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Plant functional types do not predict biomass responses to removal and fertilization in Alaskan tussock tundra
Article first published online: 15 APR 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Journal of Ecology
Volume 96, Issue 4, pages 713–726, July 2008
How to Cite
Bret-Harte, M. S., Mack, M. C., Goldsmith, G. R., Sloan, D. B., DeMarco, J., Shaver, G. R., Ray, P. M., Biesinger, Z. and Chapin, F. S. (2008), Plant functional types do not predict biomass responses to removal and fertilization in Alaskan tussock tundra. Journal of Ecology, 96: 713–726. doi: 10.1111/j.1365-2745.2008.01378.x
- Issue published online: 10 JUN 2008
- Article first published online: 15 APR 2008
- Received 1 November 2007; accepted 7 March 2008; Handling Editor: Richard Bardgett
- arctic tundra;
- biomass compensation;
- plant functional types;
- species interactions;
- species removal;
- soil nutrient availability
- 1Plant communities in natural ecosystems are changing and species are being lost due to anthropogenic impacts including global warming and increasing nitrogen (N) deposition. We removed dominant species, combinations of species and entire functional types from Alaskan tussock tundra, in the presence and absence of fertilization, to examine the effects of non-random species loss on plant interactions and ecosystem functioning.
- 2After 6 years, growth of remaining species had compensated for biomass loss due to removal in all treatments except the combined removal of moss, Betula nana and Ledum palustre (MBL), which removed the most biomass. Total vascular plant production returned to control levels in all removal treatments, including MBL. Inorganic soil nutrient availability, as indexed by resins, returned to control levels in all unfertilized removal treatments, except MBL.
- 3Although biomass compensation occurred, the species that provided most of the compensating biomass in any given treatment were not from the same functional type (growth form) as the removed species. This provides empirical evidence that functional types based on effect traits are not the same as functional types based on response to perturbation. Calculations based on redistributing N from the removed species to the remaining species suggested that dominant species from other functional types contributed most of the compensatory biomass.
- 4Fertilization did not increase total plant community biomass, because increases in graminoid and deciduous shrub biomass were offset by decreases in evergreen shrub, moss and lichen biomass. Fertilization greatly increased inorganic soil nutrient availability.
- 5In fertilized removal treatments, deciduous shrubs and graminoids grew more than expected based on their performance in the fertilized intact community, while evergreen shrubs, mosses and lichens all grew less than expected. Deciduous shrubs performed better than graminoids when B. nana was present, but not when it had been removed.
- 6Synthesis. Terrestrial ecosystem response to warmer temperatures and greater nutrient availability in the Arctic may result in vegetative stable-states dominated by either deciduous shrubs or graminoids. The current relative abundance of these dominant growth forms may serve as a predictor for future vegetation composition.