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  • 1
    Language: English
    In: Global change biology, 2019-01, Vol.25 (1), p.351-360
    Description: Frost events during the active growth period of plants can cause extensive frost damage with tremendous economic losses and dramatic ecological consequences. A common assumption is that climate warming may bring along a reduction in the frequency and severity of frost damage to vegetation. On the other hand, it has been argued that rising temperature in late winter and early spring might trigger the so called “false spring”, that is, early onset of growth that is followed by cold spells, resulting in increased frost damage. By combining daily gridded climate data and 1,489 k in situ phenological observations of 27 tree species from 5,565 phenological observation sites in Europe, we show here that temporal changes in the risk of spring frost damage with recent warming vary largely depending on the species and geographical locations. Species whose phenology was especially sensitive to climate warming tended to have increased risk of frost damage. Geographically, compared with continental areas, maritime and coastal areas in Europe were more exposed to increasing occurrence of frost and these late spring frosts were getting more severe in the maritime and coastal areas. Our results suggest that even though temperatures will be elevated in the future, some phenologically responsive species and many populations of a given species will paradoxically experience more frost damage in the future warming climate. More attention should be paid to the increased frost damage in responsive species and populations in maritime areas when developing strategies to mitigate the potential negative impacts of climate change on ecosystems in the near future. This study examined the well‐known “increased frost damage” hypothesis by Cannell (1985), based on long‐term phenological records and climate data. Temporal changes in the risk of spring frost damage with recent warming vary largely depending on the species and geographical locations. Species whose phenology was especially sensitive to climate warming tended to have increased risk of frost damage. Geographically, compared with continental areas, maritime and coastal areas in Europe were more exposed to increasing occurrence of frost and these late spring frosts were getting more severe in the maritime and coastal areas.
    Subject(s): Biodiversity & Conservation ; climate change ; Ecology ; Ecosystems ; Environmental Sciences ; Environmental Sciences & Ecology ; frost damage ; Global temperature changes ; Life Sciences & Biomedicine ; phenology ; Science & Technology ; spring frost ; temperate tree
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    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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  • 2
    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): Analysis ; boreal forest ; Cambium ; Cambium - physiology ; Carbon cycle (Biogeochemistry) ; Cell Count ; Cell growth ; Climate models ; ecosystem ; Ecosystem models ; Forest ecology ; Forest growth ; Full papers ; Growth ; Mathematical growth ; mixed‐effects model ; Modeling ; Models, Biological ; Organ Specificity ; Phenology ; Photosynthesis ; Physiological aspects ; Plant growth ; primary growth ; Quebec ; secondary growth ; Time Factors ; tree growth ; Trees - growth & development ; Xylem ; Xylem - cytology ; Xylem - growth & development ; xylem formation
    ISSN: 0028-646X
    E-ISSN: 1469-8137
    Source: JSTOR Life Sciences
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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  • 3
    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): Cambium - metabolism ; Carbohydrate metabolism ; Carbohydrates - analysis ; Carbon - metabolism ; Cell Differentiation ; ECOPHYSIOLOGY AND SUSTAINABILITY ; Models, Biological ; Observations ; Physiological aspects ; Picea - cytology ; Picea - growth & development ; Picea - metabolism ; Plant-water relationships ; Solubility ; Spruce ; Temperature ; Trees - growth & development ; Water - metabolism ; Wood - cytology ; Wood - growth & development ; Xylem - metabolism
    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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  • 4
    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): Analysis ; Biomes ; cambium ; Cell differentiation ; cell production ; climate change ; Cold Temperature ; Coniferophyta ; conifers ; Ecosystem ; Ecosystems ; Environmental aspects ; Global temperature changes ; growth ; Life Sciences ; meristem ; Plant Development ; Seasons ; secondary wall formation ; Trees ; Vegetal Biology ; Xylem
