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  • 1
    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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  • 2
    Language: English
    In: Annals of botany, 2013-12-01, Vol.112 (9), p.1911-1920
    Description: • Background and Aims Ongoing global warming has been implicated in shifting phenological patterns such as the timing and duration of the growing season across a wide variety of ecosystems. Linear models are routiriely used to extrapolate these observed shifts in phenology into the future and to estimate changes in associated ecosystem properties such as net primary productivity. Yet, in nature, linear relationships may be special cases. Biological processes frequently follow more complex, non-linear patterns according to limiting factors that generate shifts and discontinuities, or contain thresholds beyond which responses change abruptly. This study investigates to what extent cambium phenology is associated with xylem growth and differentiation across conifer species of the northern hemisphere. • Methods Xylem cell production is compared with the periods of cambial activity and cell differentiation assessed on a weekly time scale on histological sections of cambium and wood tissue collected from the stems of nine species in Canada and Europe over 1-9 years per site from 1998 to 2011. • Key Results The dynamics of xylogenesis were surprisingly homogeneous among conifer species, although dispersions from the average were obviously observed. Within the range analysed, the relationships between the phenological timings were linear, with several slopes showing values close to or not statistically different from 1. The relationships between the phenological timings and cell production were distinctly non-linear, and involved an exponential pattern • Conclusions The trees adjust their phenological timings according to linear patterns. Thus, shifts of one phenological phase are associated with synchronous and comparable shifts of the successive phases. However, small increases in the duration of xylogenesis could correspond to a substantial increase in cell production. The findings suggest that the length of the growing season and the resulting amount of growth could respond differently to changes in environmental conditions.
    Subject(s): Climate change ; Cell growth ; Xylem ; Tracheids ; Phenology ; Cell walls ; Conifers ; Cambium ; Cellular differentiation ; Species ; Cambium - growth & development ; Canada ; Xylem - cytology ; Climate Change ; Coniferophyta - growth & development ; Europe ; Xylem - growth & development ; Cell Differentiation ; Index Medicus ; Life Sciences ; xylogenesis ; cell production ; cell differentiation ; secondary wall formation ; conifers ; meristem ; productivity ; phenology ; growth ; Original ; climate change
    ISSN: 0305-7364
    E-ISSN: 1095-8290
    Source: Academic Search Ultimate
    Source: PubMed Central
    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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  • 3
    Language: English
    In: International journal of climatology, 2015-08, Vol.35 (10), p.3160-3171
    Description: ABSTRACT Tree rings and documentary evidence are the most important palaeoclimatic archives with annual resolution that continuously span several centuries. Despite this benefit, local to regional‐scale temperature reconstructions and their spatial signatures tend to be irregularly distributed, and the appropriate extent of low‐frequency variability captured in these proxy records remains uncertain. Here, the first summer temperature reconstruction from the Czech Sudetes Mountains that extends to 1700 AD was introduced. An ensemble reconstruction approach using 251 new high‐elevation spruce ring width samples suggests particularly cold June–July temperatures at the beginning of the 18th century, in the 1740s and around 1820. Markedly warm conditions occurred in the 1790s and during the most recent decades. The reconstructed decadal summer temperature amplitude from ‘Little Ice Age Cooling’ to ‘Recent Anthropogenic Warming’ ranges from −3.5 °C between 1700 and 1710 to 1.3 °C in 1999–2009, with respect to the 1961–1990 mean climatology. Comparison of our new reconstruction with existing tree‐ring chronologies from the Alps reveals a significant level of coherency that is much higher than the agreement with geographically closer documentary evidence from Central Europe. Our study confirms the importance of independent regional climate reconstructions, which capture the full range of past variability and also fill spatial gaps in large‐scale networks.
    Subject(s): proxy archives ; Sudetes ; documentary evidence ; warming ; Norway spruce ; Little Ice Age ; dendroclimatology ; tree rings ; climate reconstruction ; Dendrochronology
    ISSN: 0899-8418
    E-ISSN: 1097-0088
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: Tree physiology, 2013-09, Vol.33 (9), p.913-923
    Description: The presence of soluble carbohydrates in the cambial zone, either from sugars recently produced during photosynthesis or from starch remobilized from storage organs, is necessary for radial tree growth. However, considerable uncertainties on carbohydrate dynamics and the consequences on tree productivity exist. This study aims to better understand the variation in different carbon pools at intra-annual resolution by quantifying how cambial zone sugar and starch concentrations fluctuate over the season and in relation to cambial phenology. A comparison between two physiologically different species growing at the same site, i.e., the evergreen Picea abies Karst. and the deciduous Larix decidua Mill., and between L. decidua from two contrasting elevations, is presented to identify mechanisms of growth limitation. Results indicate that the annual cycle of sugar concentration within the cambial zone is coupled to the process of wood formation. The highest sugar concentration is observed when the number of cells in secondary wall formation and lignification stages is at a maximum, subsequent to most radial growth. Starch disappears in winter, while other freeze-resistant non-structural carbohydrates (NSCs) increase. Slight differences in NSC concentration between species are consistent with the differing climate sensitivity of the evergreen and deciduous species investigated. The general absence of differences between elevations suggests that the cambial activity of trees growing at the treeline was not limited by the availability of carbohydrates at the cambial zone but instead by environmental controls on the growing season duration.
