Interactions between leaf nitrogen status and longevity in relation to N cycling in three contrasting European forest canopies

Wang, Liang; Ibrom, Andreas; Korhonen, Janne F. J.; Frumau, K.F.A.; Wu, Junjun; Pihlatie, Mari; Schjøerring, Jan K.

doi:10.5194/bg-10-999-2013

Cited by 24 publications

(23 citation statements)

References 56 publications

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“…These processes are seasonally programmed and closely linked to tree phenology (Wang et al 2013). The nitrogen economy of trees depends on the leaf lifespan and the efficiency of nitrogen resorption from senescing leaves (Yasumura et al 2002).…”

Section: Discussionmentioning

confidence: 99%

Proteolytic activity and nitrogen remobilisation in senescing leaves of phenological forms of Fagus sylvatica

Kraj¹

2014

Dendrobiology

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Leaf senescence allows plants to remobilise and use the same nitrogen repeatedly and is closely linked to autumn phenology. The timing of leaf senescence affects the growth rate and survival of trees due to the association between senescence and the remobilisation of nutrients, particularly nitrogen. The present study compares protein degradation dynamics and nitrogen remobilisation in early, intermediate and late phenological forms of beech trees (Fagus sylvatica L.). Specimens of phenological forms were marked and examined in 2005 and 2008. Leaf samples were collected from August to October during each of these years, and a biochemical analysis and a determination of proteolytic enzyme activity were conducted. The early phenological form showed protein degradation with three clearly indicated phases, whereas in the late form, protein degradation was stable with a constant decrease. The phenological forms differed significantly in their C/N ratios, which increased from approximately 20 in August to 37.5, 35 and 32 for the early, intermediate and late forms, respectively, at the end of leaf senescence. The date of the sudden drop in temperature had a decisive effect on the beginning of leaf senescence. Temperature has a greater effect on protein degradation and the protein and nitrogen resorption efficiency in the early form than in the late form. The trees that began to senesce the earliest exhibited the highest resorption of nitrogen compounds. Senescence led to an increase in proteolytic activity. Aminopeptidase activity was highest at the beginning of senescence, while endo-and carboxypeptidase activity was highest in the middle of senescence. The early form had the highest activity levels for all peptidase types. These results indicate that beech trees that differ in their autumn senescence timing display different nitrogen remobilisation efficiencies. This efficiency depended on the length of leaf senescence, peptidase activity and the sensitivity of particular phenological forms to temperature changes.

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Section: Discussionmentioning

confidence: 99%

Proteolytic activity and nitrogen remobilisation in senescing leaves of phenological forms of Fagus sylvatica

Kraj¹

2014

Dendrobiology

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“…6a and b), suggesting that F NH 3 decreases as LAI decreases, and that NH 3 emissions occur in the leaf fall period. Apart from decomposition of litter, also natural emissions of NH 3 linked to the leaf stomatal compensation point may cause NH 3 emissions to increase in the senescent period (Wang et al, 2011(Wang et al, , 2013. However such processes are not yet taken into account in the DAMOS system, and thus impacts of forest NH 3 emissions are not represented in the c NH 3 model calculations.…”

Section: Discussionmentioning

confidence: 99%

“…The forest component fluxes from the bi-directional NH 3 compensation point model indicated high emission fluxes from the ground layer following 30 October correlated to the atmospheric NH 3 emissions. The decreased deposition in the senescence period could also be caused by reduced leaf uptake of NH 3 through stomata, decreased cuticular desorption and larger NH 3 emission potential of the senescent leaves related to remobilisation of nitrogen during leaf senescence (Wang et al, 2011(Wang et al, , 2013. The bi-directional model showed a slightly decreased cuticular flux F w (Fig.…”

