| 1. |
- Acosta, Manuel, et al.
(author)
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Soil surface CO2 efflux measurements in Norway spruce forests: Comparison between four different sites across Europe - from boreal to alpine forest
- 2013
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In: Geoderma. - : Elsevier BV. - 0016-7061. ; 192, s. 295-303
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Journal article (peer-reviewed)abstract
- Extensive measurements of soil surface (including vegetation cover) CO2 efflux were carried out on 80 positions at four different forest sites (Sweden, Germany, Czech Republic and Italy) using a closed dynamic chamber technique. The period of measurement was 4-5 consecutive days per site. Two approaches were used to analyze the measured data, the Q(10) parameter and the Arrhenius relationship. Basic environmental factors such as soil temperature and moisture were measured. All the four investigated sites showed a positive dependence of the soil surface CO2 efflux on soil temperature. The four datasets generally resulted in good agreement (up to 93%) between the approaches and residual analysis showed no significant difference between approaches (less than 8%). The Q(10) ranged between 2.0 and 23 among the sites. The highest spatial variation of the soil surface CO2 efflux at 10 degrees C (expressed by the coefficient of variation CV) ranged from 30 to 65% between sites. (C) 2012 Elsevier B.V. All rights reserved.
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| 2. |
- Balzarolo, Manuela, et al.
(author)
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Ground-Based Optical Measurements at European Flux Sites: A Review of Methods, Instruments and Current Controversies
- 2011
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In: Sensors. - : MDPI AG. - 1424-8220. ; 11:8, s. 7954-7981
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Research review (peer-reviewed)abstract
- This paper reviews the currently available optical sensors, their limitations and opportunities for deployment at Eddy Covariance (EC) sites in Europe. This review is based on the results obtained from an online survey designed and disseminated by the Co-cooperation in Science and Technology (COST) Action ESO903-"Spectral Sampling Tools for Vegetation Biophysical Parameters and Flux Measurements in Europe" that provided a complete view on spectral sampling activities carried out within the different research teams in European countries. The results have highlighted that a wide variety of optical sensors are in use at flux sites across Europe, and responses further demonstrated that users were not always fully aware of the key issues underpinning repeatability and the reproducibility of their spectral measurements. The key findings of this survey point towards the need for greater awareness of the need for standardisation and development of a common protocol of optical sampling at the European EC sites.
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| 3. |
- Flechard, Chris R., et al.
(author)
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Carbon-nitrogen interactions in European forests and semi-natural vegetation - Part 1: Fluxes and budgets of carbon, nitrogen and greenhouse gases from ecosystem monitoring and modelling
- 2020
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In: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:6, s. 1583-1620
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Journal article (peer-reviewed)abstract
- The impact of atmospheric reactive nitrogen (N-r) deposition on carbon (C) sequestration in soils and biomass of unfertilized, natural, semi-natural and forest ecosystems has been much debated. Many previous results of this dC/dN response were based on changes in carbon stocks from periodical soil and ecosystem inventories, associated with estimates of N-r deposition obtained from large-scale chemical transport models. This study and a companion paper (Flechard et al., 2020) strive to reduce uncertainties of N effects on C sequestration by linking multi-annual gross and net ecosystem productivity estimates from 40 eddy covariance flux towers across Europe to local measurement-based estimates of dry and wet N-r deposition from a dedicated collocated monitoring network. To identify possible ecological drivers and processes affecting the interplay between C and N-r inputs and losses, these data were also combined with in situ flux measurements of NO, N2O and CH4 fluxes; soil NO3- leaching sampling; and results of soil incubation experiments for N and greenhouse gas (GHG) emissions, as well as surveys of available data from online databases and from the literature, together with forest ecosystem (BAS-FOR) modelling. Multi-year averages of net ecosystem productivity (NEP) in forests ranged from -70 to 826 gCm(-2) yr(-1) at total wet + dry inorganic N-r deposition rates (N-dep) of 0.3 to 4.3 gNm(-2) yr(-1) and from -4 to 361 g Cm-2 yr(-1) at N-dep rates of 0.1 to 3.1 gNm(-2) yr(-1) in short semi-natural vegetation (moorlands, wetlands and unfertilized extensively managed grasslands). The GHG budgets of the forests were strongly dominated by CO2 exchange, while CH4 and N2O exchange comprised a larger proportion of the GHG balance in short semi-natural vegetation. Uncertainties in elemental budgets were much larger for nitrogen than carbon, especially at sites with elevated N-dep where N-r leaching losses were also very large, and compounded by the lack of reliable data on organic nitrogen and N-2 losses by denitrification. Nitrogen losses in the form of NO, N2O and especially NO3- were on average 27%(range 6 %-54 %) of N-dep at sites with N-dep < 1 gNm(-2) yr(-1) versus 65% (range 35 %-85 %) for N-dep > 3 gNm(-2) yr(-1). Such large levels of N-r loss likely indicate that different stages of N saturation occurred at a number of sites. The joint analysis of the C and N budgets provided further hints that N saturation could be detected in altered patterns of forest growth. Net ecosystem productivity increased with N-r deposition up to 2-2.5 gNm(-2) yr(-1), with large scatter associated with a wide range in carbon sequestration efficiency (CSE, defined as the NEP/GPP ratio). At elevated N-dep levels (> 2.5 gNm(-2) yr(-1)), where inorganic N-r losses were also increasingly large, NEP levelled off and then decreased. The apparent increase in NEP at low to intermediate N-dep levels was partly the result of geographical cross-correlations between N-dep and climate, indicating that the actual mean dC/dN response at individual sites was significantly lower than would be suggested by a simple, straightforward regression of NEP vs. N-dep.
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| 4. |
- Jurasinski, Gerald, et al.
(author)
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Active afforestation of drained peatlands is not a viable option under the EU Nature Restoration Law
- 2024
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In: AMBIO. - 0044-7447 .- 1654-7209. ; 53:7, s. 970-983
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Journal article (peer-reviewed)abstract
- The EU Nature Restoration Law (NRL) is critical for the restoration of degraded ecosystems and active afforestation of degraded peatlands has been suggested as a restoration measure under the NRL. Here, we discuss the current state of scientific evidence on the climate mitigation effects of peatlands under forestry. Afforestation of drained peatlands without restoring their hydrology does not fully restore ecosystem functions. Evidence on long-term climate benefits is lacking and it is unclear whether CO2 sequestration of forest on drained peatland can offset the carbon loss from the peat over the long-term. While afforestation may offer short-term gains in certain cases, it compromises the sustainability of peatland carbon storage. Thus, active afforestation of drained peatlands is not a viable option for climate mitigation under the EU Nature Restoration Law and might even impede future rewetting/restoration efforts. Instead, restoring hydrological conditions through rewetting is crucial for effective peatland restoration.
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