La plantation sur monticule, un moyen efficace pour augmenter la productivité de la forêt boréale - Bilan d’une plantation d’épinettes noires de 30 ans située près du lac Chibougamau

Cette étude compare après 30 ans la croissance et le rendement d’une plantation d’épinettes noires reboisées sur différents microsites formés par le passage soit d’un scarificateur Bräcke ou d’un scarificateur à disques TTS. Les deux sites sont localisés sur la même unité physiographique dans la pessière à mousses de l’Ouest tout près de Chibougamau. Le dispositif n’a pas été construit à l’origine pour permettre les comparaisons statistiques entre les deux traitements de préparation de terrain étant donné l’absence de vraies répétitions; les comparaisons statistiques entre les microsites à l’intérieur de chaque site sont cependant valides. Les gains de croissance des plants du Bräcke par rapport à ceux du TTS sont donc donnés à titre indicatif. La hauteur, le diamètre et le volume de la tige des arbres reboisés sur le monticule formé par le Bräcke étaient significativement plus grands que ceux reboisés à l’épaulement ou dans le poquet. Nous n’avons pas observé de différences significatives entre les plants reboisés dans le fond ou l’épaulement formé par le scarificateur à disques. Après 30 ans en plantation, le gain en volume des plants sur le monticule était de 107% plus élevé comparativement aux plants reboisés après passage du scarificateur à disques TTS. Cette différence s’explique par une croissance radiale annuelle accélérée des plants sur le monticule à partir de la 4ième année en plantation sur une période s’étendant sur 19 ans. Le volume marchand prédit par les équations des modèles de prédiction actuels serait supérieur de 53 m3/ha à 60 ans pour une plantation d’épinette noire réalisée sur des monticules comparativement à une préparation traditionnelle par un scarificateur à disques. This study compare 30 years old black spruce stands planted on different microsites made by a Bräcke mounder or a disk trencher. The two sites are located on the same physiographic unit in the boreal forest near Chibougamau, northeastern Quebec. The experimental design was not planned for comparison between treatments since treatments were not replicated but comparisons betwen microsites inside each treatment are still valid. Increased yield of moundind treatrment compared to the disk trenching treatment are given for information only. Spruce height, diameter and stem volume were significantly larger on Bräcke mound than for seedlings planted in the Bräcke patch or hinge position. Stem growth was not different for the seedlings planted in the furrow or the hinge position in the disk trenching treatment. After 30 years, stem volume of seedlings planted on the Bräcke mound was 107% higher than those in the disk trenching treatment. Annual radial growth of seedlings located on mound has increased faster than those on the disk trenching treatment after a delay of four year and this vigorous growth rate was maintained for at least 19 years. Stand commercial volume was estimated to be 53 m3/ha higher after 60 years for the mounding treatment compared to the more conventional disk trenching treatment

Effets des microsites créés par le Bräcke-monticule sur la croissance de l’épinette noire et du pin gris : résultats des mesures de croissance prises 23 ans après la plantation opérationnelle du lac Caopatina

Le dispositif opérationnel mis en place en 1985 afin d’étudier le rendement du scarificateur Bräcke-monticule est situé au nord du lac Caopatina dans le canton Hazeur, sur le territoire de la compagnie Barette-Chapais. Les arbres ont été rémesurés en 2008, 23 ans après la plantation. Ce rapport a pour but de comparer les hauteurs, les DHP et les volumes de la tige des plants d’épinette noire et de pin gris reboisés sur les différents microsites créés par le Bräcke-monticule et de faire une prévision à long terme du volume marchand à partir du calcul des IQS pour les différents microsites. Les trois variables mesurant la croissance, soit la hauteur, le DHP et le volume de la tige montrent tous les trois qu’il y aurait des gains appréciables en ce qui concerne le rendement des plantations reboisant les plants sur le monticule créé par un Bräcke-monticule

Influence of Stem Taper on the Yield of Black Spruce Stands and Trees Following Commercial Thinning

In this work, we examine the effects of commercial thinning on stand volume and individual stem form in nine naturally regenerated black spruce (Picea mariana (Mill.) B.S.P.) stands. We compared these study sites with controls in the commercial boreal forest of northern Quebec, Canada. At stand level, dendrochronological data provided insight into changes in stand volume ten years after thinning. Analysis of a subsample of six individual trees from each commercially thinned stand and three individual trees from the controls illustrated the role of thinning on stem shape development. Although average volume increased for residual stems in thinned stands slightly more than in the controls (110% versus 106%), the treatment effect stand-level volume increment or stand-level total volume harvested (ten years after treatment) was not statistically significant. Moreover, at tree level, thinning did not significantly affect stem volume increment. However, radial growth increment significantly increased after treatment. Trees from commercially thinned stands showed a significantly higher growth increment along the lower first two-thirds of the stem. Response to thinning at tree level correlated strongly with the size and number of harvested competitors around a residual stem. We conclude that commercial thinning modified wood allocation rather than wood volume and did not affect taper and stem shape. These patterns of post-cutting growth are explained by wood allocation following thinning. After commercial thinning, growth increment is favored at the expense of height growth. As the treatment effect was found at the stem scale rather than at the stand scale, further research is needed in regard to commercial thinning treatments to investigate how to increase productivity at the stand scale

Primary and secondary branch growth in black spruce and balsam fir after Careful Logging around small Merchantable Stems (CLASS).

