Nicole J. Fenton, Benoit Lafleur, Sylvie Gauthier, Yves BergeronAbstract:Abstract Paludification, the accumulation over the mineral soil of poorly decomposed organic matter mainly originating from Sphagnum spp., transforms Black Spruce ( Picea mariana ) boreal forests into forested peatlands in the prolonged absence of fire, which diminishes forest productivity. High-severity wildfires reset this process by burning the soil organic layer (SOL) and reinitiating forest succession. In contrast, low severity wildfires impact mainly the soil surface and tree layer and do not significantly reduce SOL depth. In the Clay Belt region of eastern Canada, an area prone to paludification, the current forest harvest practice (careful logging around advanced growth [CLAAG]) removes trees but has little impact on the SOL and the understorey vegetation. This is thought to further promote paludification, which consequently reduces forest productivity. Conversely, clearcut (CC) disturbs the SOL and the understorey vegetation, and is thought to favor tree growth. Furthermore, prescribed burning after clearcut (CCPB) is used as a site preparation technique, but may also be used to control paludification as it can burn part of the organic soil layer. Using a retrospective approach, our study examines three hypotheses: compared to CLAAG, CC and CCPB: (1) have positive effects on soil conditions (e.g. decomposition level and pH), (2) reduce Sphagnum spp. and ericaceous shrub cover and (3) result in enhanced Black Spruce growth. We sampled 22 sites in which we measured SOL characteristics (e.g. depth, decomposition state), understorey vegetation cover and Black Spruce growth. Compared to CLAAG, CCPB resulted in increased soil decomposition level and higher pH. CCPB also reduced Sphagnum spp. cover but not ericaceous shrub cover. Black Spruce growth rate was higher following CCPB than CC, and mean dominant tree height was marginally higher following CCPB than CLAAG and CC. Our results demonstrate that CCPB is beneficial to Black Spruce growth, presumably through its effects on forest understorey and SOL chemistry. While not similar to a high severity fire, prescribed burning after clearcut in paludified stands on the Clay Belt emulates some wildfire effects such as increasing soil pH. We suggest that unlike CLAAG, prescribed burning after clearcut can restore Black Spruce stand productivity and should be considered in the context of forest ecosystem management.
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Quality of growth substrates of post-disturbed lowland Black Spruce sites for Black Spruce (Picea mariana) seedling growth
New Forests, 2007Co-Authors: M. Lavoie, D. Pare, Yves BergeronAbstract:Black Spruce ( Picea mariana (Mill.) BSP) is the most important commercial tree species in the eastern boreal forest of Canada. Only limited work has been conducted to assess the quality of the various substrates that are found on post-disturbed sites prone to paludification having an effect on Black Spruce seedling growth. The objectives of this study were (1) to use a pot test to assess Black Spruce seedling performance on substrates found at the soil surface, in the rooting zone of undisturbed soil, at depths that become available to Spruce roots after soil disturbance by wildfire or through management; and (2) to determine the nutritional quality of these substrates when constraints of poor drainage are artificially removed. Black Spruce growth was greatest with fibric Pleurozium in the rooting zone, and with burned fibric Pleurozium and living Sphagnum at the soil surface. Good seedling growth on different substrates found in the rooting zone was associated with higher N and P foliar concentrations. Based on these results, we recommend targeted planting of Black Spruce seedlings in substrates of Pleurozium origin and the development of management techniques that promote Pleurozium schreberi .
