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Trees growing in urban environments are often impacted by maintenance or construction work involving the cutting of roots. Tree protection zones have been proposed to avoid critical damage to the tree. However, despite incorporating quantitative information, they heavily rely on expert judgement that remains to be validated. In a study conducted across six parks in Quebec City, Canada, two commonly found tree species, Acer platanoides L. and Tilia cordata Mill., presumed to be different in terms of vulnerability to root damage, were subjected to a range of trenching treatments. The trees were between 23 and 40 cm diameter at breast height (DBH). A safety factor was calculated relating the turning moment the tree can withstand to the turning moment imposed by high winds likely to occur. The safety factor against uprooting was assessed for each tree before and after root trenching using a non-destructive pulling approach. The effects of tree species, distance to the trench, and their combined interaction were tested on tree stability. The relationship between tree stability and soil texture, tree characteristics, and the number of damaged roots were also tested. Safety factors were initially variable, ranging from 0.5 to 4.5. T. cordata safety factors were lower than those of A. platanoides and influenced by soil texture. Trenching treatments had no effect on the safety factor, even when two perpendicular trenches were dug at 1 m from the stem. No index of the amount of root damaged was significantly related to the safety factor. Root trenching treatments that encroached closer to the tree trunk than the recommended tree protection zones did not affect the stability of both species. Nevertheless, it is essential to recognize that other ecophysiological processes might still be influenced, and long-term monitoring is crucial. Both should be taken into account when determining these zones. [ABSTRACT FROM AUTHOR]

Process-based forest growth models with spatially explicit representation are relevant tools to investigate innovative silviculture practices and/or climate change effects because they are based on key ecophysiological processes and account for the effects of local competition for resources on tree growth. Such models are rare and are often calibrated for a very limited number of species and rarely for mixed and/or uneven-aged stands, and none are suitable for the temperate forests of Québec. The aim of this study was to calibrate and evaluate HETEROFOR (HETEROgeneous FORest), a process-based and spatially explicit model based on resource sharing, for 23 functionally diverse tree species in forest stands with contrasting species compositions and environmental conditions in southern Quebec. Using data from the forest inventory of Quebec, we evaluated the ability of HETEROFOR to predict the short-term growth (5–16 years) of these species at the tree and stand levels and the long-term dynamics (120 years) of red and sugar maple stands. The comparison between the prediction quality of the calibration and evaluation datasets showed the robustness of the model performance in predicting individual-tree growth. The model reproduced correctly the individual basal area increment (BAI) of the validation dataset, with a mean Pearson's correlation coefficient of 0.56 and a mean bias of 18 %. Our results also highlighted that considering tree position is of importance for predicting individual-tree growth most accurately in complex stands with both vertically and horizontally heterogeneous structures. The model also showed a good ability to reproduce BAI at the stand level, both for monospecific (bias of - 3.7 %; Pearson's r=0.55) and multi-species stands (bias of - 9.1 %; Pearson's r=0.62). Long-term simulations of red maple and sugar maple showed that HETEROFOR was able to accurately predict the growth (basal area and height) and mortality processes from the seedling stage to the mature stand. Our results suggest that HETEROFOR is a reliable option to simulate forest growth in southern Quebec and to test new forestry practices under future climate scenarios. [ABSTRACT FROM AUTHOR]

