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  • 1
    Language: English
    In: Oecologia, 2007-05-01, Vol.152 (1), p.1-12
    Description: Temperature is the most important factor affecting growth at high altitudes. As trees use much of the allocated carbon gained from photosynthesis to produce branches and stems, information on the timing and dynamics of secondary wood growth is crucial to assessing temperature thresholds for xylogenesis. We have carried out histological analyses to determine cambial activity and xylem cell differentiation in conifers growing at the treeline on the eastern Alps in two sites during 2002- 2004 with the aim of linking the growth process with temperature and, consequently, of defining thresholds for xylogenesis. Cambial activity occurred from May to July-August and cell differentiation from May-June to September-October. The earliest start of radial enlargement was observed in stone pine in mid-May, while Norway spruce was the last species to begin tracheid differentiation. The duration of wood formation varied from 90 to 137 days, depending on year and site, with no difference between species. Longer durations were observed in trees on the south-facing site because of the earlier onset and later ending of cell production and differentiation. The threshold temperatures at which xylogenesis had a 0.5 probability of being active were calculated by logistic regressions. Xylogenesis was active when the mean daily air temperature was 5.6-8.5°C and mean stem temperature was 7.2-9°C. The similar thresholds among all trees suggested the existence of thermal limits in wood formation that correspond with temperatures of 6-8°C that are supposed to limit growth at the treeline. Different soil temperature thresholds between sites indicated that soil temperature may not be the main factor limiting xylogenesis. This study represents the first attempt to define a threshold through comparative assessment of xylem growth and tissue temperatures in stem meristems at high altitudes.
    Subject(s): Trees ; Cell growth ; Xylem ; Tree growth ; Tracheids ; Timberlines ; Cell differentiation ; Ecophysiology ; Stems ; Growth rings ; Soil temperature ; Life Sciences ; Alps ; Tree ring ; Treeline ; Ecology ; Plant Sciences ; Cambial activity ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; General aspects ; Animal and plant ecology ; Animal, plant and microbial ecology ; Temperature ; Xylem - cytology ; Coniferophyta - growth & development ; Periodicity ; Xylem - growth & development ; Cell Differentiation ; Seasons ; Wood - growth & development ; Altitude
    ISSN: 0029-8549
    E-ISSN: 1432-1939
    Source: JSTOR Life Sciences
    Source: JSTOR Ecology & Botany II
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Journal of experimental botany, 2012-01-01, Vol.63 (5), p.2117-2126
    Description: Although habitually considered as a whole, xylogenesis is a complex process of division and maturation of a pool of cells where the relationship between the phenological phases generating such a growth pattern remains essentially unknown. This study investigated the causal relationships in cambium phenology of black spruce [ (Mill.) BSP] monitored for 8 years on four sites of the boreal forest of Quebec, Canada. The dependency links connecting the timing of xylem cell differentiation and cell production were defined and the resulting causal model was analysed with d-sep tests and generalized mixed models with repeated measurements, and tested with Fisher’s C statistics to determine whether and how causality propagates through the measured variables. The higher correlations were observed between the dates of emergence of the first developing cells and between the ending of the differentiation phases, while the number of cells was significantly correlated with all phenological phases. The model with eight dependency links was statistically valid for explaining the causes and correlations between the dynamics of cambium phenology. Causal modelling suggested that the phenological phases involved in xylogenesis are closely interconnected by complex relationships of cause and effect, with the onset of cell differentiation being the main factor directly or indirectly triggering all successive phases of xylem maturation.
