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  • 1
    Language: English
    In: Plant, cell and environment, 2016-02, Vol.39 (2), p.233-244
    Description: The quantification of cambial growth over short time periods has been hampered by problems to discern between growth and the swelling and shrinking of a tree stem. This paper presents a model, which separates cambial growth and reversible water‐potential induced diurnal changes from simultaneously measured whole stem and xylem radial variations, from field‐measured Scots pine trees in Finland. The modelled growth, which includes osmotic concentration changes, was compared with (direct) dendrometer measurements and microcore samples. In addition, the relationship of modelled growth and dendrometer measurements to environmental factors was analysed. The results showed that the water‐potential induced changes of tree radius were successfully separated from stem growth. Daily growth predicted by the model exhibited a high correlation with the modelled daily changes of osmotic concentration in phloem, and a temperature dependency in early summer. Late‐summer growth saw higher dependency on water availability and temperature. Evaluation of the model against dendrometer measurements showed that the latter masked a true environmental signal in stem growth due to water‐potential induced changes. The model provides better understanding of radial growth physiology and offers potential to examine growth dynamics and changes due to osmotic concentration, and how the environment affects growth. This paper introduces a model that separates water‐potential induced changes from field‐sampled dendrometer measurements, revealing a cambial growth and osmotic concentration signal. Using this signal, we investigate how environmental factors influence stem growth and tree physiology, which would otherwise be masked by water‐related changes. This is important for understanding how factors affect physiological processes of the tree and developing a robust method to quantifying osmotic‐related stem radial changes and stem growth.
    Subject(s): hydraulic conductance ; xylem ; phloem ; dendrometer ; elasticity ; Temperature ; Xylem - physiology ; Osmosis ; Photons ; Pressure ; Plant Stems - physiology ; Cambium - growth & development ; Regression Analysis ; Rain ; Environment ; Seasons ; Photosynthesis ; Water - physiology ; Plant Stems - growth & development ; Water ; Physiological aspects ; Erythromycin ; Growth ; Analysis
    ISSN: 0140-7791
    E-ISSN: 1365-3040
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Global change biology, 2016-11, Vol.22 (11), p.3804-3813
    Description: The interaction between xylem phenology and climate assesses forest growth and productivity and carbon storage across biomes under changing environmental conditions. We tested the hypothesis that patterns of wood formation are maintained unaltered despite the temperature changes across cold ecosystems. Wood microcores were collected weekly or biweekly throughout the growing season for periods varying between 1 and 13 years during 1998–2014 and cut in transverse sections for assessing the onset and ending of the phases of xylem differentiation. The data set represented 1321 trees belonging to 10 conifer species from 39 sites in the Northern Hemisphere and covering an interval of mean annual temperature exceeding 14 K. The phenological events and mean annual temperature of the sites were related linearly, with spring and autumnal events being separated by constant intervals across the range of temperature analysed. At increasing temperature, first enlarging, wall‐thickening and mature tracheids appeared earlier, and last enlarging and wall‐thickening tracheids occurred later. Overall, the period of wood formation lengthened linearly with the mean annual temperature, from 83.7 days at −2 °C to 178.1 days at 12 °C, at a rate of 6.5 days °C−1. April–May temperatures produced the best models predicting the dates of wood formation. Our findings demonstrated the uniformity of the process of wood formation and the importance of the environmental conditions occurring at the time of growth resumption. Under warming scenarios, the period of wood formation might lengthen synchronously in the cold biomes of the Northern Hemisphere.
    Subject(s): cell production ; cell differentiation ; secondary wall formation ; cambium ; conifers ; meristem ; growth ; climate change ; Trees ; Cold Temperature ; Plant Development ; Xylem ; Ecosystem ; Coniferophyta ; Seasons ; Biomes ; Environmental aspects ; Global temperature changes ; Cell differentiation ; Ecosystems ; Analysis ; Life Sciences ; Vegetal Biology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 3
    Language: English
    In: Canadian journal of forest research, 2018, Vol.48 (6), p.721-728
    Description: Storms cause major forest disturbances in Europe. The aim of this study was to model tree-level storm damage probability based on the properties of a tree and its environment and to examine whether fine-scale topographic information is connected to the damage probability. We used data documenting effects of two autumn storms on over 17 000 trees on permanent Finnish National Forest Inventory plots. The first storm was associated with wet snowfall that damaged trees, while exceptionally strong winds and gusts characterized the second storm. During the storms, soils were unfrozen and deciduous trees were without leaves. Generalized linear mixed models were used to study how topographical variables calculated from digital elevation models (DEM) with resolutions of 2 and 10 m (TOPO2 and TOPO10, respectively) were related to damage probability, in addition to variable groups for tree (TREE) and stand (STAND) characteristics. We compared models containing different variable groups with Akaike information criteria. The best model contained the variable groups TREE, STAND, and TOPO2. Increase in slope steepness calculated from the high-resolution DEM decreased tree-level damage probability significantly in the model. This suggests that the local topography affects the tree-level damage probability and that high-resolution topographical data improves the tree-level damage probability models.