Ongoing rapid climatic changes are expected to modify the structure, composition, and functioning of forest ecosystems. Studying the influence of such changes on biogeochemical processes is thus crucial for a fuller understanding of forest response to climate change. In a temperate forest of Quebec, Canada, we emulated climate change by warming the acidic, nutrient-poor, and dry soils of two mixedwoods by 3 to 4 °C using heating cables. Leaf-litter mass loss of the local red maple, sugar maple, large-tooth aspen, and American beech were monitored to assess the ability of these tree species to condition boreal soils in the context of their northward migration under climate change. We hypothesized that decomposition rates of all leaf-litter types would be decreased equally by warming due to a drying effect of the soil and its surface, which is detrimental to microbial biomass and activity. Our results suggest differences in decomposition rates between tree species as follows: sugar maple > red maple ≥ American beech = large-tooth aspen. There was no indication of a slower turnover in these marginal soils compared to other studies conducted on typical hardwood soils. Moreover, no difference in litter mass loss was detected between treatments, likely due to a drying effect of the soil warming treatment. Results imply that climate change has a marginal influence on leaf-litter dynamics of temperate tree species on soils that are typical of the boreal forest. However, some variables that could play an important role on litter decomposition in the context of climate change were not measured (e.g., plant phenology, understory composition and density, microbes) and thus, uncertainties remain. The soil drying effect by warming also needs to be further documented and modeled. The study year was characterized by significant periods of water stress but was not considered an exceptional year in that regard. It would be relevant to test for leaf-litter dynamics during dry and wet summers and verify again our initial hypothesis of decreased leaf-litter decomposition rates due to soil warming/drying. [ABSTRACT FROM AUTHOR]

Global warming is affecting plant phenology, with potential consequences on the dynamics of growth reactivation of sugar maple and the timings of maple syrup production. In this study, we assess the temperatures inducing the daily reactivation or cessation of sap production. We selected 19 sugarbushes across Quebec, Canada, using a tapping method associated with the tubing system, we recorded the daily timings of onset and ending of sap production during winter and spring 2018, and we associated the hourly temperatures at each site. Sap production occurred from mid-February to the end of April, starting on average between 10 and 11 AM, and ending from 6 to 8 PM. We observed a seasonal pattern in the onset and ending of sap production during spring, with the onset showing a greater change than the ending. Onset and ending of sap production occurred mostly under temperatures ranging between –2 and 2 °C. The production of sap in maple is closely related to circadian freeze–thaw cycles and occurs under nighttime and daytime temperatures fluctuating below and above 0 °C. The daily lengthening of the duration of sap production mirrors the changes in the timings of freeze and thaw events and can be explained by the physical properties of the water and the physiological processes occurring during growth reactivation. The ongoing warming will result in earlier and warmer springs, which may anticipate the cycles of freeze and thaw and advance sap production in sugar maple. [ABSTRACT FROM AUTHOR]

Process-based forest growth models with spatially explicit representation are a relevant tool to investigate innovative silviculture practices and/or climate change effects because they are based on key ecophysiological processes and account for the effects of local competition for resources on tree growth. Such models are rare, often calibrated for a very limited number of species and rarely in mixed and/or uneven-aged stands, and none are suitable for the temperate forests of Québec. The aim of this study was to calibrate and evaluate HETEROFOR, a process-based and spatially explicit model based on resource sharing, for 23 functionally diverse tree species in forest stands with contrasting species compositions and environmental conditions in southern Québec. Using data from the forest inventory of Québec, we evaluated the ability of HETEROFOR to predict the short-term growth (5-16 years) of these species at the tree and stand levels, and the long-term dynamics (120 years) of red and sugar maple stands. The comparison between the prediction quality for the calibration and evaluation datasets showed the robustness of the model performance in predicting individual tree growth. The model reproduced correctly individual basal area increment (BAI) of the validation dataset with a mean Pearson’s correlation coefficient of 0.56 and a mean bias of 18%. Our results also highlighted that considering tree position is of importance for predicting individual tree growth most accurately in complex stands with both vertical and horizontal heterogeneous structure. The model also showed a good ability to reproduce BAI at the stand level, both for monospecific (bias of -3.7%, Pearson’s r = 0.55) and multi-species stands (bias of -9.1%, Pearson’s r = 0.62). Long-term simulations of red maple and sugar maple showed that HETEROFOR was able to accurately predict the growth (basal area and height) and mortality processes from the seedling stage to the mature stand. Our results suggest that HETEROFOR is a reliable option to simulate forest growth in southern Québec and test new forestry practices under future climate scenarios. [ABSTRACT FROM AUTHOR]