    Subject(s): Trees ; Cell growth ; Xylem ; Lignification ; Tracheids ; Cell walls ; Phenology ; Cambium ; Cellular differentiation ; Growth rings ; RESEARCH PAPER ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; Plant physiology and development ; Forestry ; Climate ; Picea - physiology ; Quebec ; Cambium - growth & development ; Xylem - cytology ; Models, Biological ; Picea - growth & development ; Cell Wall - metabolism ; Plant Stems - cytology ; Xylem - growth & development ; Cell Differentiation ; Cambium - cytology ; Wood - growth & development ; Picea - cytology ; Plant Stems - growth & development ; xylogenesis ; cell production ; d-sep test ; Research Papers ; cell differentiation ; secondary wall formation ; Causal modelling ; Picea mariana
    ISSN: 0022-0957
    E-ISSN: 1460-2431
    Source: JSTOR Ecology & Botany II
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
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  • 3
    Language: English
    In: The New phytologist, 2008-01-01, Vol.177 (1), p.199-208
    Description: • Neither anatomical change nor physiological abnormalities have been observed in the cambia of older trees. However, different sensitivity and period of significant responses to climate suggest the existence of some age-related change in the patterns of cambial activity and/or wood cell formation. • Here, weekly cambial activity and timing and duration of xylem cell enlargement and wall thickening were compared in adult (50-80 yr) and old (200-350 yr) trees of Larix decidua, Pinus cembra and Picea abies at the Alpine timberline during 2004 and 2005. • Timings and durations of xylogenesis differed between adult and old trees, with 2-3 wk shorter cambial activity found in the latter. The delayed onset of cambium division and lower cell production in old trees, with respect to adult trees, led to reductions of 15-20% in the overall duration of xylem differentiation. • These results demonstrate that cambial dynamics change during the tree lifespan and that the time window of tree-ring production shortens with age. Variations in the period of xylem growth may be the cause of age-dependent responses to climate. The observed shorter xylogenesis in older plants at the Alpine timberline could be related to a size effect and not just to age per se.
    Subject(s): Trees ; Dendroclimatology ; Xylem ; Tracheids ; Cell walls ; Timberlines ; Pine trees ; Cambium ; Tree age ; Growth rings ; Alps ; cell differentiation ; cambial activity ; wood formation ; timberline ; uniformitarian principle ; tree age ; tree ring ; Xylem - cytology ; Aging - physiology ; Time Factors ; Xylem - metabolism ; Ecosystem ; Italy ; Pinaceae - metabolism ; Altitude
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 4
    Language: English
    In: Plant physiology (Bethesda), 2016-04-01, Vol.170 (4), p.2072-2084
    Description: Nonstructural carbohydrates (NSCs) play a crucial role in xylem formation and represent, with water, the main constraint to plant growth. We assessed the relationships between xylogenesis and NSCs in order to (1) verify the variance explained by NSCs and (2) determine the influence of intrinsic (tissue supplying carbon) and extrinsic (water availability and temperature) factors. During 2 years, wood formation was monitored in saplings of black spruce ( ) subjected to a dry period of about 1 month in June and exposed to different temperature treatments in a greenhouse. In parallel, NSC concentrations were determined by extracting the sugar compounds from two tissues (cambium and inner xylem), both potentially supplying carbon for wood formation. A mixed-effect model was used to assess and quantify the potential relationships. Total xylem cells, illustrating meristematic activity, were modeled as a function of water, sucrose, and D-pinitol (conditional ² of 0.79). Water availability was ranked as the most important factor explaining total xylem cell production, while the contribution of carbon was lower. Cambium stopped dividing under water deficit, probably to limit the number of cells remaining in differentiation without an adequate amount of water. By contrast, carbon factors were ranked as most important in explaining the variation in living cells (conditional ² of 0.49), highlighting the functional needs during xylem development, followed by the tissue supplying the NSCs (cambium) and water availability. This study precisely demonstrates the role of carbon and water in structural growth expressed as meristematic activity and tissue formation.
