Effects of grazing and nitrogen deposition on sand dune systems.
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Katharina Plassmann PhD 2006 - OCR
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Abstract
This study investigated the sand dunes at Newborough Warren, North Wales, UK,
between June 2003 and June 2005. The objective was to understand sand dune ecology under perturbation. Specific aims were to analyse the potential of management by livestock grazing to maintain and restore species-rich, open sand dune plant communities, describe the ecology of the seed bank of dune slacks and examine the potential threat of atmospheric nitrogen deposition to dune grassland vegetation.
Long-term grazing management by domestic livestock had a positive effect on
vegetation communities, especially in dry dune habitats, and is recommended for sand dune conservation management. Plant species diversity increased after the introduction of grazing management, particularly for annual and biennial species, suggesting improved habitat conditions. Exclusion of rabbit and livestock grazing resulted in the increased abundance of tall, competitive graminoids, probably leading to reduced species diversity over longer time periods.
The dune grassland community responded to nitrogen fertilisation with increases in above-ground biomass. Bryophytes showed increased above-ground biomass and tissue nitrogen concentrations. This could lead to community changes in the long term. It is suggested that the critical load for nitrogen for dune grasslands is below the previously proposed 20 kg ha-1 year-1, even for heavily grazed areas. The addition of nitrogen led to enhanced levels of germination from the seed bank in the majority of species. Species affected belonged to early successional communities that are threatened by several factors, including eutrophication.
The dune slacks have diverse seed banks, including species of conservation interest and early successional species with persistent seed banks. Thus, the seed bank has the potential to regenerate earlier successional stages after disturbance. Seedlings of important dune slack species were recorded, increasing the scarce information so far available on these species. Further research is needed into the effects of grazing on seed bank composition.
between June 2003 and June 2005. The objective was to understand sand dune ecology under perturbation. Specific aims were to analyse the potential of management by livestock grazing to maintain and restore species-rich, open sand dune plant communities, describe the ecology of the seed bank of dune slacks and examine the potential threat of atmospheric nitrogen deposition to dune grassland vegetation.
Long-term grazing management by domestic livestock had a positive effect on
vegetation communities, especially in dry dune habitats, and is recommended for sand dune conservation management. Plant species diversity increased after the introduction of grazing management, particularly for annual and biennial species, suggesting improved habitat conditions. Exclusion of rabbit and livestock grazing resulted in the increased abundance of tall, competitive graminoids, probably leading to reduced species diversity over longer time periods.
The dune grassland community responded to nitrogen fertilisation with increases in above-ground biomass. Bryophytes showed increased above-ground biomass and tissue nitrogen concentrations. This could lead to community changes in the long term. It is suggested that the critical load for nitrogen for dune grasslands is below the previously proposed 20 kg ha-1 year-1, even for heavily grazed areas. The addition of nitrogen led to enhanced levels of germination from the seed bank in the majority of species. Species affected belonged to early successional communities that are threatened by several factors, including eutrophication.
The dune slacks have diverse seed banks, including species of conservation interest and early successional species with persistent seed banks. Thus, the seed bank has the potential to regenerate earlier successional stages after disturbance. Seedlings of important dune slack species were recorded, increasing the scarce information so far available on these species. Further research is needed into the effects of grazing on seed bank composition.
Details
| Original language | English |
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| Award date | 2006 |