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  • 1
    Language: English
    In: Global change biology, 2019-03, Vol.25 (3), p.1089-1105
    Description: The phenology of wood formation is a critical process to consider for predicting how trees from the temperate and boreal zones may react to climate change. Compared to leaf phenology, however, the determinism of wood phenology is still poorly known. Here, we compared for the first time three alternative ecophysiological model classes (threshold models, heat‐sum models and chilling‐influenced heat‐sum models) and an empirical model in their ability to predict the starting date of xylem cell enlargement in spring, for four major Northern Hemisphere conifers (Larix decidua, Pinus sylvestris, Picea abies and Picea mariana). We fitted models with Bayesian inference to wood phenological data collected for 220 site‐years over Europe and Canada. The chilling‐influenced heat‐sum model received most support for all the four studied species, predicting validation data with a 7.7‐day error, which is within one day of the observed data resolution. We conclude that both chilling and forcing temperatures determine the onset of wood formation in Northern Hemisphere conifers. Importantly, the chilling‐influenced heat‐sum model showed virtually no spatial bias whichever the species, despite the large environmental gradients considered. This suggests that the spring onset of wood formation is far less affected by local adaptation than by environmentally driven plasticity. In a context of climate change, we therefore expect rising winter–spring temperature to exert ambivalent effects on the spring onset of wood formation, tending to hasten it through the accumulation of forcing temperature, but imposing a higher forcing temperature requirement through the lower accumulation of chilling. A temperature sum model influenced by chilling accumulation predicts the spring onset of xylem enlargement across temperate and boreal latitudes, in four major Northern Hemisphere conifers. This model outperformed heat‐sums and threshold models. On the figure, plots per species show predicted (coloured lines) and observed (grey dots) xylem onset dates, sorted by temperatures during the January–June period. The central plot shows the species‐specific relation between chilling and forcing accumulation.
    Subject(s): chilling temperatures ; forcing temperatures ; cambium ; conifers ; phenological models ; wood phenology ; Weather forecasting ; Analysis ; Biodiversity and Ecology ; Environmental Sciences ; Global Changes
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 2
    Language: English
    In: Forests, 2018-07-11, Vol.9 (7), p.416
    Description: Wood formation is the primary biological process through which carbon is durably sequestered in woody plants, and is thus a major contributor to mitigate climate change. We analyzed the tree growth patterns of four conifer species across the Iberian Peninsula (IP) based on a dense dendrochronological network (179 sites) combined with a high resolution climate dataset. Generalized linear-mixed models were used to predict the potential tree growth of different pine species under different climate conditions considering different age classes. We found a strong age dependency of tree growth, significant variations across the climate gradients, and a significant interaction of both age and climate effects on the four species considered. Overall, Pinus halepensis was the species with the highest climate sensitivity and the highest growth rates in all age classes and across its distribution area. Due to its stronger plastic character and its potential adaptability, Pinus halepensis was demonstrated to be the most suitable species in terms of tree growth and potentiality to enhance carbon sequestration in the IP. Since its potential distribution largely exceeds its actual distribution, P. halepensis arises as a key species to cope with future climate conditions and to keep fixing carbon regardless of the climatic circumstances.
    Subject(s): dendrochronology ; Pinus nigra ; Pinus halepensis ; Generalized Linear Mixed-Effects models ; Pinus uncinata ; basal area increment ; tree-rings ; climate ; Pinus sylvestris ; age-effects
    ISSN: 1999-4907
    E-ISSN: 1999-4907
    Source: Directory of Open Access Journals
    Source: ProQuest Central
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  • 3
    Language: English
    In: Global change biology, 2018-05, Vol.24 (5), p.2143-2158
    Description: Forecasted increase drought frequency and severity may drive worldwide declines in forest productivity. Species‐level responses to a drier world are likely to be influenced by their functional traits. Here, we analyse forest resilience to drought using an extensive network of tree‐ring width data and satellite imagery. We compiled proxies of forest growth and productivity (TRWi, absolutely dated ring‐width indices; NDVI, Normalized Difference Vegetation Index) for 11 tree species and 502 forests in Spain corresponding to Mediterranean, temperate, and continental biomes. Four different components of forest resilience to drought were calculated based on TRWi and NDVI data before, during, and after four major droughts (1986, 1994–1995, 1999, and 2005), and pointed out that TRWi data were more sensitive metrics of forest resilience to drought than NDVI data. Resilience was related to both drought severity and forest composition. Evergreen gymnosperms dominating semi‐arid Mediterranean forests showed the lowest resistance to drought, but higher recovery than deciduous angiosperms dominating humid temperate forests. Moreover, semi‐arid gymnosperm forests presented a negative temporal trend in the resistance to drought, but this pattern was absent in continental and temperate forests. Although gymnosperms in dry Mediterranean forests showed a faster recovery after drought, their recovery potential could be constrained if droughts become more frequent. Conversely, angiosperms and gymnosperms inhabiting temperate and continental sites might have problems to recover after more intense droughts since they resist drought but are less able to recover afterwards. In this study, we analysed the resistance and resilience to drought of forests dominated by 11 species across wide climatic and environmental gradients in the Mediterranean basin using proxies of forest productivity (NDVI) and carbon accumulation (ring‐width indices, TRWi) and considering four extreme drought events recorded between 1980 and 2005. Our results indicate that drought intensity is a major driver of forest resilience to drought but that species inhabiting different regions present different strategies to cope with drought and thus they can respond differently to more frequent and severe droughts.