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Relationships between microsite type and the growth and nutrition of young Black Spruce on post-disturbed lowland Black Spruce sites in eastern Canada
Canadian Journal of Forest Research, 2007Co-Authors: M. Lavoie, D. Pare, Yves BergeronAbstract:The surface of the soil in recently harvested or burned lowland Black Spruce (Picea mariana (Mill.) BSP) sites is composed of a fine mosaic of different bryophytes (mostly Sphagnum spp. and feathermosses), disturbed organic material originating mostly from mosses at different stages of decay, and exposed mineral soil. Growth substrates were compared in lowland Black Spruce stands regenerating after either careful logging or wildfire. The 3-year annual increment for Black Spruce seedlings was greatest with substrates of feathermosses, mainly Pleurozium schreberi (Brid.) Mitt., fibric material of P. schreberi origin, and a mixture of fibric P. schreberi and humic materials; it was least with fibric Sphagnum spp., mineral soil, and decaying wood substrates. The most favourable substrates for growth were characterized by better Black Spruce N and P foliar status. Our results also suggest that categories of growth substrates in the rooting zone reflect nutritional quality better than categories of growth subst...
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Effect of aspen (Populus tremuloides) as a companion species on the growth of Black Spruce (Picea mariana) in the southwestern boreal forest of Quebec
Forest Ecology and Management, 2005Co-Authors: Sonia Légaré, Yves Bergeron, D. PareAbstract:Abstract In the western boreal forest of Quebec, Black Spruce stand productivity is approximately 1 m3/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.
Janusz J. Zwiazek - One of the best experts on this subject based on the ideXlab platform.
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Responses of Black Spruce (Picea mariana) and tamarack (Larix laricina) to flooding and ethylene
Tree Physiology, 2003Co-Authors: M. Anisul Islam, S. Ellen Macdonald, Janusz J. ZwiazekAbstract:Black Spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in the boreal peatlands of Alberta, Canada, where low nutrient availability, low soil temperature and a high water table limit their growth. Effects of flooding for 28 days on morphological and physiological responses were investigated in greenhouse-grown Black Spruce and tamarack seedlings in a growth chamber. Flooding reduced root hydraulic conductance, net assimilation rate and stomatal conductance, and increased water-use efficiency (WUE) and needle electrolyte leakage in both species. Although flooded Black Spruce seedlings maintained higher net assimilation rates and stomatal conductance than flooded tamarack seedlings, flooded tamarack seedlings were able to maintain higher root hydraulic conductance than flooded Black Spruce seedlings. Needles of flooded Black Spruce developed tip necrosis and electrolyte leakage after 14 days of flooding, and these symptoms were subsequently more prominent than in needles of flooded tamarack seedlings. Flooded tamarack seedlings exhibited no visible injury symptoms and developed hypertrophied lenticels at their stem base. Application of exogenous ethylene resulted in a significant reduction in net assimilation, stomatal conductance and root respiration, whereas root hydraulic conductivity increased in both species. Thus, although flooded Black Spruce seedlings maintained a higher stomatal conductance and net assimilation rate than tamarack seedlings, Black Spruce did not cope with the deleterious effects of prolonged soil flooding and exogenous ethylene as well as tamarack.
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Responses of Black Spruce (Picea mariana) and tamarack (Larix laricina) to flooding and ethylene
Tree Physiology, 2003Co-Authors: M. Anisul Islam, S. Ellen Macdonald, Janusz J. ZwiazekAbstract:Black Spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in the boreal peatlands of Alberta, Canada, where low nutrient availability, low soil temperature and a high water table limit their growth. Effects of flooding for 28 days on morphological and physiological responses were investigated in greenhouse-grown Black Spruce and tamarack seedlings in a growth chamber. Flooding reduced root hydraulic conductance, net assimilation rate and stomatal conductance, and increased water-use efficiency (WUE) and needle electrolyte leakage in both species. Although flooded Black Spruce seedlings maintained higher net assimilation rates and stomatal conductance than flooded tamarack seedlings, flooded tamarack seedlings were able to maintain higher root hydraulic conductance than flooded Black Spruce seedlings. Needles of flooded Black Spruce developed tip necrosis and electrolyte leakage after 14 days of flooding, and these symptoms were subsequently more prominent than in needles of flooded tamarack seedlings. Flooded tamarack seedlings exhibited no visible injury symptoms and developed hypertrophied lenticels at their stem base. Application of exogenous ethylene resulted in a significant reduction in net assimilation, stomatal conductance and root respiration, whereas root hydraulic conductivity increased in both species. Thus, although flooded Black Spruce seedlings maintained a higher stomatal conductance and net assimilation rate than tamarack seedlings, Black Spruce did not cope with the deleterious effects of prolonged soil flooding and exogenous ethylene as well as tamarack.