Some ombrotrophic peatlands in temperate regions have been characterized by a process of rapid densification of their forest cover for several decades. This phenomenon is particularly marked in southern Québec (Canada), where a number of peatlands now contain mixed forest stands. The present study aimed to document the woody encroachment dynamics of a peatland colonized by Larix laricina (Du Roi) K. Koch and Acer rubrum L. The specific objectives were to characterize the contemporary dynamics of the forest cover through analysis of dendrometric, dendrochronological, and aerial photographs, and to reconstruct the evolution of tree species present in situ since the peatland's origin through botanical identification of ligneous remains collected in excavations of the peat as well as macrofossil analysis of a sedimentary core. The vegetation cover underwent rapid transformation beginning in the 1970s, first by the densification of L. laricina, followed by the expansion of A. rubrum. This transformation followed several millennia during which the peatland continuously presented a shrub-dominated cover with a few scattered coniferous trees. The rapid expansion of a mixed forest cover is a unique event in the peatland's history. Acer rubrum progressively replaced L. laricina and, in the more or less long-term, should become the dominant species. [ABSTRACT FROM AUTHOR]

We used a high-resolution lacustrine pollen record from Étang Fer-de-Lance (45°21′21.9′N, 72°13′35.3′W), southeastern Québec, Canada, together with microcharcoal, to infer forest dynamics and human impacts over the past 2300 years. The lake is located in the eastern sugar maple-basswood forest domain of the Northern Temperate Forest of eastern North America. We found that the pollen percentages and influxes of Fagus grandifolia (American beech) and Tsuga canadensis (eastern hemlock) significantly declined over the past 700 years. Over the last millennium, the pollen percentages and influxes of the Picea species (P. glauca, P. mariana, P. rubens) (white, black, and red spruce), and Pinus strobus (eastern white pine) significantly increased. We showed that these shifts in forest composition are being driven by changes in regional climate. In addition to the pollen percentage changes, the Medieval Climate Anomaly (AD 800–1300) appeared as increased pollen influxes and the Dark Ages Cold Period (AD 400–700) and Little Ice Age (AD 1400–1800) appeared as decreased pollen influxes. The signal for human modification of the landscape first appeared at ~AD 1550–1650 as increases in Ambrosia (ragweed) and Poaceae (grasses) from possible Indigenous agriculture. The signal of European settler landscape modification appeared at ~AD 1770 as the beginning of a steep, "classic" Ambrosia rise. It intensified over the subsequent 250 years as further increases in non-arboreal pollen taxa and early successional Acer (maple) species. Microcharcoal analysis showed that fire was a re-occurring event in the sugar maple-basswood domain, but had little impact on forest composition. [ABSTRACT FROM AUTHOR]

With steep climatic gradients over short distances, montane ecosystems provide exceptional opportunities to study ecological responses to climate and other environmental changes. Here we present a summary and synthesis of 10 years of research on this theme in a protected area in southern Québec, Canada (Parc National du Mont Mégantic), with ecological conditions closely similar to the northern Appalachians. During the ∼150 years since European settlement, anthropogenic disturbance has reduced the abundance of certain taxa (e.g., Picea [spruce]), while favoring other taxa that thrive during succession (e.g., Betula [birch], Acer [maple]). In more recent decades, climate warming (∼0.21 °C per decade) appears to have prompted upward elevational range shifts for many plant species, although such responses lag behind changes in climate itself. Experimental studies with seeds and seedlings of Acer saccharum (Sugar Maple) suggest that upward range expansion might be constrained by non-climatic factors such as belowground properties and seed predators, while escape from insect herbivores might actually accelerate range expansion. Similar studies with understory plants have not revealed clear evidence of non-climatic constraints on range limits, although some preliminary data presented here suggest a possible role of a lack of microsites with rich, moist soil at high elevation. Current studies focus on the lower elevational range limits of species restricted to mountaintops, such as certain lichens. Vegetation and flowering phenology are also sensitive to climate, and we have found that earlier springs are associated with decreased potential gene flow across populations at different elevations; ongoing studies will determine how differential sensitivity of herbs vs. trees might influence the duration of a high light period in spring in the understory. Overall, we have found clear signals of plant responses to long-term anthropogenic disturbances and recent climatic warming, but considerable uncertainty remains about how climatic and non-climatic factors will interact to determine the future of this montane ecosystem. [ABSTRACT FROM AUTHOR]