    Subject(s): Trees - metabolism ; Xylem - physiology ; Coniferophyta - growth & development ; Cell Count ; Larix - metabolism ; Trees - growth & development ; Cambium - growth & development ; Cambium - metabolism ; Analysis of Variance ; Carbohydrates - chemistry ; Time Factors ; Picea - growth & development ; Coniferophyta - metabolism ; Larix - growth & development ; Seasons ; Cambium - cytology ; Picea - metabolism ; Index Medicus
    ISSN: 0829-318X
    E-ISSN: 1758-4469
    Source: Academic Search Ultimate
    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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  • 5
    Language: English
    In: International journal of climatology, 2015-08, Vol.35 (10), p.3160-3171
    ISSN: 0899-8418
    E-ISSN: 1097-0088
    Source: Alma/SFX Local Collection
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  • 6
    Language: English
    In: Journal of allergy and clinical immunology, 2013, Vol.131 (5), p.1322-1328
    Description: Background Exacerbations of asthma are thought to be caused by airflow obstruction resulting from airway inflammation, bronchospasm, and mucus plugging. Histologic evidence suggests the small airways, including acinar air spaces, are involved; however, this has not been corroborated in vivo by measurements of peripheral small-airway function. Objective We sought to determine whether asthma severity is linked to small-airway function, particularly in patients with acute severe asthma. Methods Eighteen subjects admitted for an asthma exacerbation underwent lung function testing, including measures of acinar ventilation heterogeneity (Sacin ) and conductive ventilation heterogeneity (Scond ) using the multiple-breath nitrogen washout. Treatment requirement was defined according to Global Initiative for Asthma scores. Data were compared with those obtained in 19 patients with stable asthma. Results For the asthma exacerbation group, the median FEV1 was 59% of predicted value (95% CI, 45% to 75% of predicted value), the median Scond value was 185% of predicted value (95% CI, 119% to 245% of predicted value), and the median Sacin value was 225% of predicted value (95% CI, 143% to 392% of predicted value). FEV1 (percent predicted) was correlated with Sacin (percent predicted) values (Spearman rho = −0.67, P  = .006) but not with Scond (percent predicted) values ( P  〉 .1). The Global Initiative for Asthma score was significantly related to Sacin (percent predicted) (Spearman rho = 0.59, P  = .016) but not to Scond (percent predicted) values ( P  〉 .1). The unstable group was characterized by considerably lower forced vital capacity ( P  〈 .001) and higher Scond ( P  = .001) values than the unstable group. In a subgroup of 11 unstable patients who could be reviewed after 4 weeks, FEV1 , forced vital capacity, Sacin , and Scond values showed marked improvements. Conclusion Our findings suggest that unstable asthma is characterized by a combined abnormality in the acinar and conductive lung zones, both of which are partly reversible. Functional abnormality in the acinar lung zone in particular showed a direct correlation with airflow obstruction and treatment requirement in patients with acute severe asthma.
    Subject(s): Allergy and Immunology ; peripheral gas mixing ; acinar airways ; Severe asthma ; Fundamental and applied biological sciences. Psychology ; Fundamental immunology ; Immunopathology ; Biological and medical sciences ; Medical sciences ; Sarcoidosis. Granulomatous diseases of unproved etiology. Connective tissue diseases. Elastic tissue diseases. Vasculitis ; Acute Disease ; Asthma - physiopathology ; Humans ; Middle Aged ; Male ; Lung - physiopathology ; Forced Expiratory Volume ; Vital Capacity ; Asthma - immunology ; Adult ; Female ; Respiratory Function Tests ; Lung - immunology ; Medical colleges ; Respiratory agents ; Care and treatment ; Asthma ; Index Medicus ; Abridged Index Medicus
    ISSN: 0091-6749
    E-ISSN: 1097-6825
    Source: Backfile Package - All of Back Files EBS [ALLOFBCKF]
    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: Annals of botany, 2013-12, Vol.112 (9), p.1911
    Description: Ongoing global warming has been implicated in shifting phenological patterns such as the timing and duration of the growing season across a wide variety of ecosystems. Linear models are routinely used to extrapolate these observed shifts in phenology into the future and to estimate changes in associated ecosystem properties such as net primary productivity. Yet, in nature, linear relationships may be special cases. Biological processes frequently follow more complex, non-linear patterns according to limiting factors that generate shifts and discontinuities, or contain thresholds beyond which responses change abruptly. This study investigates to what extent cambium phenology is associated with xylem growth and differentiation across conifer species of the northern hemisphere. Xylem cell production is compared with the periods of cambial activity and cell differentiation assessed on a weekly time scale on histological sections of cambium and wood tissue collected from the stems of nine species in Canada and Europe over 1-9 years per site from 1998 to 2011. The dynamics of xylogenesis were surprisingly homogeneous among conifer species, although dispersions from the average were obviously observed. Within the range analysed, the relationships between the phenological timings were linear, with several slopes showing values close to or not statistically different from 1. The relationships between the phenological timings and cell production were distinctly non-linear, and involved an exponential pattern. The trees adjust their phenological timings according to linear patterns. Thus, shifts of one phenological phase are associated with synchronous and comparable shifts of the successive phases. However, small increases in the duration of xylogenesis could correspond to a substantial increase in cell production. The findings suggest that the length of the growing season and the resulting amount of growth could respond differently to changes in environmental conditions.