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Molecular cancer, 2017-10-17, Vol.16 (1), p.161-161
    Description: The conversion from estrogen-dependent to estrogen-independent state of ER+ breast cancer cells is the key step to promote resistance to endocrine therapies. Although the crucial role of MAPK/ERK signaling pathway in estrogen-independent breast cancer cell growth is well established, the underlying mechanism is not fully understood. In this study, we profiled lncRNA expression against a focused group of lncRNAs selected from lncRNA database. CRISPR/Cas9 was employed to knockout (KO) linc-RoR in MCF-7 cells, while rescue experiments were carried out to re-express linc-RoR in KO cells. Colony formation and MTT assays were used to examine the role of linc-RoR in estrogen-independent growth and tamoxifen resistance. Western blot and qRT-PCR were used to determine the change of protein and lncRNA levels, respectively. The expression of DUSP7 in clinical specimens was downloaded from Oncomine ( www.oncomine.org ) and the dataset from Kaplan-Meier Plotter ( http://kmplot.com ) was used to analyze the clinical outcomes in relation to DUSP7. We identified that linc-RoR functions as an onco-lncRNA to promote estrogen-independent growth of ER+ breast cancer. Under estrogen deprivation, linc-RoR causes the upregulation of phosphorylated MAPK/ERK pathway which in turn activates ER signaling. Knockout of linc-RoR abrogates estrogen deprivation-induced ERK activation as well as ER phosphorylation, whereas re-expression of linc-RoR restores all above phenotypes. Moreover, we show that the ERK-specific phosphatase Dual Specificity Phosphatase 7 (DUSP7), also known as MKP-X, is involved in linc-RoR KO-induced repression of MAPK/ERK signaling. Interestingly, linc-RoR KO increases the protein stability of DUSP7, resulting in repression of ERK phosphorylation. Clinical data analysis reveal that DUSP7 expression is lower in ER+ breast cancer samples than that in ER- breast cancer. Moreover, downregulation of DUSP7 expression is associated with poor patient survival. Taken together, these results suggest that linc-RoR promotes estrogen-independent growth and activation of MAPK/ERK pathway of breast cancer cells by regulating the ERK-specific phosphatase DUSP7. Thus, this study might help not only in establishing a role for linc-RoR in estrogen-independent and tamoxifen resistance of ER+ breast cancer, but also suggesting a link between linc-RoR and MAPK/ERK pathway.
    Subject(s): Breast cancer ; DUSP7 ; ERK ; Estrogen-independent growth ; Linc-RoR ; Research
    ISSN: 1476-4598
    E-ISSN: 1476-4598
    Source: BioMedCentral Open Access
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: DOAJ Directory of Open Access Journals - Not for CDI Discovery
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  • 6
    Language: English
    In: Global change biology, 2018-02, Vol.24 (2), p.655-667
    Description: Insects, diseases, fire and drought and other disturbances associated with global climate change contribute to forest decline and mortality in many parts of the world. Forest decline and mortality related to drought or insect outbreaks have been observed in North American aspen forests. However, little research has been done to partition and estimate their relative contributions to growth declines. In this study, we combined tree‐ring width and basal area increment series from 40 trembling aspen (Populus tremuloides Michx.) sites along a latitudinal gradient (from 52° to 58°N) in western Canada and attempted to investigate the effect of drought and insect outbreaks on growth decline, and simultaneously partition and quantify their relative contributions. Results indicated that the influence of drought on forest decline was stronger than insect outbreaks, although both had significant effects. Furthermore, the influence of drought and insect outbreaks showed spatiotemporal variability. In addition, our data suggest that insect outbreaks could be triggered by warmer early spring temperature instead of drought, implicating that potentially increased insect outbreaks are expected with continued warming springs, which may further exacerbate growth decline and death in North America aspen mixed forests. The influence of drought on forest decline was stronger compared to insect outbreaks. In addition, insect outbreaks could be triggered by warmer early spring temperature or climate oscillation instead of drought, implicating that potentially increased insect outbreaks are expected with continued warming springs, which may further exacerbate growth decline and death in North America aspen mixed forests.
