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To determine sequestration rates of carbon dioxide (C[O.sub.2]) we calculated the carbon (C) storage rate in humus layers of Swedish forests with Podsolic soils, which account for 14.2 x [10.sup.6] ha of the 22.7 x [10.sup.6] ha of forested land in Sweden. Our data set covered 41 years of humus inventories and mean humus layer thickness in 82513 plots. We analysed three forest types: (i) all combinations of tree species, (ii) forests dominated (>70%) by Norway spruce (Picea abies (L.) Karst.), and (iii) forests dominated (>70%) by Scots pine (Pinus sylvestres L.). To relate changes in humus layer thickness to land area we used the intersections in 25 km x 25 km grids and used kriging interpolation, permitting calculations for each forest type. For each intersection mean humus thickness for each year was calculated and regressed against time to obtain the rate of change. This rate, humus bulk density, and humus C concentration were used to calculate sequestration rates. The mean sequestration rate was 251 kg C x [ha.sup.-1] x [year.sup.-1], which is higher than theoretical values. The sequestration rate was positively related to temperature sum, albeit including effects of forest management. The pine-dominated forest type had a mean rate of 283 kg C x [ha.sup.-1] x [year.sup.-1], and the spruce-dominated had a mean rate of 239 kg C x [ha.sup.-1] x [year.sup.-1]. Under similar site conditions, pine sequestered more C than spruce (difference of 71 kg C x [ha.sup.-1] x [year.sup.-1]; p < 0.0001), showing the importance of this type of ecosystem for C sequestration. Pour determiner le taux de sequestration du dioxyde de carbone (C[O.sub.2]), nous avons calcule le taux de stockage du carbone (C) dans la couche d'humus des forets suedoises etablies sur un sol podzolique qui representent 14,2 x [10.sup.6] ha des 22,7 x [10.sup.6] ha de foret. Nos donnees couvraient 41 annees d'inventaire de l'humus incluant la profondeur moyenne de la couche d'humus dans 82 513 placettes. L' analyse a porte sur trois types de forets : (i) les forets composees de toutes les combinaisons d'especes d'arbres; (ii) les forets dominees (>70 %) par l'epicea commun (Picea abies (L.) Karst.); (iii) les forets dominees (>70 %) par le pin sylvestre (Pinus sylvestres L.). Pour relier les variations de profondeur de l'humus a la superficie du terrain, nous avons utilise les intersections dans des grilles de 25 km x 25 km et le krigeage, ce qui permettait de faire le calcul pour chaque type de forets. A chaque intersection, la profondeur moyenne de l'humus a ete calculee pour chacune des annees et une courbe de regression a ete etablie en fonction du temps, ce quia permis d'obtenir le taux de variation. Ce taux, la densite apparente de l'humus et la concentration de C dans l'humus ont ete utilises pour calculer le taux de sequestration. Le taux moyen atteignait de 251 kg C x [ha.sup.-1] x [an.sup.-1], ce qui est plus eleve que la valeur theorique, et l'augmentation etait positivement reliee a la somme des temperatures, bien que les effets de l'amenagement forestier soient inclus. Le taux moyen etait respectivement de 283 et 239 kg C x [ha.sup.-1] x [an.sup.-1] dans le groupe de forets domine par le pin et dans le groupe domine par l'epicea. Dans des conditions similaires de station, le pin sequestrait plus de C que l'epicea (difference de 71 kg C x [ha.sup.-1] x [an.sup.-1]; p < 0,0001), ce qui montre l'importance du type d'ecosysteme pour la sequestration de C. [Traduit par la Redaction], Introduction Although soil organic matter (SOM) holds the largest carbon (C) pool on land (1.5 x [10.sup.15] kg, three times that of vegetation), little is known about the current net [...]

