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  • 1
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    Photoperiod and temperature as dominant environmental drivers triggering secondary growth resumption in Northern Hemisphere conifers (2020)
    National Academy of Sciences
    Details
    Publication Date: 2020-08-05
    Description: Wood formation consumes around 15% of the anthropogenic CO2emissions per year and plays a critical role in long-term sequestration of carbon on Earth. However, the exogenous factors driving wood formation onset and the underlying cellular mechanisms are still poorly understood and quantified, and this hampers an effective assessment of terrestrial forest productivity and carbon budget under global warming. Here, we used an extensive collection of unique datasets of weekly xylem tissue formation (wood formation) from 21 coniferous species across the Northern Hemisphere (latitudes 23 to 67°N) to present a quantitative demonstration that the onset of wood formation in Northern Hemisphere conifers is primarily driven by photoperiod and mean annual temperature (MAT), and only secondarily by spring forcing, winter chilling, and moisture availability. Photoperiod interacts with MAT and plays the dominant role in regulating the onset of secondary meristem growth, contrary to its as-yet-unquantified role in affecting the springtime phenology of primary meristems. The unique relationships between exogenous factors and wood formation could help to predict how forest ecosystems respond and adapt to climate warming and could provide a better understanding of the feedback occurring between vegetation and climate that is mediated by phenology. Our study quantifies the role of major environmental drivers for incorporation into state-of-the-art Earth system models (ESMs), thereby providing an improved assessment of long-term and high-resolution observations of biogeochemical cycles across terrestrial biomes.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 2
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    Wood density in Norway spruce: changes with thinning intensity and tree age (2005)
    Canadian Science Publishing
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    Publication Date: 2005-07-01
    Description: The effect of thinning intensity on growth and wood density in Norway spruce (Picea abies (L.) Karst.) was investigated in two long-term thinning experiments in southeastern Finland. The stands were approaching maturity, and their development had already been studied for 30 years. The intensities of thinning were low, normal, and high (i.e., the stand basal area after the thinning was, on average, 40, 27, and 24 m2·ha1, respectively, in Heinola, and 30, 28, and 17 m2·ha1 in Punkaharju, respectively). Compared with the low thinning intensity, the normal and high thinning intensities increased the basal-area increment of individual trees by 52% and 68%, respectively. Normal and high thinning intensities resulted in a relatively small reduction (1%4%) of mean ring density compared with low thinning intensity. The random variation in wood density between and within trees was large. About 27% of the total variation in wood density was related to variation between rings. Our results indicate that the prevailing thinning intensities in Norway spruce stands in Fennoscandia cause no marked changes in wood density. At least, the possible reduction in wood density is low compared with the increase in individual tree growth.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 3
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    Seasonal dynamics of the radial increment of Scots pine and Norway spruce in the southern and middle boreal zones in Finland (2009)
    Canadian Science Publishing
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    Publication Date: 2009-03-01
    Description: In the Finnish National Forest Inventory thousands of trees are cored every year. Based on the increment cores we assessed the progress of the radial increment in Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies (L.) Karst.) during the growing season. Data for 18 and 15 years were available from the southern and middle boreal zones, respectively. No major differences were found in the progress of the radial increment between either tree species or vegetation zones. In both zones, the radial increment began at approximately the same time, in late May or early June. On average, half of the annual radial increment was completed in early July, and ceased in late July or early August. However, there was large variation among years in the progress of the radial increment. On average, the radial-increment period (10%–90% of the total increment) was 41–59 days depending on tree species and region. The increment period was slightly shorter in the middle boreal zone, as increment ended 5–11 days later in the southern boreal zone. The variation of annual radial-increment indices was related to the dates of increment onset and cessation. However, increment-period length was more closely related to the differences in increment indices.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 4
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    Effect of stand density on radial growth of branches of Scots pine in southern and central Finland (1999)
    Canadian Science Publishing
    Details
    Publication Date: 1999-09-01
    Description: Branch growth dynamics in Scots pine (Pinus sylvestris L.) were studied in 19 thinning experiments in southern and central Finland. Data were collected from 229 trees growing on sites of different fertility with different stand density, age, and canopy position. Radial increments were measured from discs from the base of the thickest branch on every fifth living whorl. Branch growth declined gradually from the upper part of the crown towards the crown base. Near the crown base, the effect of stand density was most apparent and branches remained alive without forming annual rings. After the thinnings, branch growth did not increase, but wider spacing delayed the reduction in branch growth and increased branch longevity. Correlation of branch increment between trees was greater in the upper whorls than in the lower crown. Correlation of the radial increment between whorls of different ages was greater between whorls near each other than between whorls from the upper and lower crown. Variation of the annual increments was similar in the stem and branches. A model was developed for predicting branch increment at different heights in the crown. The best independent variables for indicating branch increment were stem radial increment, height/diameter ratio, and branch age.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 5
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    Growth, suppression, death, and self-pruning of branches of Scots pine in southern and central Finland (1999)
    Canadian Science Publishing
    Details
    Publication Date: 1999-05-01
    Description: Branch development of Scots pine (Pinus sylvestris L.) was studied in 19 thinning experiments in southern and central Finland. Data were collected from 229 trees on sites of different fertility with different stand density, age, and canopy position. Stem sections that included the thickest branch or knot of the whorl were sawn out from the whorls below the lowest living and dead whorl. The stem sections were dissected and the years of birth, suppression, death, and occlusion of the branches were determined. Diameter growth of the branches continued for a longer time in older trees. Branch growth was also prolonged by rapid radial growth of the stem. On average, branches died 7 years after their growth cessation. The number of years that branches stayed alive after growth cessation was independent of the tree or stand characteristics. After the death of a branch, more than 40 years elapsed before the branch was occluded. Large branch diameter and rapid radial growth of the stem increased the width of the loose knot zone in the stem. The results showed that there are limited possibilities of using delayed thinnings to reduce the knottiness of timber, and artificial pruning is needed to produce timber of high quality.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 6