    Subject(s): tempête de vent ; dommages causés par le vent ; snow damage ; digital elevation model ; wind damage ; chablis ; dommages causés par la neige ; wind storm ; modèle altimétrique numérique ; windthrow ; Environmental aspects ; Usage ; Mathematical models ; Storm damage
    ISSN: 0045-5067
    E-ISSN: 1208-6037
    Source: Academic Search Ultimate
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  • 4
    Language: English
    In: Canadian journal of forest research, 2018, Vol.48 (5), p.542-553
    Description: Deterministic modelling of roundwood quality with expected values of quality factors underestimates the variation in timber grade distribution and leads to sudden transitions of all of the trees in a size class between the quality classes. We constructed a recursive model chain that predicts the height of the lowest living and dead branches for a set of maximum branch diameters based on stem diameter, tree height, and height of the crown base. By using Monte-Carlo simulation, a timber grade distribution for a stand was integrated over the multidimensional random distribution of the recursive model chain. The results demonstrated that introducing random variation resulted in major changes in the calculated quality distributions. The timber grade distributions were wider compared with the expected value-based predictions. In particular, the proportions of the highest and lowest quality classes were under- or over-estimated in the deterministic predictions. Because of the random variation of tree properties, the timber grade distribution also became more continuous over time. The results also showed that the timber grade distributions can vary considerably between stands with similar stem diameter distributions. Understanding the effects of random quality variation will give guidance to forest managers to reach more profitable management regimes.
    Subject(s): timber quality ; branchaison ; branchiness ; Scots pine ; random variation ; simulation ; qualité du bois d’œuvre ; variation aléatoire ; pin sylvestre ; Physiological aspects ; Models ; Properties ; Pine ; Timber
    ISSN: 0045-5067
    E-ISSN: 1208-6037
    Source: Academic Search Ultimate
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  • 5
    Language: English
    In: Biogeosciences, 2017-06-23, Vol.14 (12), p.3083-3095
    Description: Latitudinal and altitudinal gradients can be utilized to forecast the impact of climate change on forests. To improve the understanding of how these gradients impact forest dynamics, we tested two hypotheses: (1) the change of the tree growth–climate relationship is similar along both latitudinal and altitudinal gradients, and (2) the time periods during which climate affects growth the most occur later towards higher latitudes and altitudes. To address this, we utilized tree-ring data from a latitudinal gradient in Finland and from two altitudinal gradients on the Tibetan Plateau. We analysed the latitudinal and altitudinal growth patterns in tree rings and investigated the growth–climate relationship of trees by correlating ring-width index chronologies with climate variables, calculating with flexible time windows, and using daily-resolution climate data. High latitude and altitude plots showed higher correlations between tree-ring chronologies and growing season temperature. However, the effects of winter temperature showed contrasting patterns for the gradients. The timing of the highest correlation with temperatures during the growing season at southern sites was approximately 1 month ahead of that at northern sites in the latitudinal gradient. In one out of two altitudinal gradients, the timing for the strongest negative correlation with temperature at low-altitude sites was ahead of treeline sites during the growing season, possibly due to differences in moisture limitation. Mean values and the standard deviation of tree-ring width increased with increasing mean July temperatures on both types of gradients. Our results showed similarities of tree growth responses to increasing seasonal temperature between latitudinal and altitudinal gradients. However, differences in climate–growth relationships were also found between gradients due to differences in other factors such as moisture conditions. Changes in the timing of the most critical climate variables demonstrated the necessity for the use of daily-resolution climate data in environmental gradient studies.