Understanding the influence of climatic variation on forest dynamics is of great ecological and economic interest, and is essential to prescribe silvicultural interventions that will facilitate ecosystem acclimation to global change. However, the retrospective identification of climatic events responsible for the inter‐annual variation of tree growth is challenging, notably because both their duration and their subsequent effects can be highly variable in time. In this study, we aimed to (1) quantify empirically the effect of climatic stress events on the short‐ and long‐term growth dynamics of sugar maple trees; (2) compare the effects of different types of climatic events, that is, drought and thaw–freeze; and (3) compare the effects of climatic stress events to those of traditional monthly level climate metrics. To achieve this, we paired cross‐dated tree‐ring series to monthly and daily‐level climate metrics over more than 50 yr in two distinct regions of southern Quebec. While the analysis from monthly level metrics first suggested a weak and non‐stationary relationship between climatic conditions and tree growth, the analysis from daily‐level metrics showed that climatic stress events, and more particularly thaw–freeze events, were strongly related to the growth of sugar maple trees. Our results suggest that the synergic influence of cumulative climatic stress events, which was exacerbated by insect outbreaks during the early 1980s, induced an important shift in the growth dynamics of sugar maple and in its response to variation in climatic conditions. These results highlight the potential negative impact of global climate change on our capacity to predict stand productivity accurately, especially if climate‐sensitive growth models are based on projections of future monthly metrics. Because adverse climatic events are expected to increase both in frequency and in severity over the next decades, a general decrease in the growth rate of sugar maple is apprehended in southern Quebec. [ABSTRACT FROM AUTHOR]

Understanding the determinants of reproduction is a central question in evolutionary ecology. In pulsed‐resource environments, the reproduction and population dynamics of seed consumers are driven by pulsed production of seeds by trees or mast‐seeding. In Southern Québec, eastern chipmunks Tamias striatus exclusively reproduce during the summer before and the spring after a mast‐seeding event of American beech. They thus seem to anticipate beech mast by reproducing during early summer, so that juveniles can emerge at the time of maximum beechnut abundance during late summer.However, the cues allowing chipmunks to anticipate beech mast remain unknown, and the existence of the anticipation process itself has been questioned. To tackle those issues, we investigated the links between the nutritional ecology and reproduction of adult chipmunks and compared their spring diet in mast‐ versus post‐mast years.We monitored female reproductive status (N = 446), analysed cheek pouch contents at capture (n = 3,761 captures) and recorded seed production by deciduous trees on three different sites in Mont‐Sutton from 2006 to 2018.Results revealed a systematic shift in chipmunk diet towards red maple seeds in springs preceding a beech mast, with red maple seeds composing more than 77% of chipmunk diet. However, red maple consumption was unrelated to red maple production, but was related to beech seed production in the upcoming fall. We also found that red maple consumption best predicted the proportion of females in summer oestrus.Our results confirm that chipmunks anticipate beech mast‐seeding and highlight a key role of red maple consumption in that anticipation. Results also suggest that red maple seeds may contain nutrients or secondary plant components essential to sustain or trigger the summer reproduction in chipmunks, which allow them to remain synchronized with pulsed productions of both red maple and beech and improve their fitness. [ABSTRACT FROM AUTHOR]