Azim U. Mallik - One of the best experts on this subject based on the ideXlab platform.
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Black Spruce (Picea mariana) restoration in Kalmia heath by scarification and microsite mulching
Forest Ecology and Management, 2016Co-Authors: Azim U. Mallik, Dmitri KravchenkoAbstract:Abstract Canopy removing disturbance such as clearcutting and fire in nutrient-poor boreal and temperate forests often create shrub-dominated vegetation causing significant delay in forest succession. Lack of favourable microsites for Black Spruce seedling establishment and growth has been identified as the primary cause for conifer regeneration failure in post-fire Kalmia heath in eastern Canada. The aim of this study was to compare the growth performance of Black Spruce planted in scarified plots and in microsites developed by a novel technique called micro-site mulching (MSM) in Kalmia heaths. We hypothesized that because of vegetation removal and exposure of mineral soil in scarified and MSM treatments, planted Black Spruce would suffer from frost heaving and animal browsing, but these treatments may offer better seedling growth by ameliorating the inhibitory effects of Kalmia organic matter and providing with favourable soil moisture, soil temperature, soil respiration and nutrient availability. We conducted this study in a 13 year-old post-fire Kalmia heath in Triton Brook, Newfoundland, Canada (48°30′N, 50°00′W). We measured Black Spruce seedling survival and growth annually for three complete growing seasons and soil nutrient availability one year post-planting. In all three treatments Black Spruce seedling survival was >90%. About 20% of the seedlings in scarified and MSM treatments suffered herbivore damage and frost heaving with little damage in control plots. Black Spruce in scarified and MSM plots were associated with significantly higher growth than control, with differences amplified each consecutive year since planting. Higher seedling growth in scarified and MSM plots was associated with higher soil moisture, lower organic matter content, and lower soil temperature. Soil nutrient differences in treatments had little effect on seedling growth. Since MSM treatment produced substantially less soil disturbance with similar or better seedling growth than scarification, we suggest MSM as a preferred site preparation technique in Kalmia heath in contexts where large-scale soil disturbance by standard mechanized scarification is undesirable. The novelty of his paper is the development of MSM as a potential alternative to scarification in creating suitable microsites for planted Black Spruce to restore forest cover in ericaceous heaths. However, an operationally suitable MSM tool must be developed and a longer-term (10 years) monitoring is necessary before the method can be applied as a restoration tool.
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Selected ectomycorrhizal fungi of Black Spruce (Picea mariana) can detoxify phenolic compounds of Kalmia angustifolia
Journal of chemical ecology, 2006Co-Authors: Rensen Zeng, Azim U. MallikAbstract:Allelopathy has been implicated as a factor contributing toward failure of Black Spruce (Picea mariana) regeneration in Kalmia angustifolia-dominated sites in eastern Canada. Several phenolic acids of Kalmia origin inhibit primary root growth of Black Spruce. We tested the hypothesis that some well-adapted conifer ectomycorrhizae can degrade and detoxify water-soluble phenolic compounds produced by Kalmia and use the degraded products as a carbon source to stimulate growth. We found that hyphal growth of Paxillus involutus, a common ectomycorrhizal fungus of Black Spruce, was stimulated by water leachates of Kalmia leaf and litter. An equimolar mixture of three phenolic acids (ferulic, o-coumaric, and o-hydroxyphenylacetic acid), commonly found in Kalmia, had no negative effects on fungal growth at 1 mM concentration. The o-hydroxyphenylacetic (o-HPA) acid, which is known to be toxic to Black Spruce, was found to stimulate the growth of Laccaria laccata, L. bicolor, and P. involutus (isolates 211804 and 196554) by 38.4, 29.3, 25.0, and 18.9%, respectively, at 1 mM. Pure ferulic, o-coumaric, and o-HPA acids were degraded by 100, 98, and 79.5%, respectively, within 10 d in the presence of P. involutus 211804. However, L. laccata could not tolerate high concentrations of the Kalmia leachates. P. involutus and L. bicolor used o-HPA acid as a carbon source when cultured in noncarbon nutrient medium. The 0.5 and 0.2 mM o-HPA acid inhibited the root growth of Black Spruce. However, after solutions had been exposed to a culture of P. involutus, they had no significant effect on seedling growth of Black Spruce. We concluded that some ectomycorrhizal fungi, such as P. involutus and L. bicolor, are able to degrade Kalmia phenolics. Our findings point to a mechanism by which ectomycorrhizal species can control species interactions in higher plants by changing the rhizosphere chemistry.