    Subject(s): Influence ; Climatic changes ; Research ; Tree-rings
    ISSN: 1726-4189
    ISSN: 1726-4170
    E-ISSN: 1726-4189
    Source: Alma/SFX Local Collection
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 6
    Language: English
    In: Scientific reports, 2018-01-22, Vol.8 (1), p.1339-12
    Description: The large volcanic eruptions of AD 536 and 540 led to climate cooling and contributed to hardships of Late Antiquity societies throughout Eurasia, and triggered a major environmental event in the historical Roman Empire. Our set of stable carbon isotope records from subfossil tree rings demonstrates a strong negative excursion in AD 536 and 541-544. Modern data from these sites show that carbon isotope variations are driven by solar radiation. A model based on sixth century isotopes reconstruct an irradiance anomaly for AD 536 and 541-544 of nearly three standard deviations below the mean value based on modern data. This anomaly can be explained by a volcanic dust veil reducing solar radiation and thus primary production threatening food security over a multitude of years. We offer a hypothesis that persistently low irradiance contributed to remarkably simultaneous outbreaks of famine and Justinianic plague in the eastern Roman Empire with adverse effects on crop production and photosynthesis of the vitamin D in human skin and thus, collectively, human health. Our results provide a hitherto unstudied proxy for exploring the mechanisms of 'volcanic summers' to demonstrate the post-eruption deficiencies in sunlight and to explain the human consequences during such calamity years.
    Subject(s): Food Supply ; Dust ; Environmental Monitoring ; History, Medieval ; Humans ; Volcanic Eruptions - history ; Carbon Isotopes - analysis ; Fossils ; Trees - chemistry ; Crop production ; Outbreaks ; Irradiance ; Plague ; Famine ; Vitamin D ; Food security ; Roman civilization ; Skin ; Solar radiation ; Photosynthesis ; Isotopes ; Primary production
    ISSN: 2045-2322
    E-ISSN: 2045-2322
    Source: Nature Open Access
    Source: Academic Search Ultimate
    Source: PubMed Central
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  • 7
    Language: English
    In: The New phytologist, 2015-04-01, Vol.206 (2), p.647-659
    Description: The control of tree growth vs environment by carbon sources or sinks remains unresolved although it is widely studied. This study investigates growth of tree components and carbon sink–source dynamics at different temporal scales. We constructed a dynamic growth model ‘carbon allocation sink source interaction’ (CASSIA) that calculates tree-level carbon balance from photosynthesis, respiration, phenology and temperature-driven potential structural growth of tree organs and dynamics of stored nonstructural carbon (NSC) and their modifying influence on growth. With the model, we tested hypotheses that sink demand explains the intra-annual growth dynamics of the meristems, and that the source supply is further needed to explain year-to-year growth variation. The predicted intra-annual dimensional growth of shoots and needles and the number of cells in xylogenesis phases corresponded with measurements, whereas NSC hardly limited the growth, supporting the first hypothesis. Delayed GPP influence on potential growth was necessary for simulating the yearly growth variation, indicating also at least an indirect source limitation. CASSIA combines seasonal growth and carbon balance dynamics with long-term source dynamics affecting growth and thus provides a first step to understanding the complex processes regulating intra- and interannual growth and sink–source dynamics.
