Effects of nutrient addition and acidification on plant species diversity and seed germination in heathland
Article first published online: 11 DEC 2002
Journal of Applied Ecology
Volume 39, Issue 6, pages 937–948, December 2002
How to Cite
Roem, W. J., Klees, H. and Berendse, F. (2002), Effects of nutrient addition and acidification on plant species diversity and seed germination in heathland. Journal of Applied Ecology, 39: 937–948. doi: 10.1046/j.1365-2664.2002.00768.x
- Issue published online: 11 DEC 2002
- Article first published online: 11 DEC 2002
- Received 16 May 2001; final copy received 4 July 2002
- nitrogen availability;
- N:P ratio;
- phosphorus availability;
- species richness
- 1The atmospheric deposition of sulphur and nitrogen compounds in the Netherlands has been responsible for decreasing plant species diversity in heathland. To unravel the relative importance of nitrogen compounds on soil acidification and eutrophication, and hence on the vegetation, we carried out a factorial addition experiment and a germination experiment in heathland on nutrient-poor sandy soil.
- 2We changed nutrient availability and acidity independently in eight different treatments that, respectively, added nutrients or carbon in various combinations (N, P, glucose) or added acidifying or neutralizing compounds. One treatment also involved adding Al. Additions occurred five times per year during 5 years, in an area from which sods had been removed before the experiment began. The same design was used for the germination experiment, but the treatments were applied for 2 years.
- 3Our results showed that acidification was the most important factor in reducing species diversity. In addition, the germination of several heathland species was significantly reduced in plots with a pH below 5, and germination was very poor in plots where Al had been added.
- 4The number of plant species declined particularly with increasing Al in the upper soil horizons. We conclude that this relationship is responsible for the influence of acidification on plant species richness in heathland.
- 5The influence of nutrient availability on species composition in heathland was subsidiary to acidity, but nutrient availability influenced species composition in an independent way. The growth of the three dominant species (Molinia caerulea, Calluna vulgaris and Erica tetralix) was limited by different nutrients. Erica tetralix was limited by N, Calluna vulgaris by P and Molinia caerulea by both N and P. We argue that increased N availability will change the relative availability of N and P, which can decrease species diversity.
- 6Together these results show how factorial experiments can elucidate the complex ecological effects arising from sulphur and nitrogen deposition, revealing different mechanisms that change species richness and community composition.