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  • Elsevier (CrossRef)  (61)
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  • 1
    Language: English
    In: Forest Ecology and Management, 2011, Vol.262(2), pp.105-114
    Description: ► Competition for N between young and adult beech is reduced by seasonal timing. ► Beech seedlings favour N uptake in spring, adult beech trees in autumn. ► Removal of vegetation components does not play a role in this competition. ► Competition between plants and soil microorganisms is, therefore, not avoided. Plant growth, reproduction, and biomass allocation may be affected differently by nitrogen availability depending on tree size and age. In this context, competition for limited N may be avoided by different strategies of N acquisition between different vegetation components (i.e., seedlings, mature trees, other woody and herbaceous understorey). This study investigated in a field experiment whether the competition for N between different vegetation components in beech forests was prevented via seasonal timing of N uptake and affected by microbial N use. For this purpose, a removal approach was used to study the seasonal effects on N uptake and N metabolites in adult beech trees and beech natural regeneration, as well as soil microbial processes of inorganic N production and utilisation. We found that the competition for N between beech natural regeneration and mature beech trees was reduced by seasonal avoidance strategies (“good parenting”) of N uptake regardless of the N sources used. In spring, organic and inorganic N uptake capacity was significantly higher in beech seedlings compared to adult beech trees, whereas in autumn mature beech trees showed the highest N uptake rates. Removal of vegetation components did not result in changes in soil microbial N processes in the course of the growing season. Thus, N resources released by the removal of vegetation components were marginal. This consistency in soil microbial N processes indicates that competition between plants and soil microorganisms for N was not avoided by timing of acquisition during the vegetation period, but existed during the entire growing season. In conclusion, N nutrition in the studied forest ecosystem seems to be optimally attuned to European beech.
    Keywords: Fagus Sylvatica ; N Uptake ; N Metabolites ; Soil Microorganisms ; Soil N Processes ; Removal Approach ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 2
    Language: English
    In: Forest Ecology and Management, 01 December 2012, Vol.285, pp.227-238
    Description: ► δ C- and δ O- signatures of tree-rings were used to assess forest management. ► One site showed pronounced differences in δ C between early- and latewood. ► Here, greater productivity was related to greater flexibility in water use efficiency. ► δ O-signatures acted as a proxy record of Vapor Pressure Deficit (VPD). ► The slope of the correlation between δ O and WUE indicated stomatal sensitivity to VPD. Foresters frequently lack sufficient information about site quality to optimize plantation management and logwood production to local conditions. In the present study we explored the potential of δ C- and δ O-signatures of tree-rings to provide such information. We studied stem disks collected from two plantations in south-eastern Australia that had been thinned or treated with fertilizer. Estimated from tree-ring δ C, the sites differed markedly in intrinsic water use efficiency of photosynthesis (WUE = / ). Stem disks from one site (Lyons) showed pronounced differences in δ C between early- and latewood, depending on stand density. Fertilizer application subsequent to thinning transiently increased foliage-N concentrations, without additional effects on and δ C. Thinning (and fertilization) at the other site (Daylesford) had little effect on δ C-variation between early- and late wood. Greater productivity at Lyons is seemingly related to greater flexibility in WUE such that fluctuating water supply was more efficiently exploited. Current theory suggests δ O-signatures in wood at this site acted as a proxy record of Vapor Pressure Deficit (VPD), and the slope of the correlation between δ O and WUE (as an indicator of stomatal sensitivity to VPD) helped identify growth limiting resources and conditions. In general, δ O and WUE were positively correlated and WUE seemed mainly under stomatal control. Employing a General Linear Model, we identified additional influences on WUE . The slope, and closeness of fit of the correlation between δ O and WUE depended on stand density, wood type (early- or late wood), and individual trees. These traits were not correlated in early wood immediately after planting, suggesting WUE was driven by biochemical demand for CO in photosynthesis. Conversely, enhanced competition for soil water after canopy closure resulted in positive correlations between δ O and WUE , indicating enhanced importance of stomatal resistance to CO -diffusion. We discuss the limitations to the use of δ C- and δ O analysis of bulk wood for determining the balance between demand- and supply-driven control of WUE .