    Subject(s): normalized difference vegetation index ; forest growth ; drought stress ; resilience index ; tree‐rings ; forest productivity ; dendroecology ; Magnoliopsida - physiology ; Forests ; Time Factors ; Cycadopsida - physiology ; Droughts ; Mediterranean Region ; Spain ; Biomes ; Remote sensing ; 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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  • 4
    Language: English
    In: Frontiers in plant science, 2016-03-23, Vol.7, p.370-370
    Description: Wood formation in European beech ( Fagus sylvatica L.) and Scots pine ( Pinus sylvestris L.) was intra-annually monitored to examine plastic responses of the xylem phenology according to altitude in one of the southernmost areas of their distribution range, i.e., in the Moncayo Natural Park, Spain. The monitoring was done from 2011 to 2013 at 1180 and 1580 m a.s.l., corresponding to the lower and upper limits of European beech forest in this region. Microcores containing phloem, cambium and xylem were collected biweekly from twenty-four trees from the beginning of March to the end of November to assess the different phases of wood formation. The samples were prepared for light microscopy to observe the following phenological phases: onset and end of cell production, onset and end of secondary wall formation in xylem cells and onset of cell maturation. The temporal dynamics of wood formation widely differed among years, altitudes and tree species. For Fagus sylvatica , the onset of cambial activity varied between the first week of May and the third week of June. Cambial activity then slowed down and stopped in summer, resulting in a length of growing season of 48–75 days. In contrast, the growing season for P. sylvestris started earlier and cambium remained active in autumn, leading to a period of activity varying from 139-170 days. The intra-annual wood-formation pattern is site and species-specific. Comparison with other studies shows a clear latitudinal trend in the duration of wood formation, positive for Fagus sylvatica and negative for P. sylvestris .
    Subject(s): xylogenesis ; Plant Science ; Moncayo Natural Park ; Scots pine ; cambial activity ; European beech ; microcore ; Xylogenesis ; European Beech ; Microcore ; Cambial activity
    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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  • 5
    Language: English
    In: Trees (Berlin, West), 2014-10, Vol.28 (5), p.1267-1277
    Description: A network of 41 local tree-ring chronologies of oak (Quercus petraea and Quercus robur) in Austria, Hungary, Slovenia, Croatia and Serbia (latitudes 45.00–48.00N, longitudes 13.14–21.63E, altitudes 80–800 m a.s.l.) was constructed and used to establish common climatic signals in oak tree rings in the region. Co-variation of residual chronologies could be resumed in 11 significant principal components (PC), explaining 79 % of common variability. Three of them, PC1, PC2 and PC3, made it possible to identify similarities among the sites. PC1, significantly correlated with all 41 chronologies, indicated a common positive response to precipitation in spring and summer (March and June) and a negative response to temperature in spring and summer (April and June). PC2, significantly correlated with 12 chronologies, indicated a common positive response to precipitation especially in spring (May) and a negative one to high summer temperatures (especially in August) with a pronounced north to south gradient. PC3, significantly correlated with ten chronologies, indicated that a warm previous December and warm current September have a positive effect on tree growth, especially in the south-western part of the study area. The obtained climate–growth relationships will help to understand better the variability of oak growth, to fill palaeoclimatic gaps and to improve dendrochronological research in the region.
