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- Akselsson, Cecilia, et al.
(författare)
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Assessing the risk of N leaching from forest soils across a steep N deposition gradient in Sweden.
- 2010
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 158:12, s. 3588-3595
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen leaching from boreal and temporal forests, where normally most of the nitrogen is retained, has the potential to increase acidification of soil and water and eutrophication of the Baltic Sea. In parts of Sweden, where the nitrogen deposition has been intermediate to high during recent decades, there are indications that the soils are close to nitrogen saturation. In this study, four different approaches were used to assess the risk of nitrogen leaching from forest soils in different parts of Sweden. Nitrate concentrations in soil water and C:N ratios in the humus layer where interpreted, together with model results from mass balance calculations and detailed dynamic modelling. All four approaches pointed at a risk of nitrogen leaching from forest soils in southern Sweden. However, there was a substantial variation on a local scale. Basing the assessment on four different approaches makes the assessment robust.
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- Belyazid, Salim, et al.
(författare)
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A dynamic modelling approach for estimating critical loads of nitrogen based on pliant community changes under a changing climate
- 2011
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491. ; 159:3, s. 789-801
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Tidskriftsartikel (refereegranskat)abstract
- A dynamic model of forest ecosystems was used to investigate the effects of climate change, atmospheric deposition and harvest intensity on 48 forest sites in Sweden (n = 16) and Switzerland (n = 32). The model was used to investigate the feasibility of deriving critical loads for nitrogen (N) deposition based on changes in plant community composition. The simulations show that climate and atmospheric deposition have comparably important effects on N mobilization in the soil, as climate triggers the release of organically bound nitrogen stored in the soil during the elevated deposition period. Climate has the most important effect on plant community composition, underlining the fact that this cannot be ignored in future simulations of vegetation dynamics. Harvest intensity has comparatively little effect on the plant community in the long term, while it may be detrimental in the short term following cutting. This study shows: that critical loads of N deposition can be estimated using the plant community as an indicator; that future climatic changes must be taken into account; and that the definition of the reference deposition is critical for the outcome of this estimate. (C) 2010 Elsevier Ltd. All rights reserved.
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| 5. |
- Belyazid, Salim, et al.
(författare)
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Exploring Ground Vegetation Change for Different Deposition Scenarios and Methods for Estimating Critical Loads for Biodiversity Using the ForSAFE-VEG Model in Switzerland and Sweden
- 2011
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 1573-2932 .- 0049-6979. ; 216:1-4, s. 289-317
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Tidskriftsartikel (refereegranskat)abstract
- The ForSAFE-VEG model was used to investigate the impacts of climate change and air pollution scenarios on soil chemistry and ground vegetations composition. In particular, the model involves a ground vegetation model incorporating plant changes to ambient site conditions in terms of climate and chemistry, but the model also incorporate competition between the different plant groups. The model was validated against observed values and reproduced observations of tree growth, soil chemistry, and ground vegetation compositions to satisfaction. The results show that the ground vegetation reacts strongly to changes in air pollution, in particular nitrogen as well as to climate change with major shifts in plant composition. A procedure for estimating critical loads for nitrogen, using ground vegetation biodiversity as criterion, was tested and the method seems operable. It suggests that if we want to protect the present biodiversity of the ground vegetation, this will face significant difficulties because of permanent climate change that induced changes in the ecosystem. We conclude that the reference state for ground vegetation biodiversity is rather to be sought for in the future, hopefully using models, than in the past or present.
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| 8. |
- De Vries, W., et al.
(författare)
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Use of dynamic soil-vegetation models to assess impacts of nitrogen deposition on plant species composition: an overview
- 2010
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761. ; 20:1, s. 60-79
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Tidskriftsartikel (refereegranskat)abstract
- Field observations and experimental data of effects of nitrogen (N) deposition oil plant species diversity have been Used to derive empirical critical N loads for various ecosystems. The great advantage of such an approach is the inclusion of field evidence, but there are also restrictions, such as the absence of explicit criteria regarding significant effects on the vegetation, and the impossibility to predict future impacts when N deposition changes. Model approaches Call account for this. In this paper, we review the possibilities of static and dynamic multispecies models in combination with dynamic soil-vegetation models to (1) predict plant species composition as a function of atmospheric N deposition and (2) calculate critical N loads in relation to a prescribed protection level of the species composition. The similarities between the models are presented, but also several important differences, including the Use of different indicators for N and acidity and the prediction of individual plant species VS. Plant communities. A summary of the strengths and weaknesses of the various Models, including their validation status, is given. Furthermore,. examples are given of critical load calculations with the model chains and their comparison with empirical critical N loads. We show that linked biogeochemistry-biodiversity models for N have potential for applications to support European policy to reduce N input, but the definition of damage thresholds for terrestrial biodiversity represents a major challenge. There is also a clear need for further testing and validation of the models against long-term monitoring or long-term experimental data sets and against large-scale survey data. This requires a focused data collection ill Europe. combing vegetation descriptions with variables affecting the species diversity. such as Soil acidity, nutrient status and water availability. Finally there is a need for adaptation and upscaling of the models beyond the regions for which dose-response relationships have been parameterized, to make them generally applicable.
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| 10. |
- Phelan, Jennifer, et al.
(författare)
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Estimation of Soil Base Cation Weathering Rates with the PROFILE Model to Determine Critical Loads of Acidity for Forested Ecosystems in Pennsylvania, USA: Pilot Application of a Potential National Methodology
- 2014
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 1573-2932 .- 0049-6979. ; 225:9, s. 2109-2109
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Tidskriftsartikel (refereegranskat)abstract
- Base cation weathering (BCw) rate is one of the most influential yet difficult to estimate parameters in the calculation of critical acid loads of nitrogen (N) and sulfur (S) deposition for terrestrial systems. Only the clay correlation-substrate method, a simple empirical model, has been used for estimating BCw rates for forest ecosystems in the conterminous USA and may not be suitable for application at all sites without calibration or revision. An alternate model, PROFILE, may offer an improved method to estimate BCw rates. It is a transferable, process-based model that simulates the weathering rates of groups of minerals. The objective of this study was to evaluate PROFILE using national datasets as a method to estimate BCw rates for forests in the USA, focusing on Pennsylvania (PA) as the first test state. The model paired with national datasets was successfully applied at 51 forested sites across PA. Weathering rates ranged from 119 to 9,245 eq ha(-1) year(-1) and were consistent with soil properties and regional geology. Comparisons of terrestrial critical acid loads with 2002 N and S deposition showed critical load exceedances at 53 % of the sites. This trial evaluation of PROFILE paired with national datasets in PA establishes that there are sufficient data to support the estimation of BCw rates and determination of critical acid loads for forests in the USA. However, the paired method should be applied in other locations to further evaluate the performance of the model in different regions of the country.
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