This study aims to complement previous studies on down-regulation of sucrose synthase and cinnamate 4-hydroxylase in hybrid aspen (Bjurhager et al. 2010; Gerber et al. 2014) with a quantitative anatomical comparison (Sandquist et al. 2015). The main focus was placed on evaluating quantitative modifications to fiber morphology and lignin composition. This was achieved by combining results from light-, electron-, and UV-microscopy together with histochemical staining. Overall there was good agreement between the morphological results in this study compared to the previously published chemical and physical reports, particularly on cinnamate 4-hydroxylase down-regulated aspen. The previously reported statistical correlations between fiber lumen area and plant diameter, and fiber length and tree height (Sandquist et al. 2015) have been further refined. Knock-down of genes coding for biologically important proteins such as sucrose synthase and cinnamate 4-hydroxylase had broad spanning morphological impacts. Downregulated sucrose synthase genotype showed significantly reduced fiber development, possibly with altered S/G ratio. Down-regulated cinnamate 4-hydroxylase genotype showed an overall reduction of lignin in fibers as indicated from both chemical staining and UV-microscopy measurements. Down-regulated pectate lyase genotype showed no overall significant effects on fiber morphology, ultrastructural, nor lignin staining. [ABSTRACT FROM AUTHOR]

A new method is presented for quantitative evaluation of hybrid aspen genotype xylem morphology and immunolabeling micro-distribution. This method can be used as an aid in assessing differences in genotypes from classic tree breeding studies, as well as genetically engineered plants. The method is based on image analysis, multivariate statistical evaluation of light, and immunofluorescence microscopy images of wood xylem cross sections. The selected immunolabeling antibodies targeted five different epitopes present in aspen xylem cell walls. Twelve down-regulated hybrid aspen genotypes were included in the method development. The 12 knock-down genotypes were selected based on pre-screening by pyrolysis-IR of global chemical content. The multivariate statistical evaluations successfully identified comparative trends for modifications in the down-regulated genotypes compared to the unmodified control, even when no definitive conclusions could be drawn from individual studied variables alone. Of the 12 genotypes analyzed, three genotypes showed significant trends for modifications in both morphology and immunolabeling. Six genotypes showed significant trends for modifications in either morphology or immunocoverage. The remaining three genotypes did not show any significant trends for modification. [ABSTRACT FROM AUTHOR]

The ANOVA estimators of the variance components are studied for the one-way random model with normally distributed effects. The study is focused on the effect of sample-size imbalance on the variance of the estimator for the between-group variance component. Lower and upper bounds for the variance of the estimator are found in terms of the sum of squares of the sample sizes. These bounds encase all possible experimental designs. The effect of imbalance is illustrated by examples. Comparisons are made with the estimators based on restricted maximum likelihood. [ABSTRACT FROM AUTHOR]

Extension growth of secondary needles is under photoperiodic control in Pinus sylvestris. To test for the effects of far-red light on maintaining this extension growth, seedlings of six populations originating from latitudes between 57° and 67°N were raised for 11 weeks in continuous incandescent (metal halogen) light at 300 µmol m-2 s-1 and 20°C and then transferred at the same temperature to a daily regime of 8 h incandescent light (230 µmol m-2 s-1) followed by a 16 h day extension with cool white fluorescent light (40 µmol m-2 s-1, R/FR ratio 7.5) or with incandescent lamps (20 µmol m-2 s-1, R/FR ratio 2.0). For the seedlings from the three populations north of 64°, needle extension growth over 42 days in the FR-poor day extension treatment was lower by up to 40% than in the FR-rich day extension treatment, whereas for the seedlings from the three southern populations the needle extension growth was similar in both day extension treatments. The requirement for FR in day extensions is characteristic of ‘light-dominant’ photoperiodic control mechanisms. It appears that P. sylvestris changes from dark-dominant night timekeeping to light-dominant day timekeeping with increasing latitude, as with the photoperiodic control of budset in Picea abies. [ABSTRACT FROM AUTHOR]

Romanian populations of Norway spruce are induced to set terminal budsby four inductive cycles of 8 h light/16 h darkness. To distinguish betweencircadian and hourglass timekeeping for the photoperiodic control of budset,seedlings were raised in continuous light at 300 μmol m[sup -2] s[sup -1] at 20°C for 10 weeks. They were then exposed to anextended night regime consisting of three cycles of 8 h light/40 h dark with4-h or 1-h nightbreaks (120 μmol m[sup -2] s[sup -1] )applied to groups of plants at intervals during the extended night. Followinga final cycle of 8 h light/16 h dark to maximize budset, the plants were transferredto continuous light. Budset was delayed when the night-break was applied closeto the critical nightlength (CNL) of 6–7 h or about 22–23 h laterin the extended night, consistent with circadian rather than hourglass timekeeping.Confidence intervals were calculated for the times to maximum effect of thenight-breaks. [ABSTRACT FROM AUTHOR]