    Subject(s): Life Sciences ; Plant Pathology ; Plant Anatomy/Development ; Forestry ; Oak ; Quercus sp ; Agriculture ; Plant Physiology ; Plant Sciences ; Dendrochronology ; Climatic signal ; Tree-ring network ; Archaeological dating ; Precipitation (Meteorology)
    ISSN: 0931-1890
    E-ISSN: 1432-2285
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
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  • 6
    Language: English
    In: The Journal of ecology, 2020-11, Vol.108 (6), p.2473-2484
    Description: The negative impacts of drought on forest growth and productivity last for several years generating legacies, although the factors that determine why such legacies vary across sites and tree species remain unclear. We used an extensive network of tree‐ring width (RWI, ring‐width index) records of 16 tree species from 567 forests, and high‐resolution climate and normalized difference vegetation index (NDVI) datasets across Spain during the common period 1982‒2008 to test the hypothesis that climate conditions and growth features modulate legacy effects of drought on forests. Legacy effects of drought were calculated as the differences between detrended‐only RWI and NDVI series (i.e. after removing long‐term growth trends) and pre‐whitened RWI and NDVI series predicted by a model including drought intensity. Superposed Epoch Analysis (SEA) was used to estimate whether legacy effects differed from random. Finally, legacy effects were related to water balance, growth persistence and variability, and tree species identity. We found a widespread occurrence of drought legacy effects on both RWI and NDVI, but they were seldom significant. According to SEA, first‐year drought legacies were negative and different from random in 9% and 5% of the RWI and NDVI series respectively. The number of significant second‐ and third‐year legacies was substantially lower. Differences between RWI and NDVI legacies indicate that canopy greenness and radial growth responses to drought are decoupled. We found variations in legacies between tree species with gymnosperms presenting larger first‐year drought legacies than angiosperms, which were exposed to less severe droughts. Greater growth variability can explain the presence of first‐year RWI legacies in gymnosperms from dry sites despite that the relationship between growth variability and legacies was complex. Synthesis. Accounting for species and site responses to drought provides a better understanding of the magnitude and duration of drought legacies on forest growth and productivity. Despite the widespread occurrence of growth reductions in the years during and after drought occurrence, significant legacies were not very common, mostly lasted one year, and were more widespread in gymnosperms. These are relevant factors to be considered in the future when studying the consequences of drought on forest productivity and tree growth. Legacy effects of drought on tree growth (RWI, ring‐width indices) and forest productivity (NDVI) vary between tree species. Drought legacies are more common for gymnosperms than for angiosperms and usually last for one year. Growth variability partially explains the variation in drought legacies between species despite the fact that this relationship is complex and species‐specific.
    Subject(s): drought intensity ; SPEI ; tree‐rings ; growth variability ; dendroecology ; global change ecology ; NDVI ; Water balance (Hydrology) ; Coniferous forests ; Droughts ; Growth ; Analysis
    ISSN: 0022-0477
    E-ISSN: 1365-2745
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 7
    Language: English
    In: Frontiers in plant science, 2016, Vol.7, p.1923-1923
    Description: To understand better the adaptation strategies of intra-annual radial growth in and to local environmental conditions, we examined the seasonal rhythm of cambial activity and cell differentiation at tissue and cellular levels. Two contrasting sites differing in temperature and amount of precipitation were selected for each species, one typical for their growth and the other represented border climatic conditions, where the two species coexisted. Mature trees from Mediterranean (Spain) and sub-Mediterranean (Slovenia) sites, and from sub-Mediterranean (Slovenia) and temperate (Slovenia) sites were selected. Repeated sampling was performed throughout the year and samples were prepared for examination with light and transmission electron microscopes. We hypothesized that cambial rhythm in trees growing at the sub-Mediterranean site where the two species co-exist will be similar as at typical sites for their growth. Cambium in at the Mediterranean site was active throughout the year and was never truly dormant, whereas at the sub-Mediterranean site it appeared to be dormant during the winter months. In contrast, cambium in was clearly dormant at both sub-Mediterranean and temperate sites, although the dormant period seemed to be significantly longer at the temperate site. Thus, the hypothesis was only partly confirmed. Different cambial and cell differentiation rhythms of the two species at the site where both species co-exist and typical sites for their growth indicate their high but different adaptation strategies in terms of adjustment of radial growth to environmental heterogeneity, crucial for long-term tree performance and survival.
