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  • 1
    Language: English
    In: Forest Ecology and Management, Dec 15, 2013, Vol.310, p.110(10)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.foreco.2013.08.006 Byline: Michael Goisser, Ulrich Zang, Egbert Matzner, Werner Borken, Karl-Heinz Haberle, Rainer Matyssek Abstract: acents Response of juvenile European beech upon transplant to heterogeneous light and water availability. acents Plant response was examined along the gradients of light and water availability. acents High light acclimation exacerbated productivity decline under drought. acents Progressive acclimation to shade and drought mitigated productivity decline within the study period. Article History: Received 18 April 2013; Revised 4 August 2013; Accepted 5 August 2013
    Keywords: Water ; Industrial Productivity
    ISSN: 0378-1127
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Forest Ecology and Management, 15 December 2013, Vol.310, pp.110-119
    Description: Climate models predict increasing frequency and intensity of summer drought events for Central Europe. In a field experiment, we investigated the response of young beech ( L.) to extreme and repeated summer drought and the modulation of drought response patterns along the natural gradient of light availability at the study site. In autumn 2008, two-year-old, nursery derived beech – as used for forest conversion practices – was planted under a Norway spruce stand primarily opened through winter storm. Precipitation was manipulated in the growing seasons of 2009 through 2011, inducing a pronounced gradient of water availability. Individual drought-stress doses (DSD) and light doses (LD) were calculated for each beech sapling during the three growing seasons. Plant growth, CO -assimilation rate and stomatal conductance were reduced with increasing drought stress, but facilitated by increasing light availability. Progressive acclimation to water and light limitation during the three years of the experiment led to a decreased drought and shade sensitivity of diameter growth. Water-use efficiency, root/shoot ratio and rooting depth, were increased with decreasing water availability. Mean fine root diameter and specific fine root length correlated positively with both DSD and LD. Proceeding low-light acclimation was indicated by progressively increasing specific leaf area and reduced leaf dark-respiration. Present results suggest that nursery-induced high-light acclimation of the beech saplings, exacerbated light limitation upon transplant and hence productivity decline under co-occurring water limitation.
    Keywords: European Beech ; Drought ; Light ; Restoration ; Acclimation ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 3
    In: Tree Physiology, 2018, Vol. 39(2), pp.192-200
    Description: Phloem sustains maintenance and growth processes through transport of sugars from source to sink organs. Under low water availability, tree functioning is impaired, i.e., growth/photosynthesis decline and phloem transport may be hindered. In a 3-year throughfall exclusion (TE) experiment on mature European beech ( Fagus sylvatica L.) we conducted 13 CO 2 branch labeling to investigate translocation of recently fixed photoassimilates under experimental drought over 2 years (2015 and 2016). We hypothesized (H1) that mean residence time of photoassimilates in leaves (MRT) increases, whereas (H2) phloem transport velocity ( V phloem ) decreases under drought. Transport of carbohydrates in the phloem was assessed via δ 13 C of CO 2 efflux measured at two branch positions following 13 CO 2 labeling. Pre-dawn water potential (Ψ PD ) and time-integrated soil water deficit (iSWD) were used to quantify drought stress. The MRT increased by 46% from 32.1 ± 5.4 h in control (CO) to 46.9 ± 12.3 h in TE trees, supporting H1, and positively correlated ( P 〈 0.001) with iSWD. Confirming H2, V phloem in 2016 decreased by 47% from 20.7 ± 5.8 cm h –1 in CO to 11.0 ± 2.9 cm h –1 in TE trees and positively correlated with Ψ PD ( P = 0.001). We suggest that the positive correlation between MRT and iSWD is a result of the accumulation of osmolytes maintaining cell turgor in the leaves under longer drought periods. Furthermore, we propose that the positive correlation between V phloem and Ψ PD is due to a lower water uptake of phloem conduits from surrounding tissues under increasing drought leading to a higher phloem sap viscosity and lower V phloem . The two mechanisms increasing MRT and reducing V phloem respond differently to low water availability and impair trees’ carbon translocation under drought.
