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  • 1
    Language: English
    In: Journal of experimental botany, 2012-01-01, Vol.63 (8), p.3271-3277
    Description: Cambial injury has been reported to alter wood structure in broad-leaved trees. However, the duration and extension of associated anatomical changes have rarely been analysed thoroughly. A total of 18 young European ash ( L.) trees injured on the stem by a spring flood were sampled with the aim of comparing earlywood vessels and rays formed prior to and after the scarring event. Anatomical and hydraulic parameters were measured in five successive rings over one-quarter of the stem circumference. The results demonstrate that mechanical damage induces a decrease in vessel lumen size (up to 77%) and an increase in vessel number (up to 475%) and ray number (up to 115%). The presence of more earlywood vessels and rays was observed over at least three years after stem scarring. By contrast, abnormally narrow earlywood vessels mainly developed in the first ring formed after the event, increasing the thickness-to-span ratio of vessels by 94% and reducing both xylem relative conductivity and the index for xylem vulnerability to cavitation by 54% and 32%, respectively. These vessels accumulated in radial groups in a 30° sector immediately adjacent to the wound, raising the vessel grouping index by 28%. The wound-induced anatomical changes in wood structure express the functional need of trees to improve xylem hydraulic safety and mechanical strength at the expense of water transport. Xylem hydraulic efficiency was restored in one year, while xylem mechanical reinforcement and resistance to cavitation and decay lasted over several years.
    Subject(s): Trees ; Callus ; Xylem ; Wood ; Hydraulics ; Plant tissues ; Earlywood ; Wood structure ; Anatomy ; Growth rings ; RESEARCH PAPER ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; Plant physiology and development ; Forestry ; Organ Size ; Wood - anatomy & histology ; Analysis of Variance ; Time Factors ; Cambium - anatomy & histology ; Trees - anatomy & histology ; Index Medicus
    ISSN: 0022-0957
    E-ISSN: 1460-2431
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 2
    Language: English
    In: Trees (Berlin, West), 2013-06, Vol.27 (3), p.485-496
    Description: Thanks to acclimation, trees overcome environmental changes and endure for centuries. The anatomy of water conducting cells is an important factor determining plant success. Forming cells are coupled with the environment and their properties are naturally archived in the wood. Its variability across tree rings can thus provide a retrospective of plant’s hydraulic adjustments. In this work, we measured lumen and wall thickness of tracheids along tree-rings to explore how trees regulate their conducting system under variable plant-water conditions. Tracheids were measured along 51 dated rings of five mature Larix decidua and Picea abies trees from a low elevation site. Anatomical-based chronologies of annual growth performance, hydraulic conductance and safety, and construction costs were built. Similarities among chronologies and the relation to monthly climate data were analyzed. Most parameters displayed high annual plasticity which was partly coherent among trees and mostly associated with radial growth. In general, summer drought reduced growth and potential hydraulic conductivity of the forming ring, and increased hydraulic safety and construction costs. To evaluate the functional relevance of the annual acclimation, the conductivity of the forming ring relative to the entire sapwood needs to be assessed.
    Subject(s): Life Sciences ; Plant Pathology ; Plant Anatomy/Development ; Tree-ring anatomy ; Larix decidua ; Forestry ; Plant-water relations ; Agriculture ; Plant Physiology ; Plant Sciences ; Picea abies ; Tracheid-cell chronologies ; Climate ; Analysis ; Hydrogeology
    ISSN: 0931-1890
    E-ISSN: 1432-2285
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
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  • 3
    Language: English
    In: Ecography (Copenhagen), 2020-09, Vol.43 (9), p.1386-1399
    Description: Tree growth is an indicator of tree vitality and its temporal variability is linked to species resilience to environmental changes. Second‐order statistics that quantify the cross‐scale temporal variability of ecophysiological time series (statistical memory) could provide novel insights into species resilience. Species with high statistical memory in their tree growth may be more affected by disturbances, resulting in lower overall resilience and higher vulnerability to environmental changes. Here, we assessed the statistical memory, as quantified with the decay in standard deviation with increasing time scale, in tree water use and growth of co‐occurring European larch Larix decidua and Norway spruce Picea abies along an elevational gradient in the Swiss Alps using measurements of stem radius changes, sap flow and tree‐ring widths. Local‐scale interspecific differences between the two conifers were further explored at the European scale using data from the International Tree‐Ring Data Bank. Across the analysed elevational gradient, tree water use showed steeper variability decay with increasing time scale than tree growth, with no significant interspecific differences, highlighting stronger statistical memory in tree growth processes. Moreover, Norway spruce displayed slower decay in growth variability with increasing time scale (higher statistical memory) than European larch; a pattern that was also consistent at the European scale. The higher statistical memory in tree growth of Norway spruce in comparison to European larch is indicative of lower resilience of the former in comparison to the latter, and could potentially explain the occurrence of European larch at higher elevations at the Alpine treeline. Single metrics of resilience cannot often summarize the multifaceted aspects of ecosystem functioning, thus, second‐order statistics that quantify the strength of statistical memory in ecophysiological time series could complement existing resilience indicators, facilitating the assessment of how environmental changes impact forest growth trajectories and ecosystem services.