    Subject(s): ECOPHYSIOLOGY AND SUSTAINABILITY ; Carbon - metabolism ; Temperature ; Solubility ; Water - metabolism ; Wood - cytology ; Trees - growth & development ; Cambium - metabolism ; Xylem - metabolism ; Models, Biological ; Picea - growth & development ; Carbohydrates - analysis ; Cell Differentiation ; Picea - metabolism ; Wood - growth & development ; Picea - cytology ; Spruce ; Physiological aspects ; Carbohydrate metabolism ; Plant-water relationships ; Observations
    ISSN: 0032-0889
    E-ISSN: 1532-2548
    Source: American Society of Plant Biologists
    Source: JSTOR Life Sciences
    Source: Hellenic Academic Libraries Link
    Source: JSTOR Ecology & Botany II
    Source: PubMed Central
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  • 5
    Language: English
    In: The New phytologist, 2021-05, Vol.230 (3), p.957-971
    Description: Summary Wood density is the product of carbon allocation for structural growth and reflects the trade‐off between mechanical support and water conductivity. We tested a conceptual framework based on the assumption that micro‐density depends on direct and indirect relationships with endogenous and exogenous factors. The dynamics of wood formation, including timings and rates of cell division, cell enlargement, and secondary wall deposition, were assessed from microcores collected weekly between 2002 and 2016 from five black spruce stands located along a latitudinal gradient in Quebec, Canada. Cell anatomy and micro‐density were recorded by anatomical analyses and X‐ray measurements. Our structural equation model explained 80% of micro‐density variation within the tree‐ring with direct effects of wall thickness (σ = 0.61), cell diameter (σ = −0.51), and photoperiod (σ = −0.26). Wood formation dynamics had an indirect effect on micro‐density. Micro‐density increased under longer periods of cell‐wall deposition and shorter durations of enlargement. Our results fill a critical gap in understanding the relationships underlying micro‐density variation in conifers. We demonstrated that short‐term responses to environmental variations could be overridden by plastic responses that modulate cell differentiation. Our results point to wood formation dynamics as a reliable predictor of carbon allocation in trees.
    Subject(s): cell‐wall thickness ; structural equation modelling ; temperature ; soil water content ; cell diameter ; secondary wall deposition ; photoperiod ; cell enlargement ; Trees ; Canada ; Xylem ; Wood ; Picea ; Quebec ; Cell differentiation ; Specific gravity ; Soil moisture ; Analysis ; Electric properties ; Life Sciences ; Plants genetics ; Populations and Evolution ; Agricultural sciences ; Phytopathology and phytopharmacy ; Plant breeding ; Genetics ; Silviculture, forestry ; Vegetal Biology
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 6
    Language: English
    In: The New phytologist, 2014-08-01, Vol.203 (3), p.831-841
    Description: Primary (budburst, foliage and shoot) growth and secondary (cambium and xylem) growth of plants play a vital role in sequestering atmospheric carbon. However, their potential relationships have never been mathematically quantified and the underlying physiological mechanisms are unclear. We monitored primary and secondary growth in and on a weekly basis from 2010 to 2013 at four sites over an altitudinal gradient (25–900 m) in the eastern Canadian boreal forest. We determined the timings of onset and termination through the fitted functions and their first derivative. We quantified the potential relationships between primary growth and secondary growth using the mixed-effects model. We found that xylem formation of boreal conifers can be modeled as a function of cambium activity, bud phenology, and shoot and needle growth, as well as species- and site-specific factors. Our model reveals that there may be an optimal mechanism to simultaneously allocate the photosynthetic products and stored nonstructural carbon to growth of different organs at different times in the growing season. This mathematical link can bridge phenological modeling, forest ecosystem productivity and carbon cycle modeling, which will certainly contribute to an improved prediction of ecosystem productivity and carbon equilibrium.
    Subject(s): Full papers ; Cell growth ; Xylem ; Ecosystem models ; Plant growth ; Mathematical growth ; Phenology ; Climate models ; Cambium ; Forest growth ; Modeling ; ecosystem ; boreal forest ; mixed‐effects model ; phenology ; xylem formation ; tree growth ; primary growth ; secondary growth ; Xylem - cytology ; Time Factors ; Models, Biological ; Cell Count ; Quebec ; Xylem - growth & development ; Trees - growth & development ; Organ Specificity ; Cambium - physiology ; Physiological aspects ; Photosynthesis ; Growth ; Analysis ; Carbon cycle (Biogeochemistry) ; Forest ecology
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 7
    Language: English
    In: Global change biology, 2020-04, Vol.26 (4), p.2072-2080
    Description: Climate change is altering phenology; however, the magnitude of this change varies among taxa. Compared with phenological mismatch between plants and herbivores, synchronization due to climate has been less explored, despite its potential implications for trophic interactions. The earlier budburst induced by defoliation is a phenological strategy for plants against herbivores. Here, we tested whether warming can counteract defoliation‐induced mismatch by increasing herbivore‐plant phenological synchrony. We compared the larval phenology of spruce budworm and budburst in balsam fir, black spruce, and white spruce saplings subjected to defoliation in a controlled environment at temperatures of 12, 17, and 22°C. Budburst in defoliated saplings occurred 6–24 days earlier than in the controls, thus mismatching needle development from larval feeding. This mismatch decreased to only 3–7 days, however, when temperatures warmed by 5 and 10°C, leading to a resynchronization of the host with spruce budworm larvae. The increasing synchrony under warming counteracts the defoliation‐induced mismatch, disrupting trophic interactions and energy flow between forest ecosystem and insect populations. Our results suggest that the predicted warming may improve food quality and provide better growth conditions for larval development, thus promoting longer or more intense insect outbreaks in the future. Climate change is altering phenology; however, the magnitude of this change varies among taxa. The earlier budburst induced by defoliation is a phenological strategy for plants against herbivores. The increasing synchrony between plants and herbivores under warming counteracts the defoliation‐induced mismatch, disrupting trophic interactions and energy flow between forest ecosystem and insect populations.