    Keywords: Pinus Radiata ; Plantation Management ; Thinning ; Fertilization ; Stable Isotopes ; Δ13c and Δ18o ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 3
    Language: English
    In: Soil Biology and Biochemistry, January 2015, Vol.80, pp.92-117
    Description: NO emissions from soils and ecosystems are of outstanding importance for atmospheric chemistry. Here we review the current knowledge on processes involved in the formation and consumption of NO in soils, the importance of NO for the physiological functioning of different organisms, and for inter- and intra-species signaling and competition, e.g. in the rooting zone between microbes and plants. We also show that prokaryotes and eukaryotes are able to produce NO by multiple pathways and that unspecific enzymo-oxidative mechanisms of NO production are likely to occur in soils. Nitric oxide production in soils is not only linked to NO production by nitrifying and denitrifying microorganisms, but also linked to extracellular enzymes from a wide range of microorganisms. Further investigations are needed to clarify molecular mechanisms of NO production and consumption, its controlling factors, and the significance of NO as a regulator for microbial, animal and plant processes. Such process understanding is required to elucidate the importance of soils as sources (and sinks) for atmospheric NO.
    Keywords: Nitric Oxide ; Unspecific Enzymo-Oxidative Mechanisms ; Nos ; Sod ; Dissimilatory Nitrate Reduction to Ammonium ; No Signaling ; No Consumption ; No Production ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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  • 4
    Language: English
    In: Environmental Pollution, September 2016, Vol.216, pp.773-785
    Description: Growth and development of plants largely depends on their adaptation ability in a changing climate. This is particularly true on heavy metal contaminated soils, but the interaction of heavy metal stress and climate on plant performance has not been intensively investigated. The aim of the present study was to elucidate if transgenic poplars ( . ) with enhanced glutathione content possess an enhanced tolerance to drought and lead (Pb) exposure (single and in combination) and if they are good candidates for phytoremediation of Pb contaminated soil. Lead exposure reduced growth and biomass accumulation only in above-ground tissue of wild type poplar, although most of lead accumulated in the roots. Drought caused a decline of the water content rather than reduced biomass production, while Pb counteracted this decline in the combined exposure. Apparently, metals such as Pb possess a protective function against drought, because they interact with abscisic acid dependent stomatal closure. Lead exposure decreased while drought increased glutathione content in leaves of both plant types. Lead accumulation was higher in the roots of transgenic plants, presumably as a result of chelation by glutathione. Water deprivation enhanced Pb accumulation in the roots, but Pb was subject to leakage out of the roots after re-watering. Transgenic plants showed better adaptation under mild drought plus Pb exposure partially due to improved glutathione synthesis. However, the transgenic plants cannot be considered as a good candidate for phytoremediation of Pb, due to its small translocation to the shoots and its leakage out of the roots upon re-watering. The present study improves our understanding of the combined effects of lead and drought stress on plant growth and contributes to a better selection of plants for phytoremediation.
    Keywords: Water Deprivation ; Ros ; Re-Watering ; Glutathione ; Phytoremediation ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 5
    Language: English
    In: Forest Ecology and Management, 2010, Vol.259(6), pp.1190-1199
    Description: We examined water use by maturing , growing with or without an mid-storey stratum of spp. ( or . ), for 〉180 consecutive days. Study sites were located in the Upper Yarra catchment area in south-eastern Australia. Depending on their contribution to stand basal area, mid-storey spp. increased total stand water use by up to 30%. Monthly water use in such stands reached more than 640,000 L ha (compared to 545,000 L ha in stands where acacias were absent) in early spring. Water use was curvilinearly related to sapwood area of spp. and logistically related to sapwood area of . . Water use of all three species showed a strong relation to daily maximum air temperatures. Distinct and simple relationships provide clear guides to the likely impacts of climate change and forest management on water yield. We compared a traditional up-scaling approach, from individual tree water use to stand water use, to a new approach that incorporates variation in temperature. Development of this approach can lead to greater precision of stand water use estimates – and in turn catchment water yield – under current climate change scenarios, which predict a rise in air temperatures of 0.6–2.5 °C by 2050 for the study area. Our temperature-dependent approach suggests that under conditions of non-limiting water availability, stand water use will rise by 2% for every 0.25 °C increase in maximum air temperatures during winter, and possibly more than that during summer.
