Variation in specific needle area (SNA; cm2 projected fresh needle area g-1 oven-dried needle weight) was investigated in relation to needle age, within-crown position and epicormic shoot production in 450-year-old Douglas-fir (Pseudotsuga menziesii Mirb. (Franco) var. menziesii) trees. Specific needle area decreased with increasing needle age. The magnitude and rate of change in SNA with needle age were greatest for lower-crown branches, and decreased toward the middle- and upper-crown branches. For all branches, there was no difference between regular and epicormic shoots in the relationship between SNA and needle age. Specific needle area decreased with increasing distance from branch base, and this relationship was significant for the majority of needle age classes of the upper- and middle-crown branches. In the lowercrown branches, SNA did not vary with distance from branch base for the majority of needle age classes. For all branches, there was no difference between regular and epicormic shoots in the relationship between SNA and distance from branch base for the majority of needle age classes. These results indicate that renewal of foliage by epicormic shoot production maintains needle quality. Branch SNA increased linearly with decreasing height in the crown at a mean rate of 0.951 +/- 0.110 cm2 g-1 per vertical meter. Total needle area of branches was estimated from total needle dry weight taking into account within-branch variation in SNA. Analyses of allometric relationships between branch size and foliage amount (needle area and needle dry weight) showed that branch length was a better predictor of foliage amount than branch diameter for old Douglas-fir trees. Total needle dry weight and needle area of the sample trees, estimated from branch length and branch height and taking into account vertical within-crown variation in branch SNA, ranged from 42.4 to 154.2 kg and from 246.2 to 816.0 m2 per tree, respectively.

Crown structure of old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is characterized by low live-branch density, numerous dead branches and epicormic branches, high branch-size variability, and large gaps in the crown. These features define structural complexity of the crown and create variable crown microenvironments. For the 60 m tall, 400-year-old Douglas-fir trees measured in this study, number of live branches decreased and dead branches increased from the upper to lower crown. Dead branches were found below the lowest live branch indicating that crown recession had occurred. Live-branch biomass culminated at 45 m and decreased markedly below 35 m. Numerous vertical gaps between branches occurred below 40 m. Epicormic branches accounted for 14.6-47.5% of the total number of live branches per tree and contributed to increased crown depth. Epicormic branches filled inner regions of the crown, and contributed to increased branch-size variability. A model of crown structure developed for young trees could be fit to the upper crown of the study trees but could not be applied to the middle to lower crown because of increased branch-size variability. Relative levels of photosynthetically active radiation in the crown decreased with decreasing height, but a local peak occurred around 35-40 m, coinciding with the height of marked decrease in live-branch biomass.Résumé : La structure du houppier du douglas de Menzies (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) présent dans les forêts surannées est caractérisée par une faible densité des branches vivantes, de nombreuses branches mortes et branches adventives, une forte variabilité dans la taille des branches et de fortes trouées dans le houppier. Ces caractéristiques définissent la complexité structurale du houppier et y créent un micro-environnement variable. Pour les douglas de 60 m de hauteur et de 400 ans d'âge mesurés dans cette étude, le nombre de branches vivantes diminuait et le nombre de branches mortes augmentait de la partie supérieure à la partie inférieure du houppier. Des branches mortes ont été trouvées sous la dernière branche vivante, indiquant un élagage actif du houppier. La biomasse des branches vivantes culminait à 45 m et diminuait de façon marquée au-dessous de 35 m. De nombreuses trouées verticales entre les branches apparaissaient au-dessous de 40 m. Les branches adventives représentaient de 14,6 à 47,5% du nombre total de branches vivantes par arbre et contribuaient à augmenter la profondeur du houppier. Les branches adventives remplissaient la partie intérieure du houppier et contribuaient à augmenter la variabilité de la taille des branches. Un modèle de structure du houppier développé pour des jeunes arbres pouvait s'ajuster à la partie supérieure des arbres de l'étude mais ne pouvait être appliqué aux parties médiane et inférieure du fait de l'augmentation de la variabilité dans la taille des branches. Le rayonnement photosynthétiquement actif relatif dans le houppier diminuait avec la hauteur mais un ...

