Present address: Atelier Sternen and Partner, Tobeleggweg 19, CH-8049 Zürich, Switzerland.
Contrasting effects of nitrogen, phosphorus and water regime on first- and second-year growth of 16 wetland plant species
Article first published online: 12 DEC 2003
Volume 17, Issue 6, pages 754–765, December 2003
How to Cite
Güsewell, S., Bollens, U., Ryser, P. and Klötzli, F. (2003), Contrasting effects of nitrogen, phosphorus and water regime on first- and second-year growth of 16 wetland plant species. Functional Ecology, 17: 754–765. doi: 10.1111/j.1365-2435.2003.00784.x
- Issue published online: 12 DEC 2003
- Article first published online: 12 DEC 2003
- Received 10 January 2003; revised 5 July 2003; accepted 7 July 2003
- Biomass allocation;
- growth experiment;
- limiting nutrient;
- tissue nutrient concentration;
- water level
- 1The effects of nutrient enrichment on wetland vegetation may depend on the responses of different plant species to nutrient supply over several years, in waterlogged or flooded soils, and under either nitrogen- or phosphorus-limited conditions. However, most growth experiments comparing species from differently productive sites have focused on their short-term responses to variation in N supply. In this study we investigated whether increased N or P supply affects plant growth differently, whether these effects differ between the first and second year of growth, and whether they are modified by the water regime.
- 2Plants of 16 wetland species were grown during two seasons in tubes with sand under full light. Treatments combined three nutrient levels (low N and P, high N, high P) with three water regimes (constantly wet, periodically aerated, periodically flooded).
- 3In the first year, shoot biomass was enhanced by high N supply, particularly in species from nutrient-rich sites; this was associated with reduced shoot P concentration. In the second year, shoot biomass was generally enhanced by high P supply and reduced by high N supply; responses to high P were strongest in species with low shoot biomass and high N concentration but unrelated to the productivity of the species’ sites.
- 4The total biomass produced during both years was smaller at high N supply than at high P supply. A smaller fraction of the N and P supply was recovered in high-N plants, and these plants allocated less biomass to roots than those grown at high P supply or low N and P supply.
- 5Periodic flooding reduced biomass production and nutrient recovery, but hardly influenced the effects of nutrient supply on plant growth. Species from wet meadows were affected more by flooding than species from fens in the first season, but not in the second season.
- 6We propose that high N supply reduced second-year growth because strong P limitation increased below-ground nutrient losses from plants, whereas high P supply enhanced second-year growth by improving N retention in plants. Our results therefore suggest that N and P enrichment may have quite different effects on wetland vegetation.