Careful logging around small merchantable stems (CLASS) is a partial cutting treatment that consists of the harvest of 70%–90% of the merchantable volume of an irregular coniferous stand. In this treatment, regeneration, saplings and small merchantable stems (DBH < 15 cm) are preserved and can continue to grow and develop into the dominant layer of the new stand. The aim of this project was to examine the effects of CLASS on the primary and secondary growth of branches, as well as on branch diameter in black spruce and balsam fir trees in the boreal forest of Quebec, Canada. Primary and secondary growth were measured on five branches per tree while branch diameter was analysed from 15 whorls distributed within the crown of the 48 black spruce and 48 balsam fir trees sampled. Branch primary and secondary growth significantly increased after CLASS in the lower part of the crown in both species, and both types of growth increased proportionally. These findings suggest that CLASS may delay crown recession as the lower branches tend to survive and grow for a longer period. However, although radial growth increased in the years post-CLASS, this did not significantly influence the final branch diameter and should not lead to lumber downgrade

On reduced relatives with genitive subjects

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2001.Includes bibliographical references (leaves 222-232).What is the place of relatives with genitive subjects in a typology of relative clauses? Are they full or reduced, headed or free relatives? Can they appear pre- and postnominally? Can they be head-internal relatives? Are they finite or non-finite? Can they be restrictives and appositives? These are the questions that this thesis will address. Full relatives have nominative subjects. Thus, relatives with genitive subjects are not full relatives. Relatives with genitive subjects share, however, many properties with reduced relatives. Among others, both prohibit relative pronouns and complementizers. Both employ participles, i.e., verbs that lack tense but exhibit nominal properties. Both prohibit nominative subjects. Therefore, it will be argued that relative clauses with genitive subjects are reduced relatives. There exists, however, one difference between relative clauses with genitive subjects and standard reduced relatives. Only the former permits non-subject relativization. It will be argued that reduced relatives are headed by a NP and that the difference in permitting genitive subjects is caused by a difference in the case licensing mechanisms within this NP. Only if N can license structural genitive case can a language have relative clauses with genitive subjects. The verb in reduced relatives lacks tense. If the finite/non-finite distinction is based on the presence of tense, then reduced relatives are non-finite clauses.(cont.) Furthermore, there are no non-finite free relatives. Thus, reduced relatives must be headed relatives. Finally, reduced relatives cannot be appositives. Appositives are full clauses. Thus, reduced relatives can only be restrictive relatives. In certain contexts, however, reduced relatives permit another reading. They can receive Free Adjunct interpretations. This is because Free Adjuncts too are smaller than CP. Thus they depend on the matrix clause for their temporal interpretation. This can result in a reading according to which the events in the matrix and the adjunct clause co-occur, i.e., in a when-reading and in an if-reading if the matrix clause contains a modal. The reading that is always available to reduced adjunct clauses is the because-reading, which as a default is the most salient way for the adjunct to establish a logical connection to the matrix clause.by Cornelia Krause.Ph.D

Unveiling the diversity of tree growth patterns in boreal old-growth forests reveals the richness of their dynamics

Research Highlights: Radial growth patterns of trees growing in old-growth boreal forests in eastern Canada can be grouped into a small number of simple patterns that are specific to different old-growth forest types or successional stages. Background and Objectives: Identifying the main radial growth trends in old-growth forests could help to develop silvicultural treatments that mimic the complex dynamics of old-growth forests. Therefore, this study aimed to identify the main radial growth patterns and determine how their frequencies change during forest succession in old-growth forests, focusing on boreal landscapes in eastern Canada. Materials and Methods: We used dendrochronological data sampled from 21 old-growth stands in the province of Quebec, Canada. Tree-ring chronologies were simplified into chronologies of equal length to retain only primary growth trends. We used k-means clustering to identify individual growth patterns and the difference in growth-pattern frequency within the studied stands. We then used non-parametric analyses of variance to compare tree or stand characteristics among the clusters. Results: We identified six different growth patterns corresponding to four old-growth forest types, from stands at the canopy breakup stage to true old-growth stands (i.e., when all the pioneer cohort had disappeared). Secondary disturbances of low or moderate severity drove these growth patterns. Overall, the growth patterns were relatively simple and could be generally separated into two main phases (e.g., a phase of limited radial increment size due to juvenile suppression and a phase of increased radial increment size following a growth release). Conclusions: The complexity of old-growth forest dynamics was observed mainly at the stand level, not at the tree level. The growth patterns observed in true old-growth forests were similar to those observed following partial or stem-selection cuts in boreal stands; thus, these silvicultural treatments may be effective in mimicking old-growth dynamics