Background. Bacteria, archaea, viruses and fungi live in various plant compartments including leaves and roots. These plant-associated microbial communities have many effects on host fitness and function. Global climate change is impacting plant species distributions, a phenomenon that will affect plant-microbe interactions both directly and indirectly. In order to predict plant responses to global climate change, it will be crucial to improve our understanding of plant-microbe interactions within and at the edge of plant species natural ranges. While microbes affect their hosts, in turn the plant's attributes and the surrounding environment drive the structure and assembly of the microbial communities themselves. However, the patterns and dynamics of these interactions and their causes are poorly understood. Methods. In this study, we quantified the microbial communities of the leaves and roots of seedlings of the deciduous tree species sugar maple (Acer saccharum Marshall) within its natural range and at the species' elevational range limit at Mont-Mégantic, Quebec. Using high-throughput DNA sequencing, we quantified the bacterial and fungal community structure in four plant compartments: the epiphytes and endophytes of leaves and roots. We also quantified endophytic fungal communities in roots. Results. The bacterial and fungal communities of A. saccharum seedlings differ across elevational range limits for all four plant compartments. Distinct microbial communities colonize each compartment, although the microbial communities inside a plant's structure (endophytes) were found to be a subset of the communities found outside the plant's structure (epiphytes). Plant-associated bacterial communities were dominated by the phyla Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes while the main fungal taxa present were Ascomycota. Discussion. We demonstrate that microbial communities associated with sugar maple seedlings at the edge of the species' elevational range differ from those within the natural range. Variation in microbial communities differed among plant components, suggesting the importance of each compartment's exposure to changes in biotic and abiotic conditions in determining variability in community structure. These findings provide a greater understanding of the ecological processes driving the structure and diversity of plant-associated microbial communities within and at the edge of a plant species range, and suggest the potential for biotic interactions between plants and their associated microbiota to influence the dynamics of plant range edge boundaries and responses to global change. [ABSTRACT FROM AUTHOR]

Previous studies have shown in noncalcareous soils that acid deposition may have increased soil leaching of basic cations above the input rate from soil weathering and atmospheric depositions. This phenomenon may have increased soil acidity levels, and, as a consequence, may have reduced the availability of these essential nutrients for forest growth. Fourteen plots of the Forest Ecosystem Research and Monitoring Network in Québec were used to examine the relation between post‐industrial growth trends of sugar maple (Acer saccharum Marsh.) and acid deposition (N and S), stand decline rate, and soil exchangeable nutrient concentrations. Atmospheric N and S deposition and soil exchangeable acidity were positively associated with stand decline rate, and negatively with the average tree basal area increment trend. The growth rate reduction reached on average 17% in declining stands compared with healthy ones. The results showed a significant sugar maple growth rate reduction since 1960 on acid soils. The appearance of the forest decline phenomenon in Québec can be attributed, at least partially, to soil acidification and acid deposition levels. [ABSTRACT FROM AUTHOR]

[Display omitted] • QC of maple syrup is summarized based on physical and chemical properties. • pH and Brix values served as markers for its QC in relation to the collecting season. • Color intensity of different maple grades was proportional to its antioxidant activity. • Several analytical technologies used for maple syrup QC have been outlined. • Principal flavor compounds included phenolics, pyrazines &, carbonyl-based molecules. Maple syrup a natural sweetener is obtained by boiling the sap drained from Acer saccharum L. tree and other maple species. Worldwide, maple syrup is produced only in Northeastern America, primarily in the province of Quebec (Canada), followed by the United States of America. Maple syrup is the most commonly used formula of maple-derived foods due to its economic and nutritional value being a rich source of natural phenolic compounds like acids, flavonoids, stilbenes, coumarins and furan derivatives along with vitamins, amino acids, organic acids, simple sugars as well as complex carbohydrates. This review aims to pinpoint the different analytical approaches applied for the quality control of maple syrup are based on their physical and chemical properties; moreover, the authentication methods and detection of adulteration were also highlighted. Such a review of quality control could be further applied for other syrup types of similar matrix composition (i.e., sugarcane). [ABSTRACT FROM AUTHOR]

