| 1. |
- Fanin, Nicolas, et al.
(författare)
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Relative Importance of Climate, Soil and Plant Functional Traits During the Early Decomposition Stage of Standardized Litter
- 2020
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Ingår i: Ecosystems (New York. Print). - : Springer. - 1432-9840 .- 1435-0629. ; 23:5, s. 1004-1018
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Tidskriftsartikel (refereegranskat)abstract
- Climatic factors have long been considered predominant in controlling decomposition rates at large spatial scales. However, recent research suggests that edaphic factors and plant functional traits may play a more important role than previously expected. In this study, we investigated how biotic and abiotic factors interacted with litter quality by analyzing decomposition rates for two forms of standardized litter substitutes: green tea (high-quality litter) and red tea (low-quality litter). We placed 1188 teabags at two different positions (forest floor and 8 cm deep) across 99 forest sites in France and measured 46 potential drivers at each site. We found that high-quality litter decomposition was strongly related to climatic factors, whereas low-quality litter decomposition was strongly related to edaphic factors and the identity of the dominant tree species in the stand. This indicates that the relative importance of climate, soil and plant functional traits in the litter decomposition process depends on litter quality, which was the predominant factor controlling decomposition rate in this experiment. We also found that burying litter increased decomposition rates, and that this effect was more important for green tea in drier environments. This suggests that changes in position (surface vs. buried) at the plot scale may be as important as the role of macroclimate on decomposition rates because of varying water availability along the soil profile. Acknowledging that the effect of climate on decomposition depends on litter quality and that the macroclimate is not necessarily the predominant factor at large spatial scales is the first step toward identifying the factors regulating decomposition rates from the local scale to the global scale.
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| 2. |
- Redon, Paul-Olivier, et al.
(författare)
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Chloride and Organic Chlorine in Forest Soils: Storage, Resicence Times, and Influence of Ecological Conditons
- 2011
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Ingår i: Environmental Science and Technology. - Washington, DC, USA : American Chemical Society. - 0013-936X .- 1520-5851. ; 45:17, s. 7202-7208
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cltot) and organic chlorine (Clorg) were determined in litterfall, forest floor and mineral soil samples. Clorg constituted 11–100% of Cltot, with the highest concentrations being found in the humus layer (34–689 mg Clorg kg–1). In terms of areal storage (53 – 400 kg Clorg ha–1) the mineral soil dominated due to its greater thickness (40 cm). Clorg concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Clorg concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Clin) and organic) was 5-fold higher than that estimated for Clin alone. Consideration of the Clorg pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems.
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