    Subject(s): temporal variability ; tree hydraulics and growth ; Picea abies (L) Karst ; forest resilience ; Larix decidua Mill ; tree-ring widths ; Water ; Environmental aspects ; Water use ; Growth ; Analysis
    ISSN: 0906-7590
    E-ISSN: 1600-0587
    Source: Directory of Open Access Journals
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: Polar biology, 2013-09, Vol.36 (9), p.1305-1318
    Description: Arctic ecosystems are important carbon sinks. Increasing temperatures in these regions might stimulate soil carbon release. Evidence suggests that deciduous shrubs might counteract these carbon losses because they positively respond to increasing temperature, but their role in ecosystem carbon budgets remains uncertain. Many studies dealing with large-scale tundra greening and carbon sequestration in relation to increasing temperature have usually based their estimations on the aboveground components, but very little is known about belowground growth. In this context, annual rings can provide a retrospective insight into intra-plant temperature responses and seasonal growth allocation. This study presents a 70-year-long and annually resolved intra-plant analysis of ring width and missing ring distribution from a comprehensive serial sectioning, including 142 cross-sections and the measurements of 471 radii from ten Salix polaris Wahlenb. dwarf shrubs growing in the high Arctic on Svalbard. Results indicate a high intra-plant and inter-annual growth variation, characterized by a high proportion of partially (13.6 %) and completely (11.2 %) missing rings. The annual growth and the frequency of completely missing rings were evenly distributed inside the plant and mainly controlled by summer temperatures. Radial growth in the belowground parts appeared to be proportionally higher during long and warm summers and lower in cold early growing seasons than in the aboveground parts. The results reveal a diverging allocation between aboveground and belowground growth depending on the climatic conditions. Favorable years promoted root allocation since root radial growth occurs after aboveground growth. The observed belowground responses suggest that shrub carbon allocation might be higher than estimated only from the aboveground compartments.
    Subject(s): Life Sciences ; Serial sectioning ; Microbiology ; Zoology ; Growth allocation ; Missing ring ; Intra-plant growth ; Annual rings ; Ecology ; Oceanography ; Arctic ; Plant Sciences ; Fundamental and applied biological sciences. Psychology ; Biological and medical sciences ; Synecology ; Animal and plant ecology ; Particular ecosystems ; Animal, plant and microbial ecology ; Soils ; Analysis ; Carbon content
    ISSN: 0722-4060
    E-ISSN: 1432-2056
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Oecologia, 2013-12-01, Vol.173 (4), p.1587-1600
    Description: Environment and genetics combine to influence tree growth and should therefore be jointly considered when evaluating forest responses in a warming climate. Here, we combine dendroclimatology and population genetic approaches with the aim of attributing climatic influences on growth of European larch (Larix decidua) and Norway spruce (Picea abies). Increment cores and genomic DNA samples were collected from populations along a ~900-m elevational transect where the air temperature gradient encompasses a ~4 °C temperature difference. We found that low genetic differentiation among populations indicates gene flow is high, suggesting that migration rate is high enough to counteract the selective pressures of local environmental variation. We observed lower growth rates towards higher elevations and a transition from negative to positive correlations with growing season temperature upward along the elevational transect. With increasing elevation there was also a clear increase in the explained variance of growth due to summer temperatures. Comparisons between climate sensitivity patterns observed along this elevational transect with those from Larix and Picea sites distributed across the Alps reveal good agreement, and suggest that tree-ring width (TRW) variations are more climate-driven than genetics-driven at regional and larger scales. We conclude that elevational transects are an extremely valuable platform for understanding climatic-driven changes over time and can be especially powerful when working within an assessed genetic framework.