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    Including variation in branch and tree properties improves timber grade estimates in Scots pine stands (2018)
    Canadian Science Publishing
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    Publication Date: 2018-05-01
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 7
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    Increment and decay in Norway spruce and Scots pine after artificial logging damage (2007)
    Canadian Science Publishing
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    Publication Date: 2007-11-01
    Description: The effects of depth, size, location, and season of artificial logging damage on increment and decay of Norway spruce ( Picea abies (L.) Karst.) and Scots pine ( Pinus sylvestris L.) trees were studied in long-term experiments in central Finland. Damage types applied were root damage, root collar damage, increment borer hole, and stem damage. In root collar and stem damages, two sizes (100 or 400 cm2) and depths (shallow or deep) were applied. Five to 20 years after damaging, the damages did not result in a decrease in radial, height, or volume increment. In Norway spruce, the frequency of decay in the root collar and stem damages was high. From large and deep damages, decay spread faster than from smaller and shallow ones. In Scots pine, a lower proportion of trees were decayed compared with Norway spruce. Increment coring resulted in decay in most of the trees, but the decay spread slowly. The effect of compass direction or the month of damaging was negligible. The most common decay fungus in Norway spruce was Stereum sanguinolentum (Alb. & Schwein. Fr.:) Fr. In Scots pine, only nondecay fungi were isolated. In general, logging damages decreased sawlog production through the rejection of butt logs containing decay or discoloration.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 8
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    Predicting branch angle and branch diameter of Scots pine from usual tree measurements and stand structural information (1998)
    Canadian Science Publishing
    Details
    Publication Date: 1998-11-01
    Description: A total of 19 thinning experiments were performed in southern and central Finland to study branchiness of Scots pine (Pinus sylvestris L.). Data were collected from 229 trees of different ages and canopy positions growing on sites of different fertility and thinned to different stand densities. They were used to construct models for predicting vertical trends of branch angle and branch diameter along the stem. By using the variance component model, it was possible to separate the stand-, plot-, and tree-level variations of the dependent variables. However, as the random stand and plot effects were small, they were ignored. The random tree effect of the branch angle model was slightly higher compared with the random tree effect of the branch diameter model. Branch angle increased rapidly in the upper part of the crown, but the increase levelled off in the lower part of the stem. Branch diameter increased from the stem apex to the lower part of the crown and then decreased again towards the base of the tree. Stand density measures were significant variables in the models of branch angle and branch diameter. However, they could be excluded without loss of accuracy if variables describing dimensions of the tree were used as independent variables. Relative crown length and stem diameter were adequate tree-level variables for describing branch characteristics. Validation of the models constructed without variables describing stand density revealed no biased behaviour with respect to stand density. It was concluded that branch characteristics can be predicted from the measurement of some tree-level variables without detailed knowledge of the stand history.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 9
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    Wood-density variation of Norway spruce in relation to nutrient optimization and fibre dimensions (2002)
    Canadian Science Publishing
    Details
    Publication Date: 2002-02-01
    Description: The effect of fertilization on wood density, fibre length, fibre diameter, lumen diameter, proportion of cell wall area, and cell wall thickness of Norway spruce (Picea abies (L.) Karst.) were studied in a nutrient optimization experiment in northern Sweden. On the fertilized plots, all essential macronutrients and micronutrients were supplied in irrigation water every second day during the growing season. After 12 years' treatment, data were collected from 24 trees (40 years old) on the fertilized and control plots. Fertilization increased radial growth more than threefold, especially earlywood width, and decreased wood density by over 20% at 1.3 and 4 m height. The decrease in wood density was closely related to the proportion of latewood. The absolute wood density also decreased across the whole annual ring but proportionately more in latewood than in earlywood. A close relationship was found between the wood density and fibre properties, especially with the proportion of cell wall in a cross section of each annual ring, as well as with fibre and lumen width. The absolute cell wall thickness was clearly less related to wood density. However, rather large variations were found between individual trees in the relationship between wood density and fibre properties.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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  • 10
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    Wood density of Norway spruce in uneven-aged stands (2014)
    Canadian Science Publishing
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    Publication Date: 2014-02-01
    Description: This study focused on wood density and annual ring width in Norway spruce (Picea abies (L.) Karst.) grown in uneven-aged stands (UAS). In total, 96 trees were harvested from five UAS that had been managed by single-tree selection for decades. A data set of 27 trees from even-aged stands (EAS) was used for comparison. In the UAS trees, high density and narrow annual rings were found in the juvenile wood near the pith. Thereafter, wood density rapidly decreased until the 20th annual ring, followed by an increase toward the bark. In the outermost rings, wood density again slightly decreased. The trends in wood density in the UAS trees correspond with those reported for naturally regenerated, even-aged Norway spruce stands, with the exception of the decrease in the outermost rings. A mixed linear model with ring width, cambial age, and canopy position as fixed parameters accounted for 53% of the variation in wood density of the UAS trees. In contrast to UAS trees, EAS trees showed increased wood density in the outer rings as a result of decreasing growth rate. The abrupt change in wood density of UAS trees may affect the properties of timber sawn close to the pith.
    Print ISSN: 0045-5067
    Electronic ISSN: 1208-6037
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Canadian Science Publishing
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