http://www.sysecol2.ethz.ch/Refs/EntClim/S/Se083.pdf

Modelling natural disturbances in forest ecosystems: a review

Spatiotemporal patterns of mortality in declining balsam fir and spruce stands

Stand production and sustained yield calculations are largely affected by tree mortality, which can be caused by many factors such as competition, insect damage, or climatic events. In the eastern Canadian boreal forest, spruce budworm (Choristoneura fumiferana (Clem.)) defoliation can produce varying levels of mortality in balsam fir (Abies balsamea (L.) Mill.) stands. This mortality was estimated for the entire range of balsam fir in Quebec, Canada, using historical records of insect defoliation and permanent sample plot (PSP) inventories for the 1970-2003 period, which includes the last insect outbreak. A two-step approach was used to model balsam fir mortality at the stand level. The first step predicts the probability that all balsam fir trees within a PSP will survive during a given time interval. The second step quantifies the amount of mortality for PSP observation periods during which mortality actually oc- curred. The whole model shows that spruce budworm defoliation may account for between 6% and 100% of the mer- chantable volume lost due to mortality, depending on outbreak severity. A model evaluation made with an independent data set indicates that the model is unbiased, although the prediction error is relatively large at the stand level but de- creases with increasing prediction horizon. Resume : La production des peuplements et les calculs de possibilite forestiere sont affectes par la mortalite des arbres qui peut etre causee par plusieurs facteurs comme la competition, les dommages par les insectes ou des evenements climatiques. Dans la foret boreale de l'est du Canada, les defoliations causees par la tordeuse des bourgeons de l'epinette (Choristoneura fumiferana (Clem.)) peuvent produire differents niveaux de mortalite dans les peuplements domines par le sapin baumier (Abies balsamea (L.) Mill.). Cette mortalite a ete estimee pour l'ensemble de l'aire de distribution du sapin baumier au Quebec, Canada, en utilisant des releves historiques de defoliation et les inventaires de placettes-echantillons permanentes au cours de la periode 1970-2003, ce qui inclut la derniere epidemie de la tor- deuse des bourgeons de l'epinette. Une approche en deux etapes a ete utilisee pour modeliser la mortalite du sapin baumier a l'echelle du peuplement. La premiere etape sert a prevoir la probabilite que l'ensemble des sapins baumiers d'une placette-echantillon permanente survivent pendant un intervalle de temps donne. La deuxieme etape quantifie la mortalite au cours des periodes d'observation pendant lesquelles une mortalite d'arbre est reellement survenue. Le mo- dele global montre que les defoliations causees par la tordeuse peuvent expliquer de 6 a 100 % du volume marchand perdu par mortalite selon la severite de l'epidemie. Une evaluation du modele faite a l'aide d'un fichier independant de donnees indique que le modele n'est pas biaise. Cependant, l'erreur de prevision est relativement grande a l'echelle du peuplement, mais elle diminue avec l'augmentation de l'horizon de prevision.

http://www.mffp.gouv.qc.ca/publications/forets/connaissances/recherche/Mailly-Daniel/Can-J-For-Res-36-1631-1640.pdf

Stand-level prediction of balsam fir mortality in relation to spruce budworm defoliation

cover point processes in the modern sense of random measures. This chapter also is more technical than the subsequent two on Markov processes. Chapter 4 (on discrete-time countable state Markov processes) is extremely short. At only 32 pages, it is shorter than all those covering a specific type of process, except for Chapter 6 (martingales). I wonder how much the typical student will benefit from the minimal, and delayed, presentation of this topic. In my experience, most students need this material early on, to fully appreciate just what stochastic processes are and what the relevant issues are, before moving on to the more technical processes. The fifth chapter (on continuous-time countable state Markov processes) is the best-developed chapter and contains many more examples than do the other chapters. Birth–death processes and queuing models get substantial coverage, and there is plenty of material here that an instructor may choose to incorporate into a course. I personally believe that an undergraduate text also should devote more space to discussion of covariance structure, especially in the context of Gaussian processes, to reinforce the notions of dependence. Examples with Kalman filters, time series, and control theory are certainly within the range of applications appropriate for a text such as this one. The opening chapter is quite long, covering a wide range of basic probability concepts, such as classification of distributions according to hazard rate behavior (e.g., IFR), partial ordering of distributions, Wald’s identity, general limit theorems, and even advanced inequalities, such as Hölder’s and Minkowski’s. The concise treatment makes these results easy to refer to, but again few if any examples are given for each topic and no context in which the student might appreciate their value is provided. On the other hand, these presentations can be skipped and then returned to later as needed. Although the title claims finance as an applied area, I could find only one financial application (options pricing in the chapter on Brownian motion), unless a few applications to actuarial science are included. The bottom line is that I would not use this book as a text for either an undergraduate or a graduate course. However, I will likely put it on the reference list for my course.