    Keywords: Drought Stress Dose ; 〈Kwd〉 〈Italic Toggle="Yes"〉Fagus Sylvatica〈/Italic〉 〈/Kwd〉 ; Mean Residence Time ; Phloem Transport Velocity ; Stable Carbon Isotope (C) Labeling ; Water Potential
    ISSN: 0829318X
    E-ISSN: 1758-4469
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  • 4
    Language: English
    In: Journal of Plant Nutrition and Soil Science, April 2014, Vol.177(2), pp.168-177
    Description: Soil drought influences the C turnover as well as the fine‐root system of tree saplings. Particularly during the period of establishment, the susceptibility to drought stress of saplings is increased because of incompletely developed root systems and reduced access to soil water. Here, we subjected beech saplings ( L.) to different levels of drought stress. Beech saplings were planted in rhizotrons, which were installed in the soil of a Norway spruce forest before bud burst. Soil moisture was manipulated in the following year during May to September. We measured photosynthetic net CO uptake, volume production of fine roots, and rhizosphere respiration during the growing season. Biometric parameters of the fine‐root system, biomass, and nonstructural carbohydrates were analyzed upon harvest in October. Photosynthesis and rhizosphere respiration decreased with increasing drought‐stress dose (cumulated soil water potential), and cumulative rhizosphere respiration was significantly negatively correlated with drought‐stress dose. Fine‐root length and volume production were highest at moderate soil drought, but decreased at severe soil drought. The proportion of fine‐roots diameter 〈 0.2 mm and the root‐to‐shoot ratio increased whereas the live‐to‐dead ratio of fine roots decreased with increasing drought‐stress dose. We conclude that the belowground C allocation as well as the relative water‐uptake efficiency of beech saplings is increased under drought.
    Keywords: Drought Stress ; European Beech ; Fine Roots ; Rhizosphere Respiration ; Rhizotrons
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 5
    In: Tree Physiology, 2014, Vol. 34(1), pp.29-38
    Description: Drought reduces the carbon (C) assimilation of trees and decouples aboveground from belowground carbon fluxes, but little is known about the response of drought-stressed trees to rewetting. This study aims to assess dynamics and patterns of C allocation in beech saplings under dry and rewetted soil conditions. In October 2010, 5-year-old beech saplings from a forest site were transplanted into 20 l pots. In 2011, the saplings were subjected to different levels of soil drought ranging from non-limiting water supply (control) to severe water limitation with soil water potentials of less than −1.5 MPa. As a physiologically relevant measure of drought, the cumulated soil water potential (i.e., drought stress dose (DSD)) was calculated for the growing season. In late August, the saplings were transferred into a climate chamber and pulse-labeled with 13 C-depleted CO 2 (δ 13 C of −47‰). Isotopic signatures in leaf and soil respiration were repeatedly measured. Five days after soil rewetting, a second label was applied using 99 atom% 13 CO 2 . After another 12 days, the fate of assimilated C in each sapling was assessed by calculating the 13 C mass balance. Photosynthesis decreased by 60% in saplings under severe drought. The mean residence time (MRT) of recent assimilates in leaf respiration was more than three times longer than under non-limited conditions and was positively correlated to DSD. Also, the appearance of the label in soil respiration was delayed. Within 5 days after rewetting, photosynthesis, MRT of recent assimilates in leaf respiration and appearance of the label in soil respiration recovered fully. Despite the fast recovery, less label was recovered in the biomass of the previously drought-stressed plants, which also allocated less C to the root compartment (45 vs 64% in the control). We conclude that beech saplings quickly recover from extreme soil drought, although transitional after-effects prevail in C allocation, possibly due to repair-driven respiratory processes.
