Guy R. Larocque

• Ph.D.
• Researcher at Natural Resources Canada

The concepts of resilience and stability are pivotal for understanding the dynamics of ecosystems and their ability to keep their ecological integrity in a changing world. As forest ecosystems are dynamic and their stability and integrity cannot be determined using a single point in time, a range of natural variability should be examined. Therefore...

The effect of climate change on forest dynamics is likely to increase in importance in the forthcoming decades. For this reason, it is essential to predict the extent to which changes in temperature, precipitation, and atmospheric CO2 might affect the development of forest ecosystems and successional pathways. The gap model ZELIG-CFS was used to si...

On mine waste rock slopes, trees with inadequate root development could be prone to uprooting. The anchorage of trees is mainly determined by the architecture of the root systems that drive their mechanical interactions with the soil. The objective of this study was to evaluate the effects of soil quality and of different planting materials on the...

The maintenance of the large soil organic carbon (SOC) stocks of the boreal forest under climate change is a matter of concern. In this study, major soil carbon pools and fluxes were assessed in 22 closed-canopy forests located along an elevation and latitudinal climatic gradient expanding 4 ∘C in mean annual temperature (MAT) for two important bor...

The development of simulation models of the dynamics of forest ecosystems has been an active area of research [...]

Environmental concerns and economic pressures on forest ecosystems have led to the development of sustainable forest management practices. As a consequence, forest managers must evaluate the long-term effects of their management decisions on potential forest successional pathways. As changes in forest ecosystems occur very slowly, simulation models...

Le document est disponible à https://scf.rncan.gc.ca/publications?id=40410&lang=fr_CA Le défi pour les forestiers consiste à trouver le bon espacement des arbres afin d’optimiser l’utilisation des ressources du site pour la productivité et la santé du peuplement. Un dispositif expérimental dans des plantations de pins rouges de 60 ans montre que l’...

The document is available at https://cfs.nrcan.gc.ca/publications?id=40411&lang=en_CA The challenge for foresters in managing Red Pine lies in finding the right tree spacing to optimize the use of site resources for stand productivity and health. An experiment in 60 year-old Red Pine plantations shows that thinning allowed for the harvest of fib...

To provide essential knowledge for the development of woodland caribou recovery plans, the Canadian Forest Service initiated an integrative research project in collaboration with the Pessamit Innu community (QC North Shore). The first objective is to mobilize science and indigenous knowledge and perspectives to inform the North Shore caribou recove...

In the past two decades, forest management has undergone major paradigm shifts that are challenging the current forest modelling architecture. New silvicultural systems, guidelines for natural disturbance emulation, a desire to enhance structural complexity, major advances in successional theory, and climate change have all highlighted the limitati...

We report on a 60-year-old red pine (Pinus resinosa Aiton) spacing trial experiment located in Ontario, Canada, that included the combinations between six initial spacings (from 1.2 to 3.0 m) and the presence or absence of a commercial thinning (CT) regime, as well as their impacts on quadratic mean diameter (QMD) and stand volume yield. The CT reg...

The Forest Resources Inventory provides the base layer to support decision-making for a variety of stakeholders in Ontario, Canada. The inventory is used to identify areas of high economic potential, endangered species habitat, and recreational opportunities. As technology evolves, the inventory creation process has changed. From fully manual effor...

Increasing the production of wood fibre from conifer species such as white spruce (Picea glauca (Moench) Voss) is one of many challenges in the management of boreal mixedwood forests. The effects of various competition measures on relative growth and relative growth rate variables were calculated for individual white spruce subject trees. Correlati...

Root development is important to ensure tree survival in conditions of water stress. Despite their long-recognized role, little attention has been given to their development on waste rock slopes subject to rapid drainage. This study was conducted in an open-pit gold mine in a boreal forest. Its main objective was to establish a plantation design wi...

We developed a model of hardwood tree colonization in forest patches. We began with a basic model of species’ recruitment density calculated as a function of seed production and juvenile survivorship. Survivorship probability was expressed as a function of seed size, using seed-sowing data for a wide variety of species. To account for dispersal, we...

Leaf photosynthetic characteristics could be determinant factors to identify the most productive clones of hybrid poplars (Populus spp.) and willows (Salix spp.). Photosynthetic acclimation of hybrid poplars and willows was studied under greenhouse conditions. Seven Populus and five Salix clones were grown for 3 months at three spacings [20 × 20, 3...

We developed allometric equations for small-diameter woody species growing on mixed forest marginal lands, which are potential sources of biomass for bioenergy. Eleven species of trees and shrubs were sampled from a site located in eastern Canada. Equations derived in this study generally performed better than equations from the literature. Also, f...