    Subject(s): outbreak ; budburst ; global warming ; Choristoneura fumiferana ; boreal forest ; phenology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Trees (Berlin, West), 2015-02, Vol.29 (1), p.25-34
    Description: Spring temperature is a major limiting factor at the beginning of the growing season, the timing of growth initiation can increase by about 7 days/°C. During the growing season, impacts of climate variables on radial growth are similar along an altitudinal gradient. Altitude is considered as an important factor affecting tree growth in mountain forest ecosystems. In this paper, the results of a 2-year field study along an altitudinal gradient in the cold and arid central Qilian Mountains, northwestern China, are reported. Twelve Qilian juniper trees (Sabina przewalskii Kom.) were monitored with high-resolution dendrometers at three altitudes ranging from 2,865 to 3,550 m. At each altitude, a local weather station was installed close to the studied trees. We identified correlations between intra-annual growth patterns derived from the Gompertz equation with local air temperature and precipitation data. The timing of growth initiation became earlier and the growing season duration increased with decreasing altitude. The onset of radial growth occurred between early May and early June, and the growing season terminated between mid-July and late August, resulting in a growing season duration that decreased from 107 to 41 days as elevation increased. June is the most important growth period at each altitude. Spring temperature, which is strongly associated with elevation, is a critical factor determining the initiation of radial growth. The timing of growth initiation was delayed by 3–4 days per 100 m elevation. When associated with the modeled altitudinal spring temperature lapse rate of −0.48 °C/100 m, the onset of the growing season increased by about 7 days/°C. However, during the growing season, daily stem radial increments showed a positive correlation with precipitation and a negative correlation with daily maximum air temperature at all altitudes. Our study provides new data revealing the basic growth processes of Qilian juniper trees and provides significant information to quantify the responses of tree growth to future global warming.
    Subject(s): Life Sciences ; Plant Pathology ; Plant Anatomy/Development ; Dendrometer ; Stem radial increment ; Altitudinal gradient ; Qilian Mountains ; Forestry ; Agriculture ; Plant Physiology ; Plant Sciences ; Sabina przewalskii Kom ; Weather ; Precipitation (Meteorology) ; Arid regions ; Ecosystems ; Analysis ; Mountain ecology
    ISSN: 0931-1890
    E-ISSN: 1432-2285
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
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  • 9
    Language: English
    In: Global change biology, 2011-01, Vol.17 (1), p.614-625
    Description: In the next century, the boreal ecosystems are projected to experience greater rates of warming than most other regions of the world. As the boreal forest constitutes a reservoir of trees of huge ecological importance and only partially known economic potential, any possible climate‐related change in plant growth and dynamics has to be promptly predicted and evaluated. A model for assessing xylem phenology in black spruce [Picea mariana (Mill.) B.S.P.] using daily temperatures and thermal thresholds was defined and applied to predict changes in onset, ending and duration of xylem growth under different warming scenarios with temperatures rising by up to 3 °C. This was achieved by collecting and analyzing a dataset obtained from a 7‐year monitoring of cambium phenology and wood formation on a weekly time‐scale in trees growing in four sites at different latitudes and altitudes in the Saguenay‐Lac‐Saint‐Jean region (Quebec, Canada). The onset of xylem growth occurred between mid‐May and early June while the end ranged between mid‐September and early October, resulting in a growing season of 101–141 days. The model predicted longer duration of xylem growth at higher temperatures, with an increase of 8–11 days/ °C, because of an earlier onset and later ending of growth. With an increase of 3 °C in the mean temperature during the year, the duration of xylem growth changed on average from 125 to 160 days. The predicted changes in cambial phenology could significantly affect future wood production of the boreal ecosystems.