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Can Kalmia angustifolia interference to Black Spruce (Picea mariana) be explained by allelopathy
Forest Ecology and Management, 2002Co-Authors: Inderjit, Azim U. MallikAbstract:Abstract Allelopathic interference of Kalmia angustifolia (Ericaceae) to the growth and establishment of Black Spruce (Picea mariana) has been suggested by several authors. The greenhouse studies suggested that Kalmia has potential for nutrient interference. However, these studies do not eliminate probable involvement of allelopathy. Field studies indicate that soils associated with Kalmia were nutrient-poor particularly for nitrogen, phosphorus, iron, and manganese, and support the hypothesis that Kalmia has dominated microsites that were nutrient-poor prior to its colonization. The questions addressed in this paper are (i) Is Kalmia interference to Black Spruce growth explained by allelopathy? (ii) Can Kalmia–Black Spruce allelochemical interactions be better explained by ecosystem-level approach to allelochemicals rather than disturbance-related regeneration ecology of Kalmia? At present, we do not have compelling direct evidence to support allelopathy as a mechanism of Kalmia interference to Black Spruce. However, organic molecules released from Kalmia into the environment may influence soil mineralization, mycorrhizae, nutrient dynamics, and soil microbial ecology. We hypothesize that synergistic interaction of ecological factors may better explain the interference mechanism of Kalmia.
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Black Spruce Growth and Understory Species Diversity with and without Sheep Laurel
Agronomy Journal, 2001Co-Authors: Azim U. MallikAbstract: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 m 2 ), and the cover of all plant species was determined by sampling 20 quadrats (1 m 2 ) 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 (
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Growth and physiological responses of Black Spruce (Picea mariana) to sites dominated byLedum groenlandicum.
Journal of chemical ecology, 1996Co-Authors: Inderjit, Azim U. MallikAbstract:Growth and physiological parameters of Black Spruce planted eight years previously were compared at sites with and withoutLedum groenlandicum to quantify the adverse effects on Black Spruce inLedum sites. Tree height, crown diameter, and dry weights of stems, branches, and needles of Black Spruce were significantly less at theLedum-dominated sites. Annual stem height, basal diameter, growth ring width, and cumulative wood volume of Black Spruce were significantly reduced in theLedum sites compared to those of the non-Ledum sites. Yearly growth of Black Spruce in the first seven years after planting was more affected in theLedum site than the eighth year's growth. Foliar nutrient analysis of Black Spruce in theLedum site showed an overall imbalance in nutrient accumulation. Black Spruce growing in theLedum site had higher foliar concentrations of Al, Ca, Fe, Ni, and S and lower concentrations of N and Si than those growing in the non-Ledum site. Black Spruce growing in theLedum site also had a higher foliar phenolic content. Preliminary experiments suggest thatLedum has the potential to leach water-soluble phenolics to its immediate organic soil.
