Plant functional types do not predict biomass responses to removal and fertilization in Alaskan tussock tundra
Bret-Harte, M. Syndonia
Mack, Michelle C.
Goldsmith, Gregory R.
Sloan, Daniel B.
Shaver, Gaius R.
Ray, Peter M.
Chapin, F. Stuart
MetadataShow full item record
KeywordArctic tundra; Biodiversity; Biomass compensation; Nitrogen; Plant functional types; Productivity; Species interactions; Species removal; Soil nutrient availability
Plant 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. After 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. Although 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. Fertilization 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. In 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. Synthesis. 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.
© 2008 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution License 2.5. The definitive version was published in Journal of Ecology 96 (2008): 713-726, doi:10.1111/j.1365-2745.2008.01378.x.
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by-nc/2.5/
Showing items related by title, author, creator and subject.
Home site advantage in two long-lived arctic plant species : results from two 30-year reciprocal transplant studies Bennington, Cynthia C.; Fetcher, Ned; Vavrek, Milan C.; Shaver, Gaius R.; Cummings, Kelli J.; McGraw, James B. (2012-03-30)Reciprocal transplant experiments designed to quantify genetic and environmental effects on phenotype are powerful tools for the study of local adaptation. For long-lived species, especially those in habitats with short ...
Species compositional differences on different-aged glacial landscapes drive contrasting responses of tundra to nutrient addition Hobbie, Sarah E.; Gough, Laura; Shaver, Gaius R. (2005-01-17)In the northern foothills of the Brooks Range, Alaska, moist non-acidic tundra dominates more recently deglaciated upland landscapes, whereas moist acidic tundra dominates older upland landscapes. In previous studies, ...
Hobbie, John E.; Hobbie, Erik A. (Ecological Society of America, 2006-04)When soil nitrogen is in short supply, most terrestrial plants form symbioses with fungi (mycorrhizae): hyphae take up soil nitrogen, transport it into plant roots, and receive plant sugars in return. In ecosystems, the ...