    Subject(s): Animals ; boreal forest ; Canada ; Climate Change ; Climatic changes ; drought ; Droughts ; forest decline ; Forests ; Health aspects ; insect outbreaks ; Insecta - physiology ; Populus - growth & development ; Statistics ; Taiga ; Temperature ; Trees ; trembling aspen
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 7
    Language: English
    In: Global change biology, 2017-07, Vol.23 (7), p.2887-2902
    Description: Adequate and advance knowledge of the response of forest ecosystems to temperature‐induced drought is critical for a comprehensive understanding of the impacts of global climate change on forest ecosystem structure and function. Recent massive decline in aspen‐dominated forests and an increased aspen mortality in boreal forests have been associated with global warming, but it is still uncertain whether the decline and mortality are driven by drought. We used a series of ring‐width chronologies from 40 trembling aspen (Populus tremuloides Michx.) sites along a latitudinal gradient (from 52° to 58°N) in western Canada, in an attempt to clarify the impacts of drought on aspen growth by using Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI). Results indicated that prolonged and large‐scale droughts had a strong negative impact on trembling aspen growth. Furthermore, the spatiotemporal variability of drought indices is useful for explaining the spatial heterogeneity in the radial growth of trembling aspen. Due to ongoing global warming and rising temperatures, it is likely that severer droughts with a higher frequency will occur in western Canada. As trembling aspen is sensitive to drought, we suggest that drought indices could be applied to monitor the potential effects of increased drought stress on aspen trees growth, achieve classification of eco‐regions and develop effective mitigation strategies to maintain western Canadian boreal forests. Droughts are closely related to the reduced growth of trembling aspen in western Canadian boreal forests. Drought indices could be applied to monitor the potential effects of increased drought stress on aspen trees growth, achieving classification of eco‐regions and developing effective mitigation strategies to maintain western Canadian boreal forests.
    Subject(s): boreal forest ; Canada ; Climate Change ; drought ; Droughts ; Ecosystem components ; Forest ecology ; Forests ; Global warming ; Growth ; Mortality ; Populus - growth & development ; Precipitation (Meteorology) ; radial growth ; spatial variation ; Trees ; trembling aspen
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 8
    Language: English
    In: Global change biology, 2018-09, Vol.24 (9), p.3969-3975
    Description: Under current global warming, high‐elevation regions are expected to experience faster warming than low‐elevation regions. However, due to the lack of studies based on long‐term large‐scale data, the relationship between tree spring phenology and the elevation‐dependent warming is unclear. Using 652k records of leaf unfolding of five temperate tree species monitored during 1951–2013 in situ in Europe, we discovered a nonlinear trend in the altitudinal sensitivity (SA, shifted days per 100 m in altitude) in spring phenology. A delayed leaf unfolding (2.7 ± 0.6 days per decade) was observed at high elevations possibly due to decreased spring forcing between 1951 and 1980. The delayed leaf unfolding at high‐elevation regions was companied by a simultaneous advancing of leaf unfolding at low elevations. These divergent trends contributed to a significant increase in the SA (0.36 ± 0.07 days 100/m per decade) during 1951–1980. Since 1980, the SA started to decline with a rate of −0.32 ± 0.07 days 100/m per decade, possibly due to reduced chilling at low elevations and improved efficiency of spring forcing in advancing the leaf unfolding at high elevations, the latter being caused by increased chilling. Our results suggest that due to both different temperature changes at the different altitudes, and the different tree responses to these changes, the tree phenology has shifted at different rates leading to a more uniform phenology at different altitudes during recent decades. A delayed leaf unfolding was observed at high elevations possibly due to decreased spring forcing between 1951 and 1980. The delayed leaf unfolding at high‐elevation regions was companied by a simultaneous advanced leaf unfolding at low elevations. Our results suggest that due to both different temperature changes at the different altitudes, and the different tree responses to these changes, the tree phenology has shifted at different rates leading to a more uniform phenology at different altitudes during recent decades
    Subject(s): Air pollution ; Altitude ; Biological monitoring ; climate change ; elevation‐dependent warming ; Environmental aspects ; Europe ; Global Warming ; leaf unfolding ; phenology ; Plant Leaves - physiology ; Seasons ; Temperature ; Trees - growth & development ; Trees - physiology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: Global change biology, 2019-03, Vol.25 (3), p.997-1004
