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The impact of nitrogen fertilisation and salinity treatments on populations of Elymus athericus on Schiermonnikoog

Vries, A.B. de (2001) The impact of nitrogen fertilisation and salinity treatments on populations of Elymus athericus on Schiermonnikoog. Master's Thesis / Essay, Biology.

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Elymus athericus has extended its distribution within the Wadden Sea salt marshes over the past 20 years. In the upper marsh, Elymus species almost form a monoculture and also the lower marsh with higher salinity stress is being invaded. In the salt marsh soil salinity is thought to be the major stress factor for plant growth. Plants can develop different mechanisms to cope with salt stress and one of them is the production of organic solutes, which contain nitrogen. But also nitrogen is a limiting factor for plant growth on the salt marsh. Therefor we might expect an interaction between salinity stress and nitrogen availability. Our first hypothesis was that Elymus athericus would be able to make such organic solutes with increasing salt stress. Secondly, nitrogen would have a positive effect on salinity resistance and growth. Third, the plants on the high marsh might have adapted more to salt stress because the populations of Elyrnus are older in the high marsh. To test our hypothesis, I did an experiment with nitrogen fertilisation and salinity manipulation at the high and low marsh on Schiermonnikoog. These plots were treated with different concentrations of salt or fresh water and different concentrations of ammonium sulphate with labelled '5N. Plant growth was measured and soil and plant samples were taken to control the treatment effects. We found no significant differences in plant growth for the different nitrogen treatments. The nitrogen data to control the treatment effects are not yet available, but some results show that some labelled nitrogen did end up in the plants. Differences only occur between habitats, low marsh plants had a bigger shoot length and a higher growth rate. In most cases the salinity treatments did not influence plant performance, because we did not manage to increase or decrease soil salinity with our treatments. The temporal and spatial background variation in soil salinity was very high. However, while the soil salinity in the low marsh is ten times higher than the high marsh, the plant salinity is the same. This indicates the production of organic solutes. It also indicates the adaptation of Elymus to its habitat. Finally, drought also seemed to be an important stress factor during my experiment.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:31
Last Modified: 15 Feb 2018 07:31

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