    Subject(s): Growing seasons ; Climate change ; Dendroclimatology ; Gene flow ; Tree growth ; Genetic variation ; Correlations ; Climate models ; GLOBAL CHANGE ECOLOGY ; Population genetics ; Growth rings ; Life Sciences ; Alps ; Climate impact ; Forest productivity ; Ecology ; Plant Sciences ; Dendrochronology ; Fundamental and applied biological sciences. Psychology ; General forest ecology ; General aspects ; Animal, plant and microbial ecology ; Forestry ; Biological and medical sciences ; Animal and plant ecology ; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology ; Genetics, Population ; Climate ; Temperature ; Gene Flow ; Trees - growth & development ; Sequence Analysis, DNA ; Switzerland ; Larix - genetics ; Picea - growth & development ; Picea - genetics ; Larix - growth & development ; Seasons ; DNA, Plant - genetics ; Altitude ; Trees - genetics ; Climate sensitivity ; Growth ; Analysis ; DNA ; Archaeological dating ; Genetics ; Index Medicus
    ISSN: 0029-8549
    E-ISSN: 1432-1939
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 6
    Language: English
    In: Global change biology, 2019-11, Vol.25 (11), p.3781-3792
    Description: Extreme climate events (ECEs) such as severe droughts, heat waves, and late spring frosts are rare but exert a paramount role in shaping tree species distributions. The frequency of such ECEs is expected to increase with climate warming, threatening the sustainability of temperate forests. Here, we analyzed 2,844 tree‐ring width series of five dominant European tree species from 104 Swiss sites ranging from 400 to 2,200 m a.s.l. for the period 1930–2016. We found that (a) the broadleaved oak and beech are sensitive to late frosts that strongly reduce current year growth; however, tree growth is highly resilient and fully recovers within 2 years; (b) radial growth of the conifers larch and spruce is strongly and enduringly reduced by spring droughts—these species are the least resistant and resilient to droughts; (c) oak, silver fir, and to a lower extent beech, show higher resistance and resilience to spring droughts and seem therefore better adapted to the future climate. Our results allow a robust comparison of the tree growth responses to drought and spring frost across large climatic gradients and provide striking evidence that the growth of some of the most abundant and economically important European tree species will be increasingly limited by climate warming. These results could serve for supporting species selection to maintain the sustainability of forest ecosystem services under the expected increase in ECEs. There is an urgent need to assess the specific responses of trees to both drought and spring frost to provide solid bases for decision‐making regarding the selection of tree species matching the ongoing environmental change. Using tree‐ring width series from 2,844 trees from 104 Swiss sites ranging from 400 to 2,200 m a.s.l. for the period 1930–2016, we found strong disparities in the species resistance and resilience to extreme droughts and spring frosts. Oak, fir, and to a lower extent beech could moderately cope with severe droughts whereas spruce and larch only poorly resist and recover after such events.
    Subject(s): dendrochronology ; extreme climatic events ; growing degree‐days ; tree‐ring width ; climatic water balance ; climate warming ; tree phenology ; frost risk ; Trees ; Fagus ; Forests ; Climate Change ; Droughts ; Ecosystem ; Water balance (Hydrology) ; Ecosystems ; Analysis ; Forest ecology ; Archaeological dating ; Index Medicus ; Biodiversity and Ecology ; Environmental Sciences ; Global Changes
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 7
    Language: English
    In: Global change biology, 2015-05, Vol.21 (5), p.2005-2021
    Description: Responses of alpine tree line ecosystems to increasing atmospheric CO2 concentrations and global warming are poorly understood. We used an experiment at the Swiss tree line to investigate changes in vegetation biomass after 9 years of free air CO2 enrichment (+200 ppm; 2001–2009) and 6 years of soil warming (+4 °C; 2007–2012). The study contained two key tree line species, Larix decidua and Pinus uncinata, both approximately 40 years old, growing in heath vegetation dominated by dwarf shrubs. In 2012, we harvested and measured biomass of all trees (including root systems), above‐ground understorey vegetation and fine roots. Overall, soil warming had clearer effects on plant biomass than CO2 enrichment, and there were no interactive effects between treatments. Total plant biomass increased in warmed plots containing Pinus but not in those with Larix. This response was driven by changes in tree mass (+50%), which contributed an average of 84% (5.7 kg m−2) of total plant mass. Pinus coarse root mass was especially enhanced by warming (+100%), yielding an increased root mass fraction. Elevated CO2 led to an increased relative growth rate of Larix stem basal area but no change in the final biomass of either tree species. Total understorey above‐ground mass was not altered by soil warming or elevated CO2. However, Vaccinium myrtillus mass increased with both treatments, graminoid mass declined with warming, and forb and nonvascular plant (moss and lichen) mass decreased with both treatments. Fine roots showed a substantial reduction under soil warming (−40% for all roots 〈2 mm in diameter at 0–20 cm soil depth) but no change with CO2 enrichment. Our findings suggest that enhanced overall productivity and shifts in biomass allocation will occur at the tree line, particularly with global warming. However, individual species and functional groups will respond differently to these environmental changes, with consequences for ecosystem structure and functioning.
