| 1. |
- Lewandowska, A. M., et al.
(author)
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The influence of balanced and imbalanced resource supply on biodiversity-functioning relationship across ecosystems
- 2016
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In: Philosophical Transactions of the Royal Society B-Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 371:1694
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Journal article (peer-reviewed)abstract
- Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity ecosystern functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common pattems and differences in biodiversity functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity.
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| 2. |
- Venterink, H O, et al.
(author)
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Impact of drying and re-wetting on N, P and K dynamics in a wetland soil
- 2002
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In: Plant and Soil. - 0032-079X. ; 243:1, s. 119-130
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Journal article (peer-reviewed)abstract
- As increased nutrient availability due to drainage is considered a major cause of eutrophication in wetlands rewetting of drained wetlands is recommended as a restoration measure. The effect of soil drying and rewetting on the contribution of various nutrient release or transformation processes to changed nutrient availability for plants is however weakly understood. We measured effects of soil drying and re-wetting on N mineralization, and denitrification, as well as on release of dissolved organic nitrogen (DON), phosphorus, and potassium in incubated soil cores from a wet meadow in southern Sweden. Additionally, the impact of re-wetting with sulphate-enriched water was studied. Soil drying stimulated N mineralization (3 times higher) and reduced denitrification (5 times lower) compared to continuously wet soil. In the wet cores, denitrification increased to 20 mg N m(-2) d(-1), which was much higher than denitrification measured in the field. In the field, increased inorganic-N availability for plants due to drainage seemed primarily to be caused by increased N mineralization, and less by decreased denitrification. Soil drying also stimulated the release of DON and K, but P release was not affected. Re-wetting of dried soil cores strongly stimulated denitrification (up to 160 mg N m(-2) d(-1)), but N mineralization was not significantly decreased, neither were DON or K release. In contrast, the extractable P pool increased upon soil wetting. Re-wetting with sulphate-enriched water had no effect on any of the nutrient release or transformation rates. We conclude that caution is required in re-wetting of drained wetlands, because it may unintendently cause internal eutrophication through an increased P availability for plants.
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