    Subject(s): Physiological aspects ; Temperate climates ; Cambium ; Research ; Pine ; Growth ; Aleppo pine ; xylem ; Plant Science ; Scots pine ; cambium ; transmission electron microscopy ; light microscopy ; Mediterranean environment ; temperate environment
    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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  • 8
    Language: English
    In: IAWA journal, 2016-07, Vol.37 (2), p.349-364
    Description: Annual periodicity of cambium production of xylem and phloem cells has rarely been compared in trees from different environments. We compared the structure of cambium and the youngest xylem and phloem increments in four tree species, Fagus sylvatica, Picea abies, Pinus sylvestris and Pinus halepensis, from nine temperate and Mediterranean sites in Slovenia and Spain. In Picea abies, Pinus sylvestris and Fagus sylvatica from temperate locations in Slovenia, xylem and phloem growth ring boundaries could be identified. In Fagus sylvatica growing at two elevations on Moncayo mountain, Spain, phloem increment consisted of only early phloem. In Pinus sylvestris from the same two sites, growth ring boundaries were not as clear as in temperate Slovenian sites. In some cases we could identify phloem growth ring boundaries but in others it was very doubtful, which could be explained by collapse of the outermost early phloem sieve cells. In Pinus halepensis from all sites, we could only distinguish between collapsed and non-collapsed phloem, while phloem rings could not be identified. Widths of the youngest phloem and xylem annual increments could only be compared when phloem increments could be clearly defined, as with Picea abies, Fagus sylvatica and Pinus sylvestris from temperate sites. The visibility of the growth ring boundary in phloem was not related to the width of annual radial growth. The correlation between xylem and phloem ring widths was high, but moderate between the number of dormant cambial cells and xylem ring and phloem ring widths. Based on the structure of the youngest phloem increments, we concluded that there is no typical annual periodicity in cambial production of phloem cells in trees from certain Mediterranean sites. This may be due to continuous yearlong cell production and the absence of true cambium dormancy, at least on the phloem side, under mild winter conditions.
    ISSN: 0928-1541
    E-ISSN: 2294-1932
    E-ISSN: 0928-1541
    Source: Academic Search Ultimate
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  • 9
    Language: English
    In: Forests, 2018-08-30, Vol.9 (9), p.524
    Description: Drought is one of the key natural hazards impacting net primary production and tree growth in forest ecosystems. Nonetheless, tree species show different responses to drought events, which make it difficult to adopt fixed tools for monitoring drought impacts under contrasting environmental and climatic conditions. In this study, we assess the response of forest growth and a satellite proxy of the net primary production (NPP) to drought in peninsular Spain and the Balearic Islands, a region characterized by complex climatological, topographical, and environmental characteristics. Herein, we employed three different indicators based on in situ measurements and satellite image-derived vegetation information (i.e., tree-ring width, maximum annual greenness, and an indicator of NPP). We used seven different climate drought indices to assess drought impacts on the tree variables analyzed. The selected drought indices include four versions of the Palmer Drought Severity Index (PDSI, Palmer Hydrological Drought Index (PHDI), Z-index, and Palmer Modified Drought Index (PMDI)) and three multi-scalar indices (Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Precipitation Drought Index (SPDI)). Our results suggest that—irrespective of drought index and tree species—tree-ring width shows a stronger response to interannual variability of drought, compared to the greenness and the NPP. In comparison to other drought indices (e.g., PDSI), and our results demonstrate that multi-scalar drought indices (e.g., SPI, SPEI) are more advantageous in monitoring drought impacts on tree-ring growth, maximum greenness, and NPP. This finding suggests that multi-scalar indices are more appropriate for monitoring and modelling forest drought in peninsular Spain and the Balearic Islands.
    Subject(s): forest productivity ; normalized difference vegetation index ; tree-rings ; drought indices ; Spain
    ISSN: 1999-4907
    E-ISSN: 1999-4907
    Source: Directory of Open Access Journals
    Source: ProQuest Central
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  • 10
    Language: English
    In: European journal of forest research, 2019, Vol.138 (2), p.299-312
    Description: Forests exhibit strategies to cope with climate change; however, the rate of the changes on forests can be slower than the actual changes in environmental conditions. Forest management policies, such as assisted migration, may help forests to adapt their species distribution to changing climate conditions. Nonetheless, it certainly requires a better knowledge of climate influences on trees to ensure the success of specific management actions. In this study, we apply dendroclimatological methods to investigate the growth response of the main forest species present in Moncayo Natural Park to climate to assess their current relationship and to model these responses over the potential distribution of each species across the study area. Our results revealed large differences in the response of beech, pine and Pyrenean oak to prevailing climate factors and indicated species-specific patterns of climate sensitivity. The general importance of summer conditions for tree growth was confirmed. In addition, we found directional trends in correlation with specific climate factors along spatial gradients; these results are consistent with the autoecology of the studied species. Based on these findings, we present a new model approach that can serve as a key tool for forest managers to design forest communities that are more stable during climatic change.
    Subject(s): GAMs ; Forest management ; Climate ; Tree growth ; Dendrochronology ; Life Sciences ; Forestry ; Plant Sciences ; Plant Ecology
    ISSN: 1612-4669
    E-ISSN: 1612-4677
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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