    Subject(s): mountain pine ; dwarf shrub ; global change ; Larix decidua ; Pinus uncinata ; European larch ; free air CO2 enrichment ; Pinus - growth & development ; Global Warming ; Temperature ; Species Specificity ; Soil ; Biomass ; Larix - growth & development ; Models, Statistical ; Carbon Dioxide - analysis ; Carbon Dioxide - pharmacology ; Switzerland ; Tundra ; Ecosystem components ; Global temperature changes ; Soil heating ; Alpine ecosystems ; Mountain ecology ; Index Medicus
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 8
    Language: English
    In: Frontiers in plant science, 2018, Vol.9, p.1144-1144
    Description: Wood formation allows trees to adjust in a changing climate. Understanding what determine its adjustment is crucial to evaluate impacts of climatic changes on trees and forests growth. Despite efforts to characterize wood formation, little is known on its impact on the xylem cellular structure. In this study we apply the Vaganov-Shashkin model to generate synthetic tracheidograms and verify its use to investigate the formation of intra-annual density fluctuations (IADF), one of the most frequent climate tree-ring markers in drought-exposed sites. Results indicate that the model can produce realistic tracheidograms, except for narrow rings (〈1 mm), when cambial activity stops due to an excess of drought or a lack of growth vigor. These observations suggest that IADFs are caused by a release of drought limitation to cells formation in the first half of the growing season, but that narrow rings are indicators of an even more extreme and persistent water stress. Taking the example of IADFs formation, this study demonstrated that the Vaganov-Shashkin model is a useful tool to study the climatic impact on tree-ring structures. The ability to produce synthetic tracheidogram represents an unavoidable step to link climate to tree growth and xylem functioning under future scenarios.
    Subject(s): Scots pine ; Tree-rings ; Droughts ; United States ; Analysis ; Physiological aspects ; Steppes ; Influence ; Research ; tracheid ; Plant Science ; VS-oscilloscope ; tracheidogram ; cambial activity ; South Siberia ; process-based Vaganov-Shashkin model ; cell size
    ISSN: 1664-462X
    E-ISSN: 1664-462X
    Source: PubMed Central
    Source: Directory of Open Access Journals
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 9
    Language: English
    In: Global change biology, 2021-01, Vol.27 (1), p.121-135
    Description: Wood growth constitutes the main process for long‐term atmospheric carbon sequestration in vegetation. However, our understanding of the process of wood growth and its response to environmental drivers is limited. Current dynamic global vegetation models (DGVMs) are mainly photosynthesis‐driven and thus do not explicitly include a direct environmental effect on tree growth. However, physiological evidence suggests that, to realistically model vegetation carbon allocation under increased climatic stressors, it is crucial to treat growth responses independently from photosynthesis. A plausible growth response function suitable for global simulations in DGVMs has been lacking. Here, we present the first soil water‐growth response function and parameter range for deciduous and evergreen conifers. The response curve was calibrated against European larch and Norway spruce in a dry temperate forest in the Swiss Alps. We present a new data‐driven approach based on a combination of tree ring width (TRW) records, growing season length and simulated subdaily soil hydrology to parameterize ring width increment simulations. We found that a simple linear response function, with an intercept at zero moisture stress, used in growth simulations reproduced 62.3% and 59.4% of observed TRW variability for larch and spruce respectively and, importantly, the response function slope was much steeper than literature values for soil moisture effects on photosynthesis and stomatal conductance. Specifically, we found stem growth stops at soil moisture potentials of −0.47 MPa for larch and −0.66 MPa for spruce, whereas photosynthesis in trees continues down to −1.2 MPa or lower, depending on species and measurement method. These results are strong evidence that the response functions of source and sink processes are indeed very different in trees, and need to be considered separately to correctly assess vegetation responses to environmental change. The results provide a parameterization for the explicit representation of growth responses to soil water in vegetation models. We have developed a novel data‐driven method to examine soil moisture‐growth relationships in evergreen trees. We find that growth ceases at soil water levels that still allow significant photosynthesis. These results are strong evidence that the response functions of source and sink processes are very different in trees, and should therefore be modelled as separate processes when studying terrestrial carbon cycling.
    Subject(s): vegetation modelling ; xylogenesis ; Picea abies (L.) H. Karst ; soil moisture ; soil moisture growth response ; tree growth ; tree physiology ; Larix decidua Mill ; source–sink ; tree rings ; Hydrology ; Dendroclimatology ; Growth ; Analysis ; Physiological aspects ; Models ; Photosynthesis ; Carbon cycle (Biogeochemistry) ; Index Medicus
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 10
    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 ; Index Medicus ; Life Sciences ; Vegetal Biology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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