Extending the Linear Model With R: Generalized Linear, Mixed Effects and Nonparametric Regression Models. Julian J. Faraway

Estimating the self-thinning line from mortality data

Afin de predire les pertes de croissance de sapins baumiers (Abies balsamea (L) Mill) soumis a des epidemies de tordeuse des bourgeons de l'epinette (Choristoneura fumiferana (Clem)), les series chronologiques de cernes annuels d'arbres dominants ont ete reliees a des releves historiques de defoliation recueillis dans la province de Quebec, Canada Ces arbres, echantillonnes sur 136 stations, ont ete abattus pour faire des analyses de tige qui ont permis de calculer des indices de croissance radiale et d'accroissements en volume pour une periode (1965-1995) couvrant la derniere epidemie de cet insecte Les variables de defoliation expliquent 36 % et 23 % de la variation interannuelle de l'indice de croissance radiale et de l'indice d'accroissement annuel en volume, respectivement Les defoliations s'etant produites jusqu'a six ans auparavant ont affecte la croissance de l'annee courante alors que les defoliations de l'annee courante n'ont eu qu'un effet limite Des defoliations severes repetees pendant plusieurs annees ont diminue de 50 % la croissance en volume des sapins baumiers dominants pendant une periode de 10 ans Ces resultats peuvent contribuer a predire la future reduction de croissance de sapins baumiers dominants soumis a differents scenarios de defoliation par la tordeuse des bourgeons de l'epinette pour de grands territoires

https://www.afs-journal.org/articles/forest/pdf/2005/03/F5029.pdf

Predicting balsam fir growth reduction caused by spruce budworm using large-scale historical records of defoliation

A model describing species composition,
density and diameter distribution of saplings was developed from operational
inventory data. It could be used as an input into growth models calibrated
exclusively with merchantable trees to correct some recruitment bias.
Important differences in distributions were found between plantations and
naturally regenerated stands. Longer-term monitoring would be required to
observe the effects of thinning treatments on saplings.
 Saplings play important ecological and structural roles in forest
stands. They also constitute the pool of candidate trees that are responsible
for recruitment of merchantable sized trees. However, sapling information is
often absent from regular inventory measurements (e.g. where no saplings are
measured) even though they could be used as inputs in predicting recruitment in
merchantable trees. The objectives were to develop models describing density and
diameter distribution of saplings from operational inventories, e.g. having only
merchantable tree inventory, and to evaluate how stand type (naturally
regenerated stands and plantations) and various thinning treatments influence
these distributions. Using data from both white spruce (Picea
glauca [Moench] Voss) plantations and naturally regenerated
balsam fir (Abies balsamea (L.) Mill.) stands
having been commercially thinned, a zero-inflated poisson regression was used to
model the stand density and a gamma regression to predict the two parameters of
the Weibull used to characterize the diameter distribution. Despite the fact that the operational inventory data is often
limited (e.g. species, dbh, height), the accuracy of the models was good and
unbiased. It could be integrated into growth models to complete missing sapling
distributions and help to correct some recruitment bias. Important differences
in species composition, density and diameter distribution were found between
plantations and naturally regenerated stands, but only a moderate response in
diameter distribution was observed with thinning treatments. These models will enable managers to estimate saplings in
intermediate aged softwood forests of eastern Quebec using harvesting
inventories or National Forest Inventory. Characterization of differences
between plantations and naturally regenerated stands will be useful for
integrating intensive plantation silviculture with ecosystem-based management.
Longer-term follow-up would be needed to better evaluate the effects of thinning
treatments.

/pdf/density-and-diameter-distributions-of-saplings-in-naturally-1xyykzxdku.pdf

Density and diameter distributions of saplings in naturally regenerated and planted coniferous stands in Québec after various approaches of commercial thinning

Cette etude porte sur l’evaluation de modeles lorsque les donnees de suivi a long terme ne sont pas disponibles ou sont tout simplement inadequates. Plus specifiquement, un modele de croissance base sur une approche par tiges individuelles a ete etalonne dans le but de prevoir la croissance des peuplements purs et equiennes de sapin baumier. Les previsions obtenues a partir de simulations stochastiques ont ensuite ete comparees a une droite d’auto-eclaircie existante. La croissance de placettes de densites initiales et de distributions diametrales variables a ete simulee sur un horizon de 70 ans a partir de 500 realisations pour chaque combinaison de densite initiale et de distribution diametrale. Les previsions a long terme se sont averees conformes a la droite d’auto-eclaircie existante, en plus de reproduire la phase de senescence durant laquelle les trajectoires de croissance s’eloignent de cette droite. Cette phase debutait lorsque le volume moyen par arbre atteignait 0,2 a 0,3 m3 par arbre, ce qui correspondait a des DHP (diametre a hauteur de poitrine, 1,3 m du sol) entre 19 et 23 cm. Bien qu’elle ne puisse etre generalisee, cette etude de cas demontre qu’un modele de croissance par tiges individuelles comprenant un indice de competition independant des distances et aucun indice de densite a l’echelle du peuplement peut reproduire une droite d’auto-eclaircie existante. Cette correspondance entre les previsions a long terme et la droite d’auto-eclaircie demontre que le modele possede un comportement biologique coherent. -- Mots-cles : Modelisation de la croissance, droite d’auto-eclaircie, phase de senescence, simulation Monte Carlo, sapin baumier, evaluation de modeles.

/pdf/evaluating-a-single-tree-based-growth-model-for-even-aged-22vlgm5m5q.pdf

Evaluating a single tree-based growth model for even-aged stands against the maximum size–density relationship: Some insights from balsam fir stands in Quebec, Canada

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Stéphane Tremblay

Author Tools

Chat about Author

Papers

Predicting balsam fir growth reduction caused by spruce budworm using large-scale historical records of defoliation

Density and diameter distributions of saplings in naturally regenerated and planted coniferous stands in Québec after various approaches of commercial thinning

Evaluating a single tree-based growth model for even-aged stands against the maximum size–density relationship: Some insights from balsam fir stands in Quebec, Canada