Chhun-huor Ung - One of the best experts on this subject based on the ideXlab platform.
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Ecogeographic variation in Black Spruce wood properties across Quebec’s boreal forest
Forest Ecology and Management, 2016Co-Authors: Guillaume Giroud, Jean Bégin, Maurice Defo, Chhun-huor UngAbstract:Abstract Ecogeographic variation in Black Spruce clear wood properties was investigated for the two main vegetation types of the managed boreal forest of the province of Quebec, Canada. In total, 409 co-dominant and dominant trees from 82 mature stands were sampled. Basic wood density, modulus of elasticity and microfibril angle were measured using SilviScan. Mature fiber length was determined using a high-resolution Fiber Quality Analyzer. Wood growing in pure Black Spruce stands had longer mature fibers, a significantly denser wood with better mechanical characteristics than the wood growing in mixed stands with balsam fir. All wood properties were clearly influenced by radial growth and species composition. Given the limited number of sample plots for mapping purposes, a two-stage modeling approach was assessed to predict stand-level estimates of Black Spruce clear wood properties. This scaling-up method, based on field measurements and ring data from 3350 inventory plots, has improved the performance of all models. Stand-level models explained 47%, 57%, 63% and 63% of variance in wood density, modulus of elasticity, microfibril angle and mature fiber length respectively with estimated root mean square errors of 8.9 kg/m3, 0.52 GPa, 0.60° and 0.06 mm. An east-west gradient in Black Spruce clear wood properties was revealed as possibly the by-product of the change in relative proportions of both studied vegetation types across the study area. The results indicate that the Black Spruce wood from western regions of the managed boreal forest has a better potential for producing pulp and paper, lumber or engineered products due to its longer mature fibers and higher mechanical properties.
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Comparing height growth and biomass production of Black Spruce trees in logged and burned stands
Forest Ecology and Management, 2004Co-Authors: Jean-claude Ruel, Chhun-huor Ung, R. Horvath, Alison D. MunsonAbstract:The strategy of using advanced layering for regenerating logged Black Spruce stands has become a common practice. Compared with natural post-fire Black Spruce stands, this strategy may alter stand structure with a possible change in stand productivity. Using harvested tree data from sample plots established in burned and logged stands, 50 years after disturbance, and on similar soils, we compared the structure, height growth, and biomass allocation of both types of stands. Stem analysis revealed that Black Spruce trees in logged stands reached their maximum height growth later and at a concomitant lower level than Black Spruce trees in burned stands. Biomass production was comparable between stand types but was reduced when ericaceous shrubs were abundant. Compared to natural post-fire stands, logged stands present a shift of biomass allocation to branches and to leaves. These mechanisms are interdependent and represent the tree adjustment to the altered structure in logged stands characterised by the fragmented canopy with the increase of ericaceous shrubs cover and of organic layer thickness.
M. Anisul Islam - One of the best experts on this subject based on the ideXlab platform.
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Ecophysiological adaptations of Black Spruce ( Picea mariana ) and tamarack ( Larix laricina ) seedlings to flooding
Trees-structure and Function, 2003Co-Authors: M. Anisul Islam, S. Ellen MacdonaldAbstract:Black Spruce (Picea mariana (Mill.) B.S.P.) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in boreal peatlands. The effects of 34 days of flooding on morphological and physiolog- ical responses were investigated in the greenhouse for Black Spruce and tamarack seedlings in their second growing season (18 months old). Flooding resulted in reduced root hydraulic conductance, net assimilation rate and stomatal conductance and increased needle electro- lyte leakage in both species. Flooded tamarack seedlings maintained a higher net assimilation rate and stomatal conductance compared to flooded Black Spruce. Flooded tamarack seedlings were also able to maintain higher root hydraulic conductance compared to flooded Black Spruce seedlings at a comparable time period of flooding. Root respiration declined in both species under flooding. Sugar concentration increased in shoots while decreasing in roots in both species under flooding. Needles of flooded Black Spruce appeared necrotic and electrolyte leakage increased over time with flooding and remained signif- icantly higher than in flooded tamarack seedlings. No visible damage symptoms were observed in flooded tamarack seedlings. Flooded tamarack seedlings devel- oped adventitious roots beginning 16 days after the start of flooding treatment. Adventitious roots exhibited significantly higher root hydraulic conductivity than similarly sized flooded tamarack roots. Flooded Black Spruce lacked any such morphological adaptation. These results suggest that tamarack is better able to adjust both morphologically and physiologically to prolonged soil flooding than Black Spruce seedlings.
