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Fortin M.,French National Institute for Agricultural Research | Langevin L.,Direction de la Recherche Forestiere
Annals of Forest Science | Year: 2012

Introduction Deterministic single-tree models are commonly used in forestry. However, there is evidence that stochastic events may interact with the nonlinear mechanisms that underlie forest growth. As a consequence, stochastic and deterministic simulations could yield different results for the same single-tree model and the same initial conditions. This hypothesis was tested in this study. Material and methods We used a single-tree growth model that can be implemented either stochastically or deterministically. Two data sets of 186 and 342 plots each were used for the comparisons. For each plot, the simulations were run on a 100-year period using 10-year growth steps. Three different response variables were compared. Results The results showed that there were differences between the predictions from stochastic and deterministic simulations for some response variables and that randomness alone could not explain these differences. In the case of deterministic simulations, the fact that predictions are reinserted into the model at each growth step is a concern. These predictions are actually random variables and their transformations may result in biased quantities. Forest growth modellers should be aware that deterministic simulations may not correspond to the mathematical expectation of the natural dynamics. © INRA and Springer Science+Business Media B.V 2011.


Moore J.-D.,Direction de la recherche forestiere | Houle D.,Direction de la recherche forestiere | Houle D.,Environment Canada
Forest Ecology and Management | Year: 2013

Ammonium nitrate was added annually at 3- and 10-fold the ambient wet atmospheric deposition rate (8.5kgha-1year-1) during 8years in a base-poor northern hardwood forest of Québec, Canada. Soil chemistry and foliar chemistry, crown dieback and basal area growth of sugar maple (Acer saccharum Marsh.) were measured after 8years of treatments. Despite repeated N additions, N concentrations in all soil layers remained similar between treatments. However, the treatments significantly reduced exchangeable Ca, Mg, Mn and K compared to the untreated plots, at least for one of the top organic soil layers. The most significant and substantial differences were observed for Ca between the control and the high N treatment, with the L and the H layers showing decreases of 29% and 72%, respectively. Foliar Ca and Mn concentrations decreased with increasing levels of N addition, while foliar N increased. Foliar Ca in the high N treatment decreased by 79% compared to the control and reached 0.24%, the lowest foliar Ca concentration ever reported for sugar maple. No significant treatment effects were observed for dieback rate or basal area growth, although mean dieback rate of sugar maple in the high N treatment was 43% higher than in the control. Our results show that increased N deposition, even at relatively low rates, can strongly affect Ca nutrition of sugar maple at sites with low base cation saturation. This raises concerns about the sustainability of sugar maple in acidic, base-poor forest soils. © 2013 Elsevier B.V.


Moore J.-D.,Direction de la recherche forestiere | Ouimet R.,Direction de la recherche forestiere | Bohlen P.J.,University of Central Florida
Soil Biology and Biochemistry | Year: 2013

During the last several decades, colonization of soil by exotic earthworms and their effects on soil properties and biodiversity have been reported in forests of North America. In some northern hardwood stands, acid soils or harsh climate may have prevented earthworm colonization. However, climatic change and the increasing use of liming to restore the vigor of declining sugar maple (Acer saccharum Marsh.) stands, situated on base-poor soils in USA and Canada, could make many of these sites more suitable for earthworm colonization. We tested survival and reproduction of two exotic earthworm species (Lumbricus terrestris and Amynthas hawayanus) in unlimed and limed soils at the northern limit of the northern hardwood forest distribution in Canada. Improving soil parameters of base-poor, acidic soils by liming positively influenced activity, survivability and reproductive output of L.terrestris in this northern hardwood forest. In contrast, the high mortality and low vigor of L.terrestris observed in the unlimed plots show that soils in this area with a pH of 4.3 are not favorable to this species. Our results suggest that A.hawayanus was very active prior to winter at both soil pHs, but was not able to complete its life cycle during one year at this latitude. Both earthworm species significantly reduced organic C and total N, and increased the C/N ratio of the forest floor. Given that forest liming activities are increasing in proximity to human activities, there is high probability that some earthworm species, such as L.terrestris, will invade limed northern hardwood forests in the next decades, with possible consequences for soil organic matter turnover, nutrient cycling and forest biodiversity and dynamics. © 2013 Elsevier Ltd.


Bouchard M.,Direction de la Recherche Forestiere | Boudreault C.,Laval University
Biological Conservation | Year: 2016

