scholarly journals Mg isotope composition in beech forest ecosystems and variations induced by liming: insights from four experimental sites in Northern France

2021 ◽  
Author(s):  
Mélanie Court ◽  
Gregory van der Heijden ◽  
Pascale Louvat ◽  
Emile Bolou-Bi ◽  
Guillaume Caro ◽  
...  
2000 ◽  
Vol 151 (9) ◽  
pp. 317-324
Author(s):  
André Granier ◽  
Claire Damesin ◽  
Daniel Epron ◽  
Valérie Le Dantec

The results of an investigation carried through within the ‹Euroflux›-programme in eastern France assessing the carbon fluxes above the canopy of the forest are presented. The photosynthetic activity within the annual and daily cycles are discussed. The high variability of the carbon netbalance and the variation of the total respiration make further research into the understanding of the correlation between the carbon net-balance and the biomass production necessary.


2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Witoon Purahong ◽  
Michael Schloter ◽  
Marek J. Pecyna ◽  
Danuta Kapturska ◽  
Veronika Däumlich ◽  
...  

2012 ◽  
Vol 9 (11) ◽  
pp. 15633-15665
Author(s):  
K. Hansen ◽  
L. L. Sørensen ◽  
O. Hertel ◽  
C. Geels ◽  
C. A. Skjøth ◽  
...  

Abstract. The understanding of biochemical feed-back 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 days period during autumn 2010 (21 October–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 were obtained with the Danish Ammonia MOdelling System (DAMOS). 57.7% of the fluxes measured showed emission and 19.5% showed deposition. The mean NH3 flux was 0.087 ± 0.19 μg NH3-N m−2 s−1. A clear tendency of the flux going from negative (deposition) to positive (emission) fluxes of up to 0.96 ± 0.40 μg NH3-N m−2 s−1 throughout the measurement period was found. In the leaf fall period (23 October–8 November), an increase in the atmospheric NH3 concentrations was related to the increasing forest NH3 flux. The modelled concentration from DAMOS fits well the measured concentrations before leaf fall. 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.


2015 ◽  
Vol 57 (4) ◽  
pp. 233-239
Author(s):  
Sławomir Janyszek ◽  
Paweł Strzeliński ◽  
Magdalena Janyszek ◽  
Dorota Wrońska-Pilarek

Abstract The sequestration of carbon in biomass of herb and moss layers of forest ecosystems is relatively less studied, than analogical processes in trees biomass and soil organic mass. The paper presents mean values of carbon concentration and mean amounts of dry mass of plant material in the herb and moss layer of phytocoenoses formed under canopy of stands of main forest-forming species of trees in Poland. The parameters were studied for beech, birch, oak, alder, pine, fir and spruce forest stands, for most of the particular age classes. The studied plots were contained in following plant associations and communities: Ribo nigri-Alnetum, Fraxino-Alnetum, Galio odorati-Fagetum, Luzulo luzuloidis-Fagetum, Molinio caeruleae-Quercetum roboris, Calamagrostio-Quercetum petraeae, Abietetum polonicum, Abieti-Piceetum montanum, Calamagrostio villosae-Piceetum, as well as anthropogenic communities: Betula pendula comm. on Leucobryo-Pinetum habitat, Larix decidua comm. on Tilio-Carpinetum habitat, Pinus sylvestris comm. on Tilio-Carpinetum habitat, Picea abies comm. on Luzulo pilosae-Fagetum habitat (in lowland) and Picea abies comm. on Luzulo luzuloidis-Fagetum habitat (in lower mountain localities). The relatively highest carbon amount was observed in oak forests, pine forests and in older age classes of lowland beech forest, where the carbon concentration in dry mass reaches from 60 to 81%. The lowest concentrations were determined for lowland spruce forests, highland fir forests and for alder forests. The carbon concentration reached in these types of ecosystems from 39 to 41%.


2013 ◽  
Vol 10 (7) ◽  
pp. 4577-4589 ◽  
Author(s):  
K. Hansen ◽  
L. L. Sørensen ◽  
O. Hertel ◽  
C. Geels ◽  
C. A. Skjøth ◽  
...  

Abstract. 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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