    Subject(s): Cambium - growth & development ; Canada ; Xylem - cytology ; Climate Change ; Coniferophyta - growth & development ; Europe ; Xylem - growth & development ; Cell Differentiation
    E-ISSN: 1095-8290
    Source: Academic Search Ultimate
    Source: PubMed Central
    Source: Alma/SFX Local Collection
    Source: Oxford Journals 2016 Current and Archive A-Z Collection
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  • 8
    Dissertation
    Dissertation
    2009
    ISBN: 0494520167  ISBN: 9780494520161 
    Language: English
    Description: The growth response of white spruce in the Mackenzie Delta, NT to climatic, non-climatic and weather variables in 2006 and 2007 was investigated. Analysis of increment cores from 42 trees at the study site identified three different sub-populations of white spruce. Positive responders had significant, positive response to growing season June temperatures, while negative responders had significant, negative relations to previous June/July temperatures. Active layer depth was significantly different between positive responders and negative responders. Because of this difference, it is hypothesized that an increased availability of soil moisture to the shallow root systems late in the growing season reduced moisture stress in the positive responder sub-population. Along with high-resolution measurements of tree growth that revealed a response of a negative responder to precipitation, these factors suggest that temperature-induced moisture stress may influence individual growth response to climate.
    Subject(s): Environmental science ; Forestry ; Plant sciences
    ISBN: 0494520167
    ISBN: 9780494520161
    Source: ProQuest Dissertations & Theses Global
    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: Journal of Applied Physiology, 2010-01-01, Vol.108 (1), p.206-211
    Description: In obese people, the presence of adipose tissue around the rib cage and abdomen and in the visceral cavity loads the chest wall and reduces functional residual capacity (FRC). The reduction in FRC and in expiratory reserve volume is detectable, even at a modest increase in weight. However, obesity has little direct effect on airway caliber. Spirometric variables decrease in proportion to lung volumes, but are rarely below the normal range, even in the extremely obese, while reductions in expiratory flows and increases in airway resistance are largely normalized by adjusting for lung volumes. Nevertheless, the reduction in FRC has consequences for other aspects of lung function. A low FRC increases the risk of both expiratory flow limitation and airway closure. Marked reductions in expiratory reserve volume may lead to abnormalities in ventilation distribution, with closure of airways in the dependent zones of the lung and ventilation perfusion inequalities. Greater airway closure during tidal breathing is associated with lower arterial oxygen saturation in some subjects, even though lung CO-diffusing capacity is normal or increased in the obese. Bronchoconstriction has the potential to enhance the effects of obesity on airway closure and thus on ventilation distribution. Thus obesity has effects on lung function that can reduce respiratory well-being, even in the absence of specific respiratory disease, and may also exaggerate the effects of existing airway disease.
    Subject(s): Animals ; Models, Biological ; Obesity - complications ; Pulmonary Ventilation ; Humans ; Obesity - physiopathology ; Lung Diseases - physiopathology ; Functional Residual Capacity ; Respiratory Mechanics ; Lung Diseases - etiology ; Index Medicus
    ISSN: 8750-7587
    E-ISSN: 1522-1601
    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: Journal of personality and social psychology, 2015-04, Vol.108 (4), p.637-647
    Description: Laboratory research shows that when people believe that willpower is an abundant (rather than highly limited) resource they exhibit better self-control after demanding tasks. However, some have questioned whether this "nonlimited" theory leads to squandering of resources and worse outcomes in everyday life when demands on self-regulation are high. To examine this, we conducted a longitudinal study, assessing students' theories about willpower and tracking their self-regulation and academic performance. As hypothesized, a nonlimited theory predicted better self-regulation (better time management and less procrastination, unhealthy eating, and impulsive spending) for students who faced high self-regulatory demands. Moreover, among students taking a heavy course load, those with a nonlimited theory earned higher grades, which was mediated by less procrastination. These findings contradict the idea that a limited theory helps people allocate their resources more effectively; instead, it is people with the nonlimited theory who self-regulate well in the face of high demands.
    Subject(s): Young Adult ; Attitude ; Humans ; Adult ; Female ; Male ; Achievement ; Personality - physiology ; Longitudinal Studies ; Analysis ; Self-control ; Index Medicus
    ISSN: 0022-3514
    E-ISSN: 1939-1315
    Source: APA PsycARTICLES
    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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