Caribbean tropical forests are subject to hurricane disturbances of great variability. In addition to natural storm incongruity, climate change can alter storm formation, duration, frequency, and intensity. This model-based investigation assessed the impacts of multiple storms of different intensities and occurrence frequencies on the long-term dyn...

Earth surface systems are controlled by a combination of global and local factors, which cannot be understood without accounting for both the local and global components. The system dynamics cannot be recovered from the global or local controls alone. Ground forest inventory is able to accurately estimate forest carbon stocks in sample plots, but t...

Forests are valued not only for their economic potential, but also for the biodiversity they contain, the ecological services they provide, and the recreational, cultural, and spiritual opportunities they provide. The Ecological Forest Management Handbook provides a comprehensive summary of interrelated topics in the field, including management con...

Forest biodiversity refers to the variability among all forest life forms (trees, plants, animals, fungi and micro-organisms) from genetics to species and ecosystems and their associated ecological processes. Conserving forest biodiversity is a fundamental goal of sustainable forestry. Therefore, governments, non-government organizations (NGOs), ac...

Earth surface systems are controlled by a combination of global and local factors, which cannot be understood without accounting for both the local and global components. The system dynamics cannot be recovered from the global or local controls alone. Ground forest inventory is able to accurately estimate forest carbon stocks at sample plots, but t...

The influence of forest ecology and strategic planning has increased in importance to support the management of mixed-species forests to enhance biodiversity. However, little is known about competitive and facilitative interactions between trees and species in mixed fir–beech–spruce forests, mostly because of a lack of long-term experimental resear...

Ecological modelling is increasing in importance to facilitate the development of sustainable management planning of terrestrial ecosystems and integrate social and economic objectives. As models have become more complex and include many state variables, modelling software platforms have been developed to support development projects. However, few...

Throughout much of the northern temperate and boreal forests of Canada, intensifying silviculture to enhance fibre production is of increasing interest. However, some oppose the application of intensive silviculture citing possible negative effects on biodiversity. Using fifth-year post-harvest data from the NEBIE Plot Network in Ontario, Canada, w...

Carbon (C) content in several forest ecosystem pools, including trees, understory species, downed logs, litter, soil organic and mineral layers, and fine roots, and tree growth were compared in balsam fir (Abies balsamea) and black spruce (Picea mariana) ecosystems located along a climatic gradient in eastern Canada spanning regions that differed b...

The variation in nitrogen, insoluble and soluble proteins, and chlorophyll concentrations (mg·g-1) and contents per unit leaf area (mg·cm-2) as a function of specific leaf area (SLA) was examined in leaves sampled at the bottom, middle, and upper sections of the crowns of balsam fir (Abies balsamea) and black spruce (Picea mariana) trees located al...

The purpose of this investigation was to examine the effects of species composition and crown section on within-crown foliage distribution and the relationship of basal area growth rate to amount of foliage on young white spruce (Picea glauca) growing in pure composition and in mixture with trembling aspen (Populus tremuloides). Branch and needle b...

Throughout much of the northern temperate and boreal forests of Canada, intensifying silviculture to enhance fibre production is of increasing interest. However, some oppose the application of intensive silviculture, citing possible negative effects on biodiversity. Using fifth-year post-harvest data from the NEBIE Plot Network in Ontario, Canada,...

Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamif-era x trichocarpa (PBT) and P. maximowiczii x balsamifera (PMB), one...

Climate change and its potential effects on ecosystems justify the need to implement forest management strategies that increase carbon (C) sequestration. A process-based model, TRIPLEX-Management, was used to investigate how to increase C sequestration within managed jack pine (Pinus banksiana Lamb.) forests. The simulations included a constant cli...

There is a growing interest in fast-growing hybrid poplar and willow plantations in Canada. This interest can be explained both by the rapid growth rate and high yield potential of this type of production system. However, their establishment and maintenance require considerable investments. Research efforts on productivity comparisons between diffe...

Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamif-era x trichocarpa (PBT) and P. maximowiczii x balsamifera (PMB), one...

Ecological modelling can be considered as a significant research activity in the majority of scientific disciplines related to natural resources. Models have been developed for nearly all types of both terrestrial and aquatic ecosystems and for several animal populations. As many models are available, it is tempting to believe that there are no mor...

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth...

A model that accurately evaluates changes in forest productivity and carbon (C) stocks in response to climate change and forest management will permit us to assess the impact of global changes. The goal of this study is to forecast potential effects of climate change and clearcuts on C dynamics of boreal trembling aspen (Populus tremuloides Michx.)...

The objective of the study was to assess the responsiveness of the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) to management scenarios that included three rotation lengths (50, 100 and 250 years) under harvest and fire disturbances in six forest types (poplar deep soil, black spruce deep soil, jack pine deep and shallow soils, hard...

