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.
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 |
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.
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 |
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.