    Subject(s): xylogenesis ; microcoring ; cell differentiation ; cambium ; Picea mariana ; boreal forest ; Fundamental and applied biological sciences. Psychology ; General aspects ; Animal, plant and microbial ecology ; Exact sciences and technology ; Earth, ocean, space ; External geophysics ; Biological and medical sciences ; Climatology. Bioclimatology. Climate change ; Animal and plant ecology ; Meteorology ; Ecosystems ; Climate ; Analysis
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 10
    Language: English
    In: Annals of forest science., 2019-09, Vol.76 (3), p.1-18
    Description: High-resolution analysis of stem radius variation can quantify the impact of warming and drought on stem water balance and stem growth in black spruce [ Picea mariana (Mill.) B.S.P.)]. Drought affected plant water status and stem growth. However, warming affects the components of the circadian stem cycle differently if the impacts occur in the daytime or nighttime. The interactive effect of abiotic stresses had less impact on the circadian stem cycle than when the stresses occurred independently. Warming and recent droughts in boreal regions reflect the multiple dimensions of climate change. How these climate-related stresses will affect the stem growth of trees remains to be described. Plant water relations can detect the dynamics of stem depletion and replenishment under conditions of climate-forced stress.This study aimed to verify the impacts of a combination of asynchronous warming (nighttime versus daytime warming) and drought on stem water balance and stem growth in black spruce [Picea mariana (Mill.) B.S.P.)].We investigated the water status and variations in stem radius of black spruce saplings growing in a controlled environment from May through August. We grew four-year-old saplings in warmer conditions either during the day (DW) or night (NW) at temperatures ca. 6 °C warmer than the ambient air temperature (CT). We then simulated a one-month drought in June. Automatic point dendrometers provided a high-resolution analysis of variations in stem radius, and we also monitored leaf water potentials and volumetric soil water content during the entire experimental period.We detected significant reductions in stem radius variation under water deficit conditions. In the daytime warming scenario, we observed a significant increase in the duration of contraction and a decrease in expansion of the stems. The amplitude of this contraction and expansion was reduced under the nighttime warming conditions. The main effect of warming was to enhance drought stress by accelerating soil water depletion. Changes in predawn water potential drove the duration of stem circadian cycles under conditions of daytime warming, whereas irreversible growth dynamics drove these cycles under nighttime warming conditions due to the midday water potential. The interaction of night/daytime asynchronous warming and drought reduced the amplitude rather than the duration of stem contraction and expansion.Water deficit decreased stem growth during the growing season. Asymmetric warming (as a single independent treatment) affected the timing and magnitude of stem circadian cycles. Under daytime warming scenarios, the duration of contraction and expansion were regulated mainly by predawn water potential, inducing longer (shorter) durations of contraction (expansion). Under nighttime warming, the smaller amplitudes of stem contraction and expansion were associated with midday water potential. Therefore, the interaction of abiotic stresses had less of an impact on the circadian stem cycle components than when these stresses were applied independently.
    Subject(s): Life Sciences ; Environment, general ; Water status ; Wood Science & Technology ; Point dendrometer ; Water deficit ; Black spruce ; Forestry ; Forestry Management ; Saplings ; Tree Biology ; Asynchronous warming ; Life Sciences & Biomedicine ; Science & Technology ; High resolution ; Amplitudes ; Daytime ; Night ; Moisture content ; Replenishment ; Air temperature ; Water content ; Soil water ; Nonlinear response ; Drought ; Expansion ; Trees ; Circadian rhythms ; Soil stresses ; Abiotic stress ; Water balance ; Water potential ; Environmental impact ; Nighttime ; Water relations ; Climate change ; Soils ; Depletion ; Variation
    ISSN: 1286-4560
    E-ISSN: 1297-966X
    Source: Web of Science - Science Citation Index Expanded - 2019〈img src="http://exlibris-pub.s3.amazonaws.com/fromwos-v2.jpg" /〉
    Source: Alma/SFX Local Collection
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