Section: Lai and Nh 3 Fluxes In The Leaf Fall Periodmentioning

confidence: 98%

Ammonia emissions from deciduous forest after leaf fall

et al. 2013

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The understanding of biochemical feedback mechanisms in the climate system is lacking knowledge in relation to bi-directional ammonia (NH₃) exchange between natural ecosystems and the atmosphere. We therefore study the atmospheric NH₃ fluxes during a 25-day period during autumn 2010 (21 October to 15 November) for the Danish beech forest Lille Bøgeskov to address the hypothesis that NH₃ emissions occur from deciduous forests in relation to leaf fall. This is accomplished by using observations of vegetation status, NH₃ fluxes and model calculations. Vegetation status was observed using plant area index (PAI) and leaf area index (LAI). NH₃ fluxes were measured using the relaxed eddy accumulation (REA) method. The REA-based NH₃ concentrations were compared to NH₃ denuder measurements. Model calculations of the atmospheric NH₃ concentration were obtained with the Danish Ammonia MOdelling System (DAMOS). The relative contribution from the forest components to the atmospheric NH₃ flux was assessed using a simple two-layer bi-directional canopy compensation point model. A total of 57.7% of the fluxes measured showed emission and 19.5% showed deposition. A clear tendency of the flux going from deposition of −0.25 ± 0.30 μg NH₃-N m⁻² s⁻¹ to emission of up to 0.67 ± 0.28 μg NH₃-N m⁻² s⁻¹ throughout the measurement period was found. In the leaf fall period (23 October to 8 November), an increase in the atmospheric NH₃ concentrations was related to the increasing forest NH₃ flux. Following leaf fall, the magnitude and temporal structure of the measured NH₃ emission fluxes could be adequately reproduced with the bi-directional resistance model; it suggested the forest ground layer (soil and litter) to be the main contributing component to the NH₃ emissions. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall, but during and after leaf fall, the modelled concentrations are too low. The results indicate that the missing contribution to atmospheric NH₃ concentration from vegetative surfaces related to leaf fall are of a relatively large magnitude. We therefore conclude that emissions from deciduous forests are important to include in model calculations of atmospheric NH₃ for forest ecosystems. Finally, diurnal variations in the measured NH₃ concentrations were related to meteorological conditions, forest phenology and the spatial distribution of local anthropogenic NH₃ sources. This suggests that an accurate description of ammonia fluxes over forest ecosystems requires a dynamic description of atmospheric and vegetation processes

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“…The re-translocation is directed either into woody roots and/or the trunks in deciduous species, or from previous years leaves into the youngest age class needles in conifers. Comparing three European forests subject to contrasting atmospheric N deposition loads, Wang et al (2013) found that this N re-translocation efficiency was lowest in a Douglas fir stand (37 %) subject to very large (45 kg N ha −1 yr −1 ) N deposition, compared to a temperate beech forest (70 %) and a boreal pine stand (62 %) exposed to much lower N deposition (ca. 20 and 5 kg N ha-1 yr −1 , respectively).…”

Section: Role Of Translocation On the Leaf Litter Nitrogen Content Ofmentioning

confidence: 99%

“…These processes ensure that large amounts of N remain available to the plant and are moderately protected against immobilisation in stable soil organic compounds or losses via leaching and gaseous emission (Wang et al, 2013). The N status of attached senescing leaves is controlled by the degree to which N is retranslocated from such leaves into the rest of the tree before leaf fall.…”

Section: Role Of Translocation On the Leaf Litter Nitrogen Content Ofmentioning

confidence: 99%

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

et al. 2013

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Atmospheric ammonia (NH₃) dominates global emissions of total reactive nitrogen (N_r), while emissions from agricultural production systems contribute about two-thirds of global NH₃ emissions; the remaining third emanates from oceans, natural vegetation, humans, wild animals and biomass burning. On land, NH₃ emitted from the various sources eventually returns to the biosphere by dry deposition to sink areas, predominantly semi-natural vegetation, and by wet and dry deposition as ammonium (NH₄⁺) to all surfaces. However, the land/atmosphere exchange of gaseous NH₃ is in fact bi-directional over unfertilized as well as fertilized ecosystems, with periods and areas of emission and deposition alternating in time (diurnal, seasonal) and space (patchwork landscapes). The exchange is controlled by a range of environmental factors, including meteorology, surface layer turbulence, thermodynamics, air and surface heterogeneous-phase chemistry, canopy geometry, plant development stage, leaf age, organic matter decomposition, soil microbial turnover, and, in agricultural systems, by fertilizer application rate, fertilizer type, soil type, crop type, and agricultural management practices. We review the range of processes controlling NH₃ emission and uptake in the different parts of the soil-canopy-atmosphere continuum, with NH₃ emission potentials defined at the substrate and leaf levels by different [NH₄⁺] / [H⁺] ratios (Γ). Surface/atmosphere exchange models for NH₃ are necessary to compute the temporal and spatial patterns of emissions and deposition at the soil, plant, field, landscape, regional and global scales, in order to assess the multiple environmental impacts of airborne and deposited NH₃ and NH₄⁺. Models of soil/vegetation/atmosphere NH₃ exchange are reviewed from the substrate and leaf scales to the global scale. They range from simple steady-state, "big leaf" canopy resistance models, to dynamic, multi-layer, multi-process, multi-chemical species schemes. Their level of complexity depends on their purpose, the spatial scale at which they are applied, the current level of parameterization, and the availability of the input data they require. State-of-the-art solutions for determining the emission/sink Γ potentials through the soil/canopy system include coupled, interactive chemical transport models (CTM) and soil/ecosystem modelling at the regional scale. However, it remains a matter for debate to what extent realistic options for future regional and global models should be based on process-based mechanistic versus empirical and regression-type models. Further discussion is needed on the extent and timescale by which new approaches can be used, such as integration with ecosystem models and satellite observations

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Interactions between leaf nitrogen status and longevity in relation to N cycling in three contrasting European forest canopies

Cited by 24 publications

References 56 publications

Proteolytic activity and nitrogen remobilisation in senescing leaves of phenological forms of Fagus sylvatica

Proteolytic activity and nitrogen remobilisation in senescing leaves of phenological forms of Fagus sylvatica

Ammonia emissions from deciduous forest after leaf fall

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

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