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Responses of Black Spruce (Picea mariana) and tamarack (Larix laricina) to flooding and ethylene
Tree Physiology, 2003Co-Authors: M. Anisul Islam, S. Ellen Macdonald, Janusz J. ZwiazekAbstract:Black Spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in the boreal peatlands of Alberta, Canada, where low nutrient availability, low soil temperature and a high water table limit their growth. Effects of flooding for 28 days on morphological and physiological responses were investigated in greenhouse-grown Black Spruce and tamarack seedlings in a growth chamber. Flooding reduced root hydraulic conductance, net assimilation rate and stomatal conductance, and increased water-use efficiency (WUE) and needle electrolyte leakage in both species. Although flooded Black Spruce seedlings maintained higher net assimilation rates and stomatal conductance than flooded tamarack seedlings, flooded tamarack seedlings were able to maintain higher root hydraulic conductance than flooded Black Spruce seedlings. Needles of flooded Black Spruce developed tip necrosis and electrolyte leakage after 14 days of flooding, and these symptoms were subsequently more prominent than in needles of flooded tamarack seedlings. Flooded tamarack seedlings exhibited no visible injury symptoms and developed hypertrophied lenticels at their stem base. Application of exogenous ethylene resulted in a significant reduction in net assimilation, stomatal conductance and root respiration, whereas root hydraulic conductivity increased in both species. Thus, although flooded Black Spruce seedlings maintained a higher stomatal conductance and net assimilation rate than tamarack seedlings, Black Spruce did not cope with the deleterious effects of prolonged soil flooding and exogenous ethylene as well as tamarack.
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Responses of Black Spruce (Picea mariana) and tamarack (Larix laricina) to flooding and ethylene
Tree Physiology, 2003Co-Authors: M. Anisul Islam, S. Ellen Macdonald, Janusz J. ZwiazekAbstract:Black Spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) are the predominant tree species in the boreal peatlands of Alberta, Canada, where low nutrient availability, low soil temperature and a high water table limit their growth. Effects of flooding for 28 days on morphological and physiological responses were investigated in greenhouse-grown Black Spruce and tamarack seedlings in a growth chamber. Flooding reduced root hydraulic conductance, net assimilation rate and stomatal conductance, and increased water-use efficiency (WUE) and needle electrolyte leakage in both species. Although flooded Black Spruce seedlings maintained higher net assimilation rates and stomatal conductance than flooded tamarack seedlings, flooded tamarack seedlings were able to maintain higher root hydraulic conductance than flooded Black Spruce seedlings. Needles of flooded Black Spruce developed tip necrosis and electrolyte leakage after 14 days of flooding, and these symptoms were subsequently more prominent than in needles of flooded tamarack seedlings. Flooded tamarack seedlings exhibited no visible injury symptoms and developed hypertrophied lenticels at their stem base. Application of exogenous ethylene resulted in a significant reduction in net assimilation, stomatal conductance and root respiration, whereas root hydraulic conductivity increased in both species. Thus, although flooded Black Spruce seedlings maintained a higher stomatal conductance and net assimilation rate than tamarack seedlings, Black Spruce did not cope with the deleterious effects of prolonged soil flooding and exogenous ethylene as well as tamarack.