The atomic-level tunability of molecular structures is a compelling reason to develop homogeneous catalysts for challenging reactions such as the electrochemical reduction of carbon dioxide to valuable C1–C n products. Of particular interest is methane, the largest component of natural gas. Herein, we report a series of three isomeric rhenium tricarbonyl complexes coordinated by the asymmetric diimine ligands 2-(isoquinolin-1-yl)-4,5-dihydrooxazole (quin-1-oxa), 2-(quinolin-2-yl)-4,5-dihydrooxazole (quin-2-oxa), and 2-(isoquinolin-3-yl)-4,5-dihydrooxazole (quin-3-oxa) that catalyze the reduction of CO2 to carbon monoxide and methane, albeit the latter with a low efficiency. To our knowledge, these complexes are the first examples of rhenium­(I) catalysts capable of converting carbon dioxide into methane. Re­(quin-1-oxa)­(CO)3Cl (1), Re­(quin-2-oxa)­(CO)3Cl (2), and Re­(quin-3-oxa)­(CO)3Cl (3) were characterized and studied using a variety of electrochemical and spectroscopic techniques. In bulk electrolysis experiments, the three complexes reduce CO2 to CO and CH4. When the controlled-potential electrolysis experiments are performed at −2.5 V (vs Fc+/0) and in the presence of the Brønsted acid 2,2,2-trifluoroethanol, methane is produced with turnover numbers that range from 1.3 to 1.8. Isotope labeling experiments using 13CO2 atmosphere produce 13CH4 (m/z = 17) confirming that methane originates from CO2 reduction. Theoretical calculations are performed to investigate the mechanistic aspects of the 8e–/8H+ reduction of CO2 to CH4. A ligand-assisted pathway is proposed to be an efficient pathway in the formation of CH4. Delocalization of the electron density on the (iso)­quinoline moiety upon reduction stabilizes the key carbonyl intermediate leading to additional reactivity of this ligand. These results should aid the development of more robust catalytic systems that produce CH4 from CO2.

Crown structure of old-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) is characterized by low live-branch density, numerous dead branches and epicormic branches, high branch-size variability, and large gaps in the crown. These features define structural complexity of the crown and create variable crown microenvironments. For the 60 m tall, 400-year-old Douglas-fir trees measured in this study, number of live branches decreased and dead branches increased from the upper to lower crown. Dead branches were found below the lowest live branch indicating that crown recession had occurred. Live-branch biomass culminated at 45 m and decreased markedly below 35 m. Numerous vertical gaps between branches occurred below 40 m. Epicormic branches accounted for 14.6-47.5% of the total number of live branches per tree and contributed to increased crown depth. Epicormic branches filled inner regions of the crown, and contributed to increased branch-size variability. A model of crown structure developed for young trees could be fit to the upper crown of the study trees but could not be applied to the middle to lower crown because of increased branch-size variability. Relative levels of photosynthetically active radiation in the crown decreased with decreasing height, but a local peak occurred around 35-40 m, coinciding with the height of marked decrease in live-branch biomass.Résumé : La structure du houppier du douglas de Menzies (Pseudotsuga menziesii (Mirb.) Franco var. menziesii) présent dans les forêts surannées est caractérisée par une faible densité des branches vivantes, de nombreuses branches mortes et branches adventives, une forte variabilité dans la taille des branches et de fortes trouées dans le houppier. Ces caractéristiques définissent la complexité structurale du houppier et y créent un micro-environnement variable. Pour les douglas de 60 m de hauteur et de 400 ans d'âge mesurés dans cette étude, le nombre de branches vivantes diminuait et le nombre de branches mortes augmentait de la partie supérieure à la partie inférieure du houppier. Des branches mortes ont été trouvées sous la dernière branche vivante, indiquant un élagage actif du houppier. La biomasse des branches vivantes culminait à 45 m et diminuait de façon marquée au-dessous de 35 m. De nombreuses trouées verticales entre les branches apparaissaient au-dessous de 40 m. Les branches adventives représentaient de 14,6 à 47,5% du nombre total de branches vivantes par arbre et contribuaient à augmenter la profondeur du houppier. Les branches adventives remplissaient la partie intérieure du houppier et contribuaient à augmenter la variabilité de la taille des branches. Un modèle de structure du houppier développé pour des jeunes arbres pouvait s'ajuster à la partie supérieure des arbres de l'étude mais ne pouvait être appliqué aux parties médiane et inférieure du fait de l'augmentation de la variabilité dans la taille des branches. Le rayonnement photosynthétiquement actif relatif dans le houppier diminuait avec la hauteur mais un ...

Three studies examined whether perceived increase in women’s “voice” (i.e., being heard and taken seriously about sexual assault) contributes to perceptions of bias against men. In Study 1, both men and women who perceived women to have a greater voice related to sexual assault, perceived greater victimization of men. This relationship was stronger for relatively conservative participants. In Study 2, relatively conservative (but not relatively liberal) participants who read about #MeToo perceived greater men’s victimization than those in the control condition. Study 3 examined responses to perceiving that men are victimized by #MeToo. For relatively conservative (but not liberal) men, perceptions of men’s victimhood led to less willingness to work alone with a woman and less willingness to combat sexual assault (relative to a control condition). Thus, while the #MeToo movement brings awareness of issues of sexual assault, it also generates a backlash among the more conservative, and may accentuate gender disparities.