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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: 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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  • 4
    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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  • 5
    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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  • 6
    Language: English
    In: Forest Ecology and Management, 2009, Vol.257(3), pp.1157-1164
    Description: Due to its wide European distribution and its drought-susceptibility, beech ( L.) received intensive attention recently in the light of global warming. Contrary to central European beech ecosystems, little is known about the ecophysiology of beech at its south-eastern European distribution limit. Here we tested whether climatic fluctuations during a three-year period affected the ecophysiology of a beech site in Greece. Attention was paid at comparing our findings to the intense effects the 2003 extreme drought had on beech forests in central Europe. We assessed the interannual and seasonal variation of certain physiological parameters in a beech stand of north-western Greece during three consecutive growing seasons of the period 2003–2005. Leaf water potential and effective quantum yield of PSII were measured as well-known indicators of plant's responses to environmental stresses. Furthermore, plant carbon isotopic composition (δ C) of tissues and extracts with different turnover times was determined, since it can reveal short- or long-term environmental effects on the water and carbon balance of the plant. Moreover, a number of micrometeorological parameters were measured and their effect on ecophysiological responses was tested. Precipitation of 2003 at the study site was comparable to that in central Europe, but it did not differ from the local range of precipitation in NW-Greece. Still, 2003 was more xeric, compared to 2004 and 2005. Despite this, leaf water potential, effective quantum yield and δ O showed no significant variation between years and their values were not indicative of plants suffering from drought stress. Foliar δ C, on the other hand, appeared to be more sensitive to the climatic differences between the years and it was higher during the more xeric 2003 compared to later on. Regression analysis revealed that its response was largely controlled by current soil water content and vapour pressure deficit of the preceding month. Regarding δ C of phloem from both twigs and trunk, their patterns were influenced only by short-term changes in air vapour pressure deficit. Within the climatic range recorded in this study, which is typical for beech ecosystems in Greece, no substantial drought-driven limitations were observed on beech ecophysiology. Our observations contradict those from central European beech sites, rarely subjected to drought, where similarly low water availability had a great impact on the ecophysiology of beech.
    Keywords: Carbon Isotopes ; Effective Quantum Yield ; Fagus Sylvatica ; Leaf Water Potential ; South-Eastern Europe ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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