• Wood ash application had a positive short-term effect on the growth of mature sugar maple trees. • Wood ash application resulted in a decrease in Ca deficiency and N excess in seedlings and mature sugar maple trees. • Wood ash application had a positive short-term effect on the soil acid-base status. • Wood ash application is a promising practice to restore the productivity of sugar maple stands on acidic soils. Wood ash as soil amendment is increasingly being used globally to counter forest soil acidity, increase base cation availability, especially Ca, and correct foliar nutritional deficiencies/imbalances. Knowledge remains limited regarding the effects of wood ash in temperate hardwood forests dominated by sugar maple and supported by acidic soils with low availability of base cations. The main objective of this study was to determine short-term effects of wood ash application on the soil's acid base-status and nutrient availability, foliar nutrition, and growth of seedlings and mature sugar maple trees. A first experiment was established in 15 stands across southeastern Quebec, which included an unamended control and a 20 Mg ha−1 treatment. A layer of naturally regenerated sugar maple seedlings was present in these stands. A second experiment was conducted on four other sites, which included an unamended control and three ash treatments (5 Mg ha−1, 10 Mg ha−1, 20 Mg ha−1); sugar maple seedlings were then planted at high density (50 × 50 cm). In Experiment 1, ash application resulted in increased pH and concentrations of P, Ca and Mg in the forest floor after 3 years. Only marginal treatment effect was detected in the upper mineral soil, where pH and Ca and Mg concentrations tended to be higher under the ash treatment. Nutritional diagnoses using the DRIS approach revealed that the different ash treatments were associated with a decrease in Ca deficiency and N excess in sugar maple (seedlings and mature trees). Using dendrochronological data from 288 trees, we measured a positive effect of the 20 Mg ha−1 ash treatment on the basal area increment (BAI) of mature sugar maple from the first year after application. Within 3 years following ash application, mean annual BAI of sugar maple in the ash treatment was 20% higher (+1.9 cm2 y−1) than that of the control. The ash treatments exerted no effect on sugar maple seedling growth. Varying wood ash doses had weak effects on seedling nutrition in Experiment 2. Our results indicate that ash application may exert positive short-term effects on the soil acid-base status, foliar nutrition, and diameter growth of mature sugar maple trees. [ABSTRACT FROM AUTHOR]

• Gap model ZELIG-CFS is evaluated using long term inventory and disturbance data. • ZELIG-CFS makes better predictions of common trees when disturbances are simulated. • Deciduous species responsible for observed compositional change are underestimated. • Suggested improvements: integration of regeneration strategies and disturbance risk. The lack of long term independent historical data constitute a major impediment to the further improvement and validation of forest simulation models. In this study, we evaluate the degree to which the gap model ZELIG-CFS realistically predicts the long term stand development of mixed forests in southeastern Quebec when disturbance history is considered. An early 1930 forest inventory and disturbance data were used to evaluate model simulation performance over the 1930–2013 period. ZELIG-CFS well predicted the basal area of balsam fir in simulations with and without disturbances. When disturbances were simulated, the predictions for white spruce and white birch were more realistic than in the simulation without disturbances. At the same time, deciduous species that contributed the most to the compositional changes observed during the 20th century in mixed forests (red maple, sugar maple, and trembling aspen) were systematically underestimated by the model. Several improvement avenues are suggested: (1) A better integration of regeneration strategies of tree species, especially the integration of a probability of vegetative reproduction for sprouting species like red maple, sugar maple, trembling aspen and northern white cedar, (2) Coupling gap models with a stand risk model to better simulate natural and human disturbance probability as a source of exogenous mortality. [ABSTRACT FROM AUTHOR]