The influence of long-term soil warming and increased nitrogen availability on carbon dynamics of subarctic grasslands
Abstract: Stopping climate change is one of the greatest challenges of our generation, and soil, though overlooked by many, can be a substantial part of both the solution and the problem. More than a third of the world's carbon (C) stocks are stored in soils in the form of soil organic matter (...
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| Other Authors: | , |
| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2021
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| Online Access: | https://hdl.handle.net/10067/1837420151162165141 https://repository.uantwerpen.be/docstore/d:irua:9558 |
| Summary: | Abstract: Stopping climate change is one of the greatest challenges of our generation, and soil, though overlooked by many, can be a substantial part of both the solution and the problem. More than a third of the world's carbon (C) stocks are stored in soils in the form of soil organic matter (SOM), which is more than in vegetation and the atmosphere combined. Climate warming may on the one hand accelerate the release of C from soils in the form of CO2, but on the other hand increase the productivity of autotrophs, mainly plants, leading to increased CO2 uptake. The position of this balance is crucial and determines whether soil finally releases or absorbs C and thus amplifies or mitigates climate warming. Warming influences SOM decomposition rate and plant productivity, but the warming effect can be modified by (changes in) nutrient availability. Nitrogen has been shown to inhibit plant growth when deficient, thus negating the expected productivity increase. Although N is released during the decomposition of SOM, it has been shown that soil warming reduces the N retention capacity of soil microbes, resulting in a large part being lost. This can lead to N limitation in plants, and a smaller than expected increase in productivity. Northern ecosystems contain a disproportionate amount of soil C, but also warm up disproportionately fast, making them a crucial link in soil research. In addition, a geothermal temperature gradient on a grassland in Iceland provided a unique opportunity to analyse the effect of warming, warming duration and N availability on ecosystem dynamics and soil C storage. In this PhD thesis, the effects of warming and increased N availability on plant productivity and soil C inputs, microbial community dynamics and SOM stabilisation, storage and degradation were analysed. Warming accelerated C-fluxes through the ecosystem, led to increased C inputs into the soil by plants, but reduced soil C storage. Although warming also depleted soil nitrogen, presumably resulting in increased N limitation in ... |
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