For a given species, reducing the extent, connectivity and health status of source populations will diminish the probability of colonizing suitable habitats. In this study, we evaluated if metapopulation size helped predict species presence in suitable habitats, by using boreal understory plants and epiphytic lichens as case studies. We sampled a network of 792 vegetation plots located across a 240,000-km2 section of pristine boreal forests. Landscape-level species abundance (LLSA), a proxy formetapopulation size,was quantified in a 50kmradius surrounding each plot. The effects of local environmental factors and LLSA on species presence were modelled with general linear models (GLMs). Forty-eight vascular plant species and 8 pendulous epiphytic lichens were abundant enough to be considered in the statistical analyses. Habitat variables explained the presence of 30 vascular plants and 4 lichen species to a relatively strong degree (Tjur's R2 N 0.15).Among these species, 16 vascular plants and 4 lichenswere significantly influenced by LLSA, independently of local habitat characteristics. Vascular plant species whose presencewas significantly affected by LLSA did not exhibit particular morphological traits or habitat preferences comparedwith those thatwere not affected. By contrast, the 4 epiphytic lichen species thatwere affected by LLSA were all associated with older forests. No species exhibited obvious metapopulation size thresholds below which the probability of species presence in suitable habitats dropped drastically. In terms of conservation, these results suggest that coarse-filter approaches are probably more robust and easy to implement than species-specific threshold approaches in this kind of ecosystem. © 2016 Elsevier Ltd.


Moore J.-D.,Direction de la recherche forestiere | Ouimet R.,Direction de la recherche forestiere | Duchesne L.,Direction de la recherche forestiere
Forest Ecology and Management | Year: 2012

Dolomitic lime (CaMg(CO 3) 2) was applied in 1994 at rates of 0-50Mgha -1 to sugar maples (SMs) (Acer saccharum Marsh.) in a base-poor and declining northern hardwood stand subjected to a high level of acid deposition in Quebec. The soil chemistry and the SM nutrition, growth, crown vigor, and regeneration status were evaluated 15years after treatment. The soil chemical properties still responded strongly to lime after 15years. Similarly, the foliar Ca and Mg concentrations were still higher for treated trees relative to the control trees. After 15years, the mean crown dieback of trees decreased quadratically with the lime rate, from 39% for the control trees to a value of 1-3% for the lime rates of 5Mgha -1 and higher. Additionally, the stem basal area increment for the limed trees was nearly double that of the unlimed trees in 2009. The lime application was also beneficial to the SM regeneration. The overall SM seedling density increased with the lime rate, being nearly twice as much in the 50Mgha -1 (32 seedlings m -2) compared with the controls (16 seedlings m -2). The proportion of the SM seedlings to all of the other species increased quadratically from 22% in controls to more than 55% in the 5-50Mgha -1 treatments. In contrast, the proportion of competitive species decreased quadratically with the lime rate, including American beech (Fagus grandifolia Ehrh.) for which the proportion in the treated plots (24%) was nearly half the proportion observed in the controls (46%). However, increase in stem density of regeneration and canopy closure in response to lime application limit the development of the regeneration which did not benefit in terms of diameter and height. These results show that a single lime addition has long-term beneficial effects on the soil chemistry and the SM nutrition, vigor, growth, and regeneration in base-poor and declining northern hardwood stands. Moreover, the results confirm that liming is an essential tool to restore the SM representation and health in acidic and base-poor soils. © 2012.


Moore J.-D.,Direction de la recherche forestiere | Ouimet R.,Direction de la recherche forestiere
Forest Ecology and Management | Year: 2014

Sugar maple (Acer saccharum Marsh., hereafter SM) dieback has been of concern in many stands of northeastern North America for decades. In acidic, base-poor forest soils, this phenomenon has often been attributed to calcium (Ca) deficiency. Corrective measures such as dolomitic lime addition (CaMg(CO3)2) have been tested to restore SM vitality in these ecosystems. However, few studies have evaluated the effect of Ca addition alone on SM. Furthermore, liming experiments have showed that the Mg content of lime could induce a nutritional antagonism which hinders potassium (K) uptake. This may have limited the response of SM to dolomitic lime application. To address these issues, two calcium fertilizers with negligible Mg content (CaCO3 and CaSO4·2H2O) were applied at rates of 1, 2 and 4tCaha-1 on SM trees. After 7years, foliar Ca nutrient concentrations of treated trees increased in both Ca treatments, reaching published concentration ranges for healthy SM trees. These increases were greater than those observed after a similar period in two nearby experiments in which CaMg(CO3)2 and CaCO3 were used at comparable or lower doses. Also, no nutrient antagonism was detected in the present study. Tree crown vigor and basal area growth were improved by the Ca treatments, but the magnitude of the growth response for trees treated with the CaCO3 fertilizer was far less than in the other nearby experiment where CaCO3 was also used. This strongly suggests that Mg nutrition is not a limiting factor in this ecosystem. The comparatively lower growth response of trees to Ca treatments in this study is unclear, but better growth conditions at the studied site, compared to the two other nearby experiments, may have played a role in this phenomenon. Long-term monitoring of these experiments seems warranted to clarify these issues. © 2014 Elsevier B.V.