Drought-induced tree mortality, which rapidly alters forest ecosystem composition, structure, and function, as well as the feedbacks between the biosphere and climate, has occurred worldwide over the past few decades, and is expected to increase pervasively as climate change progresses. The objectives of this review are to (1) highlight the likely...

Intra-clonal competition was studied in young hybrid poplar plantations to assess the effects of spacing on growth, biomass production and allocation, and morpho-logical characteristics of above-and below-ground tree parts. Three spacings were used as whole-plots (1 9 1 m, 3 9 3 m and 5 9 5 m), with two hybrid poplar clones as subplots (BT747, Popu...

The development of ecological modelling on global level since the middle of the 19th century is first reviewed, including application of statistical analysis, introduction of logistic curve, earth surface modeling, systems ecology, computer-oriented mathematical models and spatially explicit models. Finally, we discuss problems existing in ecologic...

The eleven symposia organized for the 2009 conference of the International Society for Ecological Modelling (ISEM 2009) held in Quebec City, Canada, October 6–9, 2009, included facilitated discussion sessions following formal presentations. Each symposium focused on a specific subject, and all the subjects could be classified into three broad categ...

Photosynthesis is the most important process driving productivity, and its acclimation to intraclonal competition is not well understood in hybrid poplars. The aim of this study was to examine the physiological response of the crown of two hybrid poplar clones, BT747215 (Populus balsamifera L. × Populus trichocarpa Torr. & A. Gray) and MB915319 (Po...

In order to simulate forest growth response to pre-commercial thinning (PCT), TRIPLEX1.0 – a process-based model designed to predict forest growth as well as carbon (C) and nitrogen (N) dynamics – was modified and improved to also simulate managed forest ecosystem thinning practices. A three-parameter Weibull distribution model was integrated to si...

The removal of corn stover or production of herbaceous crops such as switchgrass (Panicum virgatum) or big bluestem (Andropogon gerardii) as feedstocks for bioenergy purposes has been shown to have significant benefits from an energy and climate change perspective. There is potential, however, to adversely impact water and soil quality, especially...

When the development of gap models began about three decades ago, they became a new category of forest productivity models. Compared with traditional growth and yield models, which aim at deriving empirical relationships that best fit data, gap models use semi-theoretical relationships to simulate biotic and abiotic processes in forest stands, incl...

The objective was to analyse how differences in the initial proportions of tree species and site fertility affect carbon sequestration in living biomass and soil. We used the individual-based simulation model EFIMOD, which is able to simulate spatially explicit competition between trees for light and nutrients. Simulations were carried out for thre...

• Introduction Clay soils are typically rich in nutrients but are often compact and hard during summer increasing planting shock by limiting root development. Recycling farm manure in hybrid poplar plantations may offer additional benefits to mineral fertilizer as organic amendment can create better conditions for the early development of roots in...

The predictions from most forest ecosystem models originate from deterministic simulations. However, few evaluation exercises for model outputs are performed by either model developers or users. This issue has important consequences for decision makers using these models to develop natural resource management policies, as they cannot evaluate the e...

Poplars are one of the woody plants that are very sensitive to water stress, which may reduce the productivity of fast-growing plantations. Poplars can exhibit several drought tolerance strategies that may impact productivity differently. Trees from two improved hybrids, Populus balsamifera × Populus trichocarpa Torr. & Gray (clone B × T) and P. ba...

The long-term effects of high-intensity diameter-limit cuttings conducted in the winter and summer of the 1940s and 1950s on the dynamics of softwood and mixedwood stands in southeastern Quebec were compared. Changes in composition and stand structure over a 50 year period were studied using 18 permanent sample plots located in the Lac-Métis Seigne...

We demonstrate that sugar maple (Acersaccharum Marsh.), yellow birch (Betulaalleghaniensis Britton), and beech (Fagusgrandifolia Ehrh.) compete for solar radiation against other woody species (noncommercial) and herbaceous species, following clear-cutting. The experiment was carried out at the Duchesnay Forest Station (Quebec, Canada) in a sugar ma...

The crown development of red pine (Pinusresinosa Ait.) plantations originating from different initial spacings was studied between 13 and 33 years of age. First, the effect of spacing on models used to predict crown width and crown ratio from diameter at breast height (DBH) and height was examined. Models for trees of different ages that included a...

The development of red pine (Pinusresinosa Ait.) stands originating under different initial spacings was examined using three measures of growth efficiency that are similar in concept to relative growth rate: diameter at breast height (DBH) increment/crown width, DBH increment/crown projection, and DBH increment/foliage biomass. These three measure...