    Keywords: Carbon Balance ; Carbon Fluxes ; Drought Stress Quantification ; Labeling ; Recovery
    ISSN: 0829-318X
    E-ISSN: 1758-4469
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  • 6
    Language: English
    In: Clinical interventions in aging, 2015, Vol.10, pp.1565-73
    Description: Although sarcopenia represents a challenging burden for health care systems around the world, its prevalence in the elderly population varies widely. The primary aim of the study was to determine the prevalence of sarcopenia in community-dwelling (CD) German women aged 70 years and older; the secondary aim was to assess the effect of osteoarthritis (OA) on sarcopenia prevalence in this cohort. A total of 689 Caucasian females 18-35 years old and 1,325 CD females 70 years+ living in Northern Bavaria, Germany, were assessed during the initial phase of the FORMoSA research project. Anthropometry, total and regional muscle mass, were assessed by segmental multifrequency Bioelectrical Impedance Analysis. Further 10 m walking speed and handgrip strength were evaluated to apply the European Working Group on Sarcopenia in Older People definition of sarcopenia. Covariates were determined by questionnaires and interviews. Applying the algorithm of the European Working Group on Sarcopenia in Older People of two standard deviations below the mean value for appendicular skeletal muscle mass of a reference cohort of the young cohort (5.66 kg/m(2)), low gait speed (≤0.8 m/s), and low grip strength (〈20 kg), the prevalence of sarcopenia in CD German females 70 years and older was 4.5% (70-79 years: 2.8% vs ≥80 years: 9.9%; P〈0.001). Participants with OA at the hip and lower limbs (n=252) exhibited significantly higher rates of sarcopenia (OA: 9.1 vs non-OA: 3.5%). Of importance, anthropometric, demographic, health, and lifestyle parameters (except exercise participation) of our cohorts corresponded with Bavarian or German data for CD women 70 years+. The prevalence of sarcopenia in CD German females 70 years+ is relatively low. However, participants with OA at the hip or lower limbs were at increased risk for sarcopenia.
    Keywords: Germany ; Osteoarthritis ; Prevalence ; Sarcopenia ; Osteoarthritis -- Epidemiology ; Sarcopenia -- Epidemiology
    E-ISSN: 1178-1998
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  • 7
    Language: English
    In: Clinical Nutrition, August 2018, Vol.37(4), pp.1141-1144
    Description: Studies have shown that omega-3 polyunsaturated fatty acids (PUFAs) are associated with brain, cardiovascular and immune function, as well as physical performance and bone health in older adults. So far, few studies have highlighted the associations between PUFA status and performance-based tests of physical function. To study the associations between the omega-3 index (red blood cell (RBC) membrane content of omega-3 PUFAs, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) and physical performance measured with the Short Physical Performance Battery (SPPB) in a sample of community-dwelling older adults. Cross-sectional study using the baseline data of the Multidomain Alzheimer's Disease Trial (MAPT), a randomized, placebo-controlled trial. 1449 participants with available data on PUFAs were included. Omega-3 index and Short Physical Performance Battery (SPPB) scores were measured at enrollment and the omega-3 index expressed as the percentage of total fatty acid content was calculated. We also dichotomized the omega-3 index as low (lowest quartile) vs. high (three upper quartiles). Participants were 75.2 (±4.4) years old, 64.5% were female. Bivariate analyses found that participants who were in the lowest omega-3 index quartile (Q1) had a SPPB score significantly lower than participants in the three other quartiles (Q2–Q4). However, adjusted (for age, gender, cognitive function, depressive status, Body Mass Index and grip strength) multiple linear regression showed that the omega-3 index-SPPB score association did not reach statistical significance [β = −0.166; (−0.346; 0.013); p = 0.07] in our sample. This cross-sectional study found that participants with a low omega-3 index had worse performance-based test results of physical function than people with a high omega-3 index, but this association did not reach statistical significance once confounders were controlled for. Studies looking at the over-time associations between PUFA status and physical performance changes may shed more light on this topic.
    Keywords: Fatty Acids ; Mapt ; Omega-3 ; Physical Performance ; Sppb ; Medicine ; Diet & Clinical Nutrition
    ISSN: 0261-5614
    E-ISSN: 1532-1983
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