    Keywords: Eucalyptus Regnans ; Acacia Dealbata ; Acacia Melanoxylon ; Tree Water Use ; Stand Structure ; Water Management ; Climate Change ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 6
    Language: English
    In: Forest Ecology and Management, 01 July 2012, Vol.275, pp.60-67
    Description: ► We study two adult populations under different microclimatic conditions. ► We compare genetic diversity of the adult populations and their natural regeneration. ► Case study based on isozymes and microsatellite markers. ► We identified two “outlier microsatellite loci”, exhibiting directional selection. ► Natural selection account for different genetic structures of the adult populations. Due to its drought sensitivity, the performance and competitiveness of beech as a favoured species of forest management in Central Europe is likely to be negatively affected by the prognosticated climate change, leading to major impacts on the vulnerability of managed forest ecosystems. We studied the genetic differentiation between two populations from a relatively cold and wet northeast (representing the current climate of the majority of beech forests in Central Europe) and a relatively warm and dry southwest facing slope (representing the future climate of an increasing area covered by beech forests in Central Europe) at the same forest site to investigate the adaptation processes in these two populations under different microclimatic conditions. For this purpose, two different techniques, , nuclear microsatellites (neutral) and isozyme markers (adaptive), were applied to adult trees and natural regeneration at both slopes. Although microsatellites are considered to be neutral markers, they have been shown in several studies to give signals of selectively-driven changes. In our study, two of the five microsatellites behaved as “outlier loci”, exhibiting directional selection. Our results show independent of the technique applied that natural regeneration of the southwest slope and the natural regeneration and adult trees of the northeast slope were genetically closer than the adult trees from the southwest slope. Thus, we conclude that natural selection and potential adaptation account for genetic changes and different genetic structures among the two adult populations in this case study.
    Keywords: Fagus Sylvatica ; Climate Change ; Isozymes ; Nuclear Microsatellites ; Beech ; Adaptation ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 7
    Language: English
    In: Forest Ecology and Management, 01 April 2017, Vol.389, pp.46-58
    Description: The Loess Plateau in China constitutes an area short of soil nitrogen and organic carbon due to local land degradation induced by various factors (i.e. long term changes of land use, climate conditions, and soil properties). The present study aimed to examine the effects of species and land management by afforestation on tree N acquisition capacity and soil N and C availability in degraded soils of the Loess Plateau area. We quantified root N uptake of inorganic and organic N sources as well as soil N and C availability, both at the tree species (i.e. L., L. and Carr.) and the land management (i.e. arable vs. monoculture vs. mixed afforested stands) levels. Our results indicated that afforestation improved soil N and organic C availabilities compared to abandoned arable land ( 〈 0.05). In particular, the presence of N -fixing enhanced root N concentrations (ca. 3.0 times) and soil NO (ca. 5.4 times), soil total N (ca. 1.9 times) and organic C (ca. 3.4 times) availabilities, but decreased soil NH (ca. −33%), microbial biomass carbon (ca. −74%) and nitrogen (ca. −54%) in the mixed stand compared to monoculture. Under the experimental conditions applied, the afforested trees preferred organic over inorganic N compounds as well as NO over NH ; in monoculture had a highest root amino acids N uptake capacities (i.e. 76.6 ± 7.7 nmol N (g fw) h for glutamine, 90.3 ± 8.9 nmol N (g fw) h for arginine) compared to other tree species whereas such high uptake capacities were largely repressed in the mixed stand with . Thus, in the Loess Plateau area, the inter-planting system of with N -fixing could improve the total soil N and organic C pools as well as plant N cycling compared to traditional arable land use and monoculture system. This study shows that inter-planting with economic fruit trees can be considered a successful strategy for soil regeneration by afforestation in future land management projects.