Dynamics of depletion and replenishment of water storage in stem and roots of black spruce measured by dendrometers

In the short term, trees rely on the internal storage of water because it affects their ability to sustain photosynthesis and growth. However, water is not rapidly available for transpiration from all the compartments of the plant and the living tissues of the stem act as a buffer to preclude low water potentials during peaks of transpiration. In this paper, electronic dendrometers were used from mid-June to mid-September 2008 to compare the radius variations in stem and roots of black spruce [Picea mariana (Mill.) B.S.P.] in two sites of the boreal forest of Quebec, Canada, with different soil characteristics and water retention. The duration of the daily cycles was similar between sites and measurement heights but greater amplitudes of contraction and expansion were observed on the stem and in the site with the shallowest soil organic layer. The expansion phase had higher amplitudes and lasted longer than contraction. On average, the contraction phase occurred between 07:00 and 16:30 (legal time), while expansion lasted 14.5 h. The roots in the site with the deepest organic layer showed a wider variation in the onset of contraction, which could be as late as 13:00. The probability of observing the contraction phase depended on precipitation. With a precipitation 60% probability of observing contraction between 05:00 and 21:00, decreasing to 20% with precipitation >1.1 mm h−1. These findings demonstrated that the depth of the organic layer plays an important role in maintaining the internal water reserve of trees. The dynamics of water depletion and replenishment can modify the water potential of xylem and cell turgor during the enlargement phase, thus affecting radial growth. Changes in temperature and precipitation regime could influence the dynamics of internal water storage in trees growing on shallower and drier soils

A three-step procedure in SAS to analyze the time series from automatic dendrometers

Continuous measurements of stem radius variation in trees are obtained with automatic dendrometers that provide time series composed of seasonal tree growth and circadian rhythms of water storage and depletion. Several variables can be extracted from the raw data, such as amplitude and duration of radius increase and contraction, which are useful for understanding intra-annual tree growth, tree physiology and for performing growth-climate relationships. These measurements constitute a large dataset whose manipulation needs numerous algorithms and automatic procedures to efficiently and rapidly extract the information. This paper presents a three-step procedure using two SAS routines to extract the time series describing radius variation and associate them with environmental parameters. The first routine organizes and corrects data and generates outputs in the form of files and plots to visualize the results and improve data correction (first step). The second step consists of a reclassification of the hours of contraction or expansion that have been misclassified by the automatic process. The second routine classifies the daily patterns of stem variation into the three phases of contraction, expansion and radius increment and associates the environmental parameters (third step). An example of the procedure is given, with an explanation of the outputs generated. The advantages and shortcomings of the procedure and its importance for the intra-annual analyses of tree growth are discussed

Sexualized Behavior Among Adolescents Who Sexually Offended

Early or excessive sexualized behaviors and preoccupations with sexuality (SB) exhibited by juveniles who have sexually offended (JSO) are considered risk factors for sexual recidivism. However, research into SB among JSO is scarce. The present study retrospectively examined prevalence rates and patterns of SB among JSO prior to sexual offending and their relation to psychopathology and sexual recidivism. We systematically assessed information from psychiatric and psychological expert reports in case files of 230 JSO aged 12–18 years (M = 14.46, SD = 1.49) from a population sample of JSO with contact sexual offenses. A total of 93 (40.4%) JSO exhibited SB prior to the index sexual offense. Latent class analysis revealed three SB profiles: (1) “low/no SB” (n = 188), (2) “preoccupied SB” (preoccupation with sexuality, e.g., early pornography consumption, excessive masturbation; n = 29), and (3) “dysregulated SB” (exhibiting inappropriate sexualized behaviors toward others, e.g., sexualized speech, touching others inappropriately; n = 13). The preoccupied SB and the dysregulated SB groups showed higher prevalence of psychiatric disorders than the low/no SB. However, none of the JSO of the preoccupied SB or dysregulated SB groups reoffended sexually within 365 days after conviction for the sexual index offense (low/no SB: 12.8%). Overall, our findings do not support a general notion of the presence of SB as an indicator of high risk for persistent sexual offending among JSO. Instead, JSO with SB appear particularly burdened regarding a range of psychiatric disorders that should be treated accordingly