Individual tree and stand-level carbon and nutrient contents across one rotation of loblolly pine plantations on a reclaimed surface mine

While reclaimed loblolly pine (Pinus taeda L.) plantations in east Texas, USA have demonstrated similar aboveground productivity levels relative to unmined forests, there is interest in assessing carbon (C) and nutrients in aboveground components of reclaimed trees. Numerous studies have previously documented aboveground biomass, C, and nutrient contents in loblolly pine plantations; however, similar data have not been collected on mined lands. We investigated C, N, P, K, Ca, and Mg aboveground contents for first-rotation loblolly pine growing on reclaimed mined lands in the Gulf Coastal Plain over a 32-year chronosequence and correlated elemental rates to stand age, stem growth, and similar data for unmined lands. At the individual tree level, we evaluated elemental contents in aboveground biomass components using tree size, age, and site index as predictor variables. At the stand-level, we then scaled individual tree C and nutrients and fit a model to determine the sensitivity of aboveground elemental contents to stand age and site index. Our data suggest that aboveground C and nutrients in loblolly pine on mined lands exceed or follow similar trends to data for unmined pine plantations derived from the literature. Diameter and height were the best predictors of individual tree stem C and nutrient contents (R ≥ 0.9473 and 0.9280, respectively) followed by stand age (R ≥ 0.8660). Foliage produced weaker relationships across all predictor variables compared to stem, though still significant (P ≤ 0.05). The model for estimating stand-level C and nutrients using stand age provided a good fit, indicating that contents aggrade over time predictably. Results of this study show successful modelling of reclaimed loblolly pine aboveground C and nutrients, and suggest elemental cycling is comparable to unmined lands, thus providing applicability of our model to related systems

Effects of Early Pruning on Ring Specific Gravity in Young Loblolly Pine Trees

Juvenile wood is not well suited for use in many forest products. Understanding factors that affect the formation of juvenile and mature wood is important when managing commercially important conifer species. The purpose of this investigation was to determine the contribution of ring age, relative height in the stem, and crown position (within or not within the green crown) on ring specific gravity of loblolly pine trees pruned at young ages. A designed experiment consisting of five treatments, control; prune at age 3 yr, age 6 yr, or age 9 yr; and at ages 3,6, and 9 yr, was established at two locations in the Piedmont region of Virginia. Wood samples were acquired at three heights along the stem 15 yr after planting. Results showed that differences in ring specific gravity of the treated plots (Half of green crown removed at each scheduled pruning) were significantly higher than that of the control plots. All variables of ring age, relative height and ring position of within or not within the green crown, were statistically significant. The results suggest that cambial age, maturation, and proximity to green crown are important for controlling whole-ring specific gravity in loblolly pine trees. 

Prise en charge de la pneumonie au stade avancé d’une démence [Management of pneumonia in advanced stage dementia]

Alzheimer's dementia is a leading cause of morbidity and mortality with devastating consequences for the affected individuals and their family. Pneumonia is a common complication in patients with advanced dementia that is frequently the direct cause of death. Despite the relatively well-established progressive and non-reversible trajectory of Alzheimer's disease, these patients still frequently receive curative treatments during the last months of their lives and access to palliative care is often delayed. The approach and therapeutic options to manage pneumonia at the advanced stage of Alzheimer's disease are discussed in this article

Modeling the impact of thinning on height development of dominant and codominant loblolly pine trees

Data collected from loblolly pine thinning study plots established in plantations on cutover, site-prepared lands were used to evaluate thinning impact on height growth of dominant and codominant loblolly pine trees. Height growth was reduced initially by thinning but was increased after 3 years following thinning. The average total height of dominant and codominant trees in thinned stands exceeded its counterpart in unthinned stands 12 years after thinning. Initial growth response to thinning was less at older stand ages than at younger ages. A model was constructed to characterize the development of height in thinned and unthinned stands. This model reflects the initial suppression of dominant and codominant height growth followed by an acceleration as a result of thinning.Modélisation de l'impact de l'éclaircie sur le développement en hauteur des arbres dominants et codominants chez Pinus taeda L. Des données récoltées dans des dispositifs expérimentaux d'étude des éclaircies, installés dans des plantations de Pinus taeda, ont été utilisées pour évaluer l'impact de l'éclaircie sur la croissance en hauteur des arbres dominants et co-dominants. La croissance en hauteur a été initialement réduite par éclaircie, mais s'est accrue dans les 3 ans suivant l'éclaircie. La moyenne de la hauteur totale des arbres dominants et codominants dans les peuplements éclaircis est supérieure à celle des arbres dominants et codominants des peuplements non éclaircis, 12 ans après l'éclaircie. La réponse initiale en termes de croissance à l'éclaircie était plus faible dans les vieux peuplements que dans les peuplements jeunes. Un modèle a été construit pour caractériser l'évolution de la croissance en hauteur dans les peuplements éclaircis et les peuplements non éclaircis. Ce modèle reflète l'effet initial dépressif de l'éclaircie sur la croissance des arbres dominants et codominants suivi d'une accélération comme résultat de l'effet d'éclaircie