Duchesne L.,Direction de la recherche forestiere | Houle D.,Direction de la recherche forestiere
Forest Ecology and Management | Year: 2011

In the present context of global climate changes and the continuous development of forest management strategies based on the concept of sustainable use, it is important to develop a better understanding of the climatic factors controlling the growth of boreal forests. In this study, we report the results of a five-year field research within which day-to-day balsam fir (Abies balsamea (L.) Mill.) stem diameter variation was measured with dendrometers and examined in relation with various daily climatic variables. A model built with data from three growing seasons that included solar radiation, relative humidity, temperature and precipitation explained 84% of the variance in day-to-day stem diameter variation from June to September. The model has approximately the same predictive capability when validated with independent daily data from two other growing seasons. The model captured both the cumulative increment associated with the irreversible growth and the high frequency variation of day-to-day fluctuations associated to changes in the stem water content. In general, rainy days during which relative humidity was high and solar radiation was low favored stem diameter expansion (growth and swelling) while stem diameter decreased during periods of low relative humidity and high solar radiation. Similar models were obtained when the June-September period was divided into two parts (June-July and August-September) to better represent the period during which most of the cumulative annual stem increment is observed (June-July). Inter-annual variation in stem growth computed from the modeled day-to-day variation in stem diameter was significantly correlated to the inter-annual variation in annual growth determined from tree core measurements over a 10 year period (p=0.023). The model was notably able to capture a particularly poor growing year (2006) presumably due to a short-term heat stress period. Results suggest that the inclusion of daily data in growth-climate models may contribute to improve predictions of the potential tree growth response to climate by identifying particular climatic events that may escape to a classical dendroclimatic approach. © 2011.


Moore J.-D.,Direction de la recherche forestiere
Forest Ecology and Management | Year: 2014

Liming, the application of calcitic materials to soil, is increasingly used in acidic, base-poor sugar maple stands of eastern North America to restore nutritional status and vigor of sugar maple trees. However, few studies have evaluated the effect of base cation addition on other components of these ecosystems. The eastern red-backed salamander (Plethodon cinereus) is one of the most abundant vertebrates in forests of eastern North America, and is commonly used as an indicator of forest disturbances. So, it is important to know how it might be affected by soil liming. This is the first study dealing with the potential direct and short-term effect of liming on amphibians of North America.Lime, in the form of CaCO3 (3Mgha-1), was added at the surface of microcosms containing a low buffered soil and forest floor from a sugar maple stand to evaluate the short-term effect of this treatment on this amphibian species. Two grades of lime were used in this study: finely ground and sandy CaCO3. Finely powdered lime was included to verify if it could clog salamander skin pores, since this could negatively affect health and growth, and consequently induce mortality. The results suggest that, even when applied in finely ground form, direct contact with lime had no short-term effect on the species' health and survival rate. Given this, and the fact that it can be found in a wide range of soil pH conditions, the red-backed salamander is thus unlikely to be affected by the use of liming to restore acidic, base-poor sugar maple bushes. Some old liming trials carried out in forests of eastern North America could be used in the next years to verify the long-term effects of liming on this species. This should help foresters decide whether or not liming treatments are compatible with conservation, ecological and management objectives. © 2014 Elsevier B.V.


Moore J.-D.,Direction de la recherche forestiere | Ouimet R.,Direction de la recherche forestiere
Canadian Journal of Forest Research | Year: 2010

Over the last decades, continuous signs of sugar maple (Acer sacchamm Marsh.) dieback in stands of northeastern North America have promoted the experimentation of corrective measures to restore sugar maple vitality. To verify the hypothesis that K-Mg antagonism may have limited the full response of sugar maple to dolomitic lime application in a previous experiment (CaMg(CO 3) 2, 12% Mg), two Ca fertilizers (CaCO 3 and CaSO 4·2H 2O), having negligible Mg content, were applied at rates of 1, 2, and 4 t Ca·ha 1 on sugar maple trees adjacent to the limed area. After 3 years, most of the foliar nutrient concentrations of treated trees were improved, particularly Ca, for both Ca fertilizers, in line with published ranges for healthy sugar maple trees, except for Mg. Moreover, no persistent nutrient antagonism was observed. The crown dieback rate of treated sugar maple was <5.8% after 3 years, while it reached 12% for the controls. Also, relative basal area growth showed that both Ca sources can improve growth rate. Growth response following Ca treatments was, however, lower than for the former lime experiment after the same period of time. In this context, our results suggest that Mg nutrition could be more important for sugar maple in this ecosystem than initially thought.


Moore J.-D.,Direction de la recherche forestiere | Ouellet M.,Amphibia Nature
Global Change Biology | Year: 2015

The effects of recent climate changes on earth ecosystems are likely among the most important ecological concerns in human history. Good bioindicators are essential to properly assess the magnitude of these changes. In the last decades, studies have suggested that the morph proportion of the eastern red-backed salamander (Plethodon cinereus), one of the most widely distributed and abundant vertebrate species in forests of eastern North America, could be used as a proxy for monitoring climate changes. Based on new discoveries in the northern areas of the species' range and on one of the largest compilation ever made for a vertebrate in North America (236 109 observations compiled from 1880 to 2013 in 1148 localities), we demonstrate however that climatic and geographic variables do not influence the colour morph proportions in P. cinereus populations. Consequently, we show that the use of colour morph proportions of this species do not perform as an indicator of climate change. Our findings indicate that bioindicator paradigms can be significantly challenged by new ecological research and more representative databases. © 2014 John Wiley & Sons Ltd.

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