    Subject(s): Full papers ; xylogenesis ; growth variation ; sink–source dynamics ; phenology ; carbon (C) balance ; dynamic modelling ; thermal time ; ontogenetic development ; Carbon - metabolism ; Pinus sylvestris - growth & development ; Phenotype ; Temperature ; Cell Respiration ; Plant Leaves - metabolism ; Models, Biological ; Plant Leaves - growth & development ; Pinus sylvestris - metabolism ; Seasons ; Carbon Sequestration ; Photosynthesis ; Models ; Growth ; Statistics ; Analysis ; Phytochemistry
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 8
    Language: English
    In: Silva fennica (Helsinki, Finland : 1967), 2021-01-01, Vol.55 (2)
    Description: Ageing and competition reduce treesâ ability to capture resources, which predisposes them to death. In this study, the effect of senescence on the survival probability of Norway spruce ( (L.) Karst.) was analysed by fitting alternative survival probability models. Different model formulations were compared in the dataset, which comprised managed and unmanaged plots in long-term forest experiments in Finland and Norway, as well as old-growth stands in Finland. Stand total age ranged from 19 to 290 years. Two models were formulated without an age variable, such that the negative coefficient for the squared stem diameter described a decreasing survival probability for the largest trees. One of the models included stand age as a separate independent variable, and three models included an interaction term between stem diameter and stand age. According to the model including stand age and its interaction with stem diameter, the survival probability curves could intersect each other in stands with a similar structure but a different mean age. Models that did not include stand age underestimated the survival rate of the largest trees in the managed stands and overestimated their survival rate in the old-growth stands. Models that included stand age produced more plausible predictions, especially for the largest trees. The results supported the hypothesis that the stand age and senescence of trees decreases the survival probability of trees, and that the ageing effect improves survival probability models for Norway spruce.Picea abies
    E-ISSN: 2242-4075
    Source: Alma/SFX Local Collection
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 9
    Language: English
    In: Annals of forest science., 2018-03, Vol.75 (1), p.1-11
    Description: Onset and cessation of radial and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in southern Finland were independent phenomena. They both contributed to the increment period duration, which was a more crucial factor defining the magnitude of annual radial and height increment. Phenology of diameter and height increment is a critical component of growth, also contributing to damage and survival of trees.We quantified annual variation in intra-annual tracheid production and height increment of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.).The number of tracheids and the day of the year for the onset and cessation of tracheid production were monitored from microcores collected repeatedly during growing seasons 2001–2012 in southern Finland. Weekly height increment was also measured in an adjacent sapling stand in 2008–2012.The first tracheids in pine were found around mid-May and in spruce a week later. The cessation of the tracheid production occurred during the last week of August for both tree species. Increment onset and cessation were independent phenomena, both contributing to the magnitude of tracheid production via increment period duration, which appeared to be a more crucial factor defining the number of tracheids. Duration of the height increment period was also related to shoot length but the connection was less tight than the link between the duration of tracheid production and the number of tracheids. A thermal threshold around 100 d.d. (degree days) was found for the onset of radial increment. No single environmental factor triggered the cessation of tracheid production, but in some years, soil water availability appeared to play a role.The results indicate that extending growing seasons due to the climatic warming may increase growth in the Finnish forests.
    Subject(s): Life Sciences ; Environment, general ; Wood Science & Technology ; Phenology ; Forestry ; Forestry Management ; Xylogenesis ; Tracheid ; Tree Biology ; Pinus sylvestris ; Picea abies ; Trees ; Moisture content ; Pine ; Annual variations ; Soil water ; Environmental factors ; Pine trees ; Water availability ; Critical components
    ISSN: 1286-4560
    E-ISSN: 1297-966X
    Source: Alma/SFX Local Collection
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  • 10
    Language: English
    In: Canadian journal of forest research, 2017, Vol.47 (2), p.234-245
    Description: The evaluation of process-based models (PBM) includes ascertaining their ability to produce results consistent with forest growth in the past. In this study, we parameterized and evaluated the hybrid model PipeQual with datasets containing traditional mensuration variables collected from permanent sample plots (PSP) of even-aged Norway spruce (Picea abies (L.) Karst.) stands in Finland. To initialize the model in the middle of stand development and reproduce observed changes in Norway spruce crown structure, the built-in empirical relationships of crown characteristics were made explicitly dependent on the light environment. After these modifications, the model accuracy at the whole dataset level was high, with slope values of linear regressions between the observations and simulations ranging from 0.77 to 0.99 depending on the variable. The average bias ranged between −0.72 and 0.07 m in stand dominant height, –0.68 and 0.57 cm in stand mean diameter, –2.62 and 1.92 m 2 in stand basal area, and 20 and 29 m 3 in stand total stem volume. Stand dynamics after thinning also followed reasonable closely the observed patterns. Accurate predictions illustrate the potential of the model for predicting forest stand growth and forest management effects in changing environmental conditions.
    Subject(s): growth response ; forest management effect ; growth simulation model ; modèle de simulation de la croissance ; effet de l’aménagement forestier ; réaction de la croissance ; Picea abies ; validation ; Spruce ; Forest management ; Models ; Growth (Plants) ; Growth
    ISSN: 0045-5067
    E-ISSN: 1208-6037
    Source: Academic Search Ultimate
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