    Keywords: Root N Uptake ; Soil N Availability ; Monoculture ; Mixed Stand ; Degraded Soil ; Afforestation ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 8
    Language: English
    In: Environmental Pollution, June 2018, Vol.237, pp.205-217
    Description: Energy crops are an important renewable source for energy production in future. To ensure high yields of crops, N fertilization is a common practice. However, knowledge on environmental impacts of bioenergy plantations, particularly in systems involving trees, and the effects of N fertilization is scarce. We studied the emission of volatile organic compounds (VOC), which negatively affect the environment by contributing to tropospheric ozone and aerosols formation, from and willow plantations. Particularly, we aimed at quantifying the effect of N fertilization on VOC emission. For this purpose, we determined plant traits, photosynthetic gas exchange and VOC emission rates of the two systems as affected by N fertilization (0 and 80 kg ha yr ). Additionally, we used a modelling approach to simulate (i) the annual VOC emission rates as well as (ii) the OH reactivity resulting from individual VOC emitted. Total VOC emissions from was 1.5- and 2.5-fold higher compared to in non-fertilized and fertilized plantations, respectively. Isoprene was the dominating VOC in (80–130 μg g DW h ), whereas it was negligible in . We identified twenty-eight VOC compounds, which were released by with the green leaf volatile hexanal as well as dimethyl benzene, dihydrofuranone, phenol, and decanal as the dominant volatiles. The pattern of VOC released from this species clearly differed to the pattern emitted by . OH reactivity from VOC released by was ca. 8-times higher than that of . N fertilization enhanced stand level VOC emissions, mainly by promoting the leaf area index and only marginally by enhancing the basal emission capacity of leaves. Considering the higher productivity of fertilized compared to together with the considerably lower OH reactivity per weight unit of biomass produced, qualified the C -perennial grass as a superior source of future bioenergy production. N fertilization strongly increased VOC emission of but not of at the plantation level, making the latter a superior source of future bioenergy production.
    Keywords: Biogenic VOC Emissions ; Greenhouse Gas ; Plant Growth ; N Availability ; Bioenergy Crops ; Salix ; Miscanthus ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 9
    Language: English
    In: Environmental Pollution, November 2018, Vol.242, pp.905-913
    Description: Vegetation in the Arabian Peninsula is facing high and steadily rising tropospheric ozone pollution. However, little is known about the impacts of elevated ozone on date palms, one of the most important indigenous economic species. To elucidate the physiological responses of date palm to peak levels of acute ozone exposure, seedlings were fumigated with 200 ppb ozone for 8 h. Net CO assimilation rate, stomatal conduction, total carbon, its isotope signature and total sugar contents in leaves and roots were not significantly affected by the treatment and visible symptoms of foliar damage were not induced. Ozone exposure did not affect hydrogen peroxide and thiol contents but diminished the activities of glutathione reductase and dehydroascorbate reductase, stimulated the oxidation of ascorbate, and resulted in elevated total ascorbate contents. Total nitrogen, soluble protein and lignin contents remained unchanged upon ozone exposure, but the abundance of low molecular weight nitrogen (LMWN) compounds such as amino acids and nitrate as well as other anions were strongly diminished in leaves and roots. Other nitrogen pools did not benefit from the decline of LMWN, indicating reduced uptake and/or enhanced release of these compounds into the soil as a systemic response to aboveground ozone exposure. Several phenolic compounds, concurrent with fatty acids and stearyl alcohol, accumulated in leaves, but declined in roots, whereas total phenol contents significantly increased in the roots. Together these results indicate that local and systemic changes in both, primary and secondary metabolism contribute to the high tolerance of date palms to short-term acute ozone exposure. Date palms can grow and develop in an environment with high acute atmospheric ozone levels due to its tolerance to this air pollutant mediated by adaptations of both, primary and secondary metabolisms, as well as whole plant shoot-root interactions.
    Keywords: Sugars ; Reactive Oxygen Species ; Glutathione ; Ascorbate ; Nitrate ; Nitrogen Partitioning ; Anti-Oxidative System ; Secondary Metabolites ; Engineering ; Environmental Sciences ; Anatomy & Physiology
    ISSN: 0269-7491
    E-ISSN: 1873-6424
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  • 10
    Language: English
    In: FEBS Letters, 03 June 2010, Vol.584(11), pp.2271-2278
    Description: A key step in sulfate assimilation into cysteine is the reduction of sulfite to sulfide by sulfite reductase (SiR). This enzyme is encoded by three genes in the moss . To obtain a first insight into the roles of the individual isoforms, we deleted the gene encoding the isoform in by homologous recombination and subsequently analysed the Δ mutants. While Δ mutants showed no obvious alteration in sulfur metabolism, their regeneration from protoplasts and their ability to produce mature spores was significantly affected, highlighting an unexpected link between moss sulfate assimilation and development, that is yet to be characterized.
    Keywords: Bryophyte ; Moss Development ; Protonema Development ; Spore Maturation ; Sulfate Assimilation ; Biology ; Chemistry ; Anatomy & Physiology
    ISSN: 0014-5793
    E-ISSN: 1873-3468
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