    Description: Contrary to the generally advanced spring leaf unfolding under global warming, the effects of the climate warming on autumn leaf senescence are highly variable with advanced, delayed, and unchanged patterns being all reported. Using one million records of leaf phenology from four dominant temperate species in Europe, we investigated the temperature sensitivities of spring leaf unfolding and autumn leaf senescence (ST, advanced or delayed days per degree Celsius). The ST of spring phenology in all of the four examined species showed an increase and decrease during 1951–1980 and 1981–2013, respectively. The decrease in the ST during 1981–2013 appears to be caused by reduced accumulation of chilling units. As with spring phenology, the ST of leaf senescence of early successional and exotic species started to decline since 1980. In contrast, for late successional species, the ST of autumn senescence showed an increase for the entire study period from 1951 to 2013. Moreover, the impacts of rising temperature associated with global warming on spring leaf unfolding were stronger than those on autumn leaf senescence. The timing of leaf senescence was positively correlated with the timing of leaf unfolding during 1951–1980. However, as climate warming continued, the differences in the responses between spring and autumn phenology gradually increased, so that the correlation was no more significant during 1981–2013. Our results further suggest that since 2000, due to the decreased temperature sensitivity of leaf unfolding the length of the growing season has not increased any more. These finding needs to be addressed in vegetation models used for assessing the effects of climate change. Here, we found both impacts of climate warming on both spring and autumn phenology declined in recent decades. In addition, the impacts of rising temperature associated with global warming on spring leaf unfolding were stronger than those on autumn leaf senescence. The timing of leaf senescence was positively correlated with the timing of leaf unfolding during 1951–1980. However, as climate warming continued, the differences in the responses between spring and autumn phenology gradually increased, the correlation was no more significant during 1981–2013. These findings need to be addressed in vegetation models used for assessing the effects of climate change.
    Subject(s): Air pollution ; Analysis ; Biodiversity & Conservation ; chilling units ; climate warming ; early and late successional species ; Ecology ; Environmental aspects ; Environmental Sciences ; Environmental Sciences & Ecology ; Europe ; exotic species ; Global Warming ; Life Sciences & Biomedicine ; phenology ; photoperiod ; Plant Leaves - physiology ; Science & Technology ; Seasons ; Species Specificity ; Temperature ; Time Factors ; Trees - physiology
    ISSN: 1354-1013
    E-ISSN: 1365-2486
    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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  • 10
    Language: English
    In: The Journal of ecology, 2021-03, Vol.109 (3), p.1319-1330
    Description: Leaf‐out and flowering are two key phenological events of plants, denoting the respective onsets of visible vegetative growth and reproduction during the year. For each species, the schedule of vegetative growth and reproduction is crucial to the maximization of its fitness. Warming‐induced advances of leaf‐out and flowering have been reported frequently; however, it is unclear whether the responses of the two events are equal for any given species. Using long‐term phenological records in Europe, we examined simultaneously the responses of both leaf‐out and flowering of four common temperate tree species to climate warming and further examined the effects of winter chilling, spring forcing and photoperiod on the responses of the two events. We found that regardless whether flowering or leaf‐out occurred first, the first event advanced more than the second during 1950–2013, resulting in a prolonged time interval between the two events. The temporal changes were also supported by a similar geographical trend that the time interval between the two events increased from cold to warm sites. Due to the warming‐induced reduction in chilling, the spring forcing accumulated until the second event was increased more than the forcing accumulated until the first event, and that reduced the temperature sensitivity of the second event. In addition to the effect of chilling, the shorter photoperiod, associated with the advanced spring phenology, was also likely to substantially increase the spring forcing accumulated until the second event, which thus slowed down its advance, compared to the advance of the first event. The relative contributions of chilling and photoperiod to the increased forcing varied between species and events, with chilling mostly outweighing photoperiod. Synthesis. This study provides the large‐scale empirical evidence of prolonged time interval between leaf‐out and flowering with climate warming. The unequal advances of the two events may alter the partition of resources between vegetative growth and reproduction and cause different changes of spring frost damage to vegetative and reproductive tissues, which may alter species fitness and further affect ecosystem structure and function. This study provides the large‐scale empirical evidence of prolonged time interval between leaf‐out and flowering with climate warming. The unequal advances of the two events may alter the partition of resources between vegetative growth and reproduction and cause different changes of spring frost damage to vegetative and reproductive tissues, which may alter species fitness and further affect ecosystem structure and function.
    Subject(s): chilling ; climate warming ; flowering ; forcing ; leaf‐out ; photoperiod ; plant–climate interactions ; spring phenology
    ISSN: 0022-0477
    E-ISSN: 1365-2745
    Source: Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals
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