Similar to other boreal regions of Canada, northwestern Quebec has abundant lands available for the establishment of high-productivity plantations. However, few genetically improved species have been tested for this region. Three sites were planted with five hybrid poplar clones; 19 families of white spruce (Picea glauca [Moench] Voss) of southern...

Forest productivity models are increasingly being used for the computation of allowable cuts and forest management decision-making in Quebec. A workshop was organized in the spring of 2008 to bring together modellers, managers, users and administrators to provide a forum for the exchange of views and opinions on the challenges and future perspectiv...

Forest productivity models are increasingly being used for the computation of allowable cuts and forest management decision-making in Quebec. A workshop was organized in the spring of 2008 to bring together modellers, managers, users and administrators to provide a forum for the exchange of views and opinions on the challenges and future perspectiv...

Forest productivity models are increasingly being used for the computation of allowable cuts and forest management decision-making in Quebec. A workshop was organized in the spring of 2008 to bring together modellers, managers, users and administrators to provide a forum for the exchange of views and opinions on the challenges and future perspectiv...

With common concern surrounding the impact of increased atmospheric CO2 on global climate change, the role of forest management (i.e. thinning) on carbon sequestration is growing as a hotspot in the post Kyoto period. However, the combination strategies between forest management and carbon management are less established. Jack pine is one of the mo...

The impact of winter harvesting on regeneration 50 years after an experimental diameter-limit cutting was examined in mixed deciduous–coniferous ecosystems of southern Quebec, Canada. The study was conducted in La Mauricie National Park, Quebec, Canada. Regeneration data in two balsam fir (Abies balsamea (L.) Mill.), red spruce (Picea rubens Sarg.)...

Many process-based models of carbon (C) and nitrogen (N) cycles have been developed for northern forest ecosystems. These models are widely used to evaluate the long-term decisions in forest management dealing with effects like particulate pollution, productivity and climate change. Regarding climate change, one of the key questions that have sensi...

We present a case study approach to assessing the sensitivity of the dead organic matter sub-module of the operational-scale version of the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) to variation in model parameters controlling inputs to and throughput in this module. Parameters examined included those controlling biomass growth a...

Few process-based models of the carbon (C) cycle of forest ecosystems integrate uncertainty analysis into their predictions. There are two explanations as to why uncertainty estimates in the predictions of these models have seldom been provided. First, as the development of forest ecosystem process-based models has begun only recently, research eff...

The forest vegetation simulator (FVS) model was calibrated for use in Ontario, Canada, to predict the growth of forest stands. Using data from permanent sample plots originating from different regions of Ontario, new models were derived for dbh growth rate, survival rate, stem height and species group density index for large trees and height and db...

The gap model ZELIG was validated for red spruce–balsam fir–yellow birch and yellow birch–sugar maple–balsam fir forest types in southern Quebec, Canada. Long-term historical data originating from the Lake Edward Experimental Forest, La Mauricie National Park, were used. The effect of the variation in plot size, representing the space within which...

The objectives of this study were to predict the survival probability of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britton) affected by dieback and to evaluate the critical threshold beyond which mortality caused by dieback is inevitable. Mortality and dieback growth rate of all the trees in 133 sample plots locate...

The sensitivity of soil organic matter decomposition to temperature change is critical tothe global carbon balance and to whether soils will respond with positive feedback to climate change. Forest cover determines litter composition, which controls to a large extent soil organic matter quality and its sensitivity to temperature. The effect of temp...

The predictive capacity of process-based models on the carbon (C) cycle in forest ecosystems is limited by the lack of knowledge on the processes involved. Thus, a better understanding of the C cycle may contribute to the development of process-based models that better represent the processes in C cycle models. A new soil C model was developed to p...

Many process-based models on carbon (C) and nitrogen (N) cycles have been developed for northern forest ecosystems. These models are widely used to evaluate the long-term decisions in forest management dealing with effects like particulate pollution, productivity and climate change. Regarding climate change, one of the key questions that have sensi...

The Lake States variant of the FVS (Forest Vegetation Simulator) model (LS-FVS), also known as the LS-TWIGS variant of FVS, was validated for black spruce (Picea mariana (Mill.) BSP), white spruce (Picea glauca (Moench) Voss), jack pine (Pinus banksiana Lamb.) and trembling aspen (Populus tremuloides Michx.) forests in northern Ontario. Individual-...

In the early 1980s, a sharp increase in dieback of sugar maple (Acer saccharum Marsh.) was reported across large areas of the northeastern American continent. Despite numerous studies, there are conflicting interpretations as to the causes of dieback that can be linked to uncertainties as to when the occurrence of the visual symptoms appeared. Thre...