Species compositional differences on different-aged glacial landscapes drive contrasting responses of tundra to nutrient addition


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dc.contributor.author Hobbie, Sarah E.
dc.contributor.author Gough, Laura
dc.contributor.author Shaver, Gaius R.
dc.date.accessioned 2005-12-28T21:21:44Z
dc.date.available 2005-12-28T21:21:44Z
dc.date.issued 2005-01-17
dc.identifier.uri http://hdl.handle.net/1912/357
dc.description Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Blackwell Publishing for personal use, not for redistribution. The definitive version was published in Journal of Ecology 93 (2005): 770-782, doi:10.1111/j.1365-2745.2005.01006.x.
dc.description.abstract 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, experimental fertilization of moist acidic tussock tundra greatly increased the abundance and productivity of the deciduous dwarf shrub Betula nana. However, this species is largely absent from moist non-acidic tundra. These two common upland tundra community types exhibited markedly different responses to fertilization with nitrogen and phosphorus. In moist acidic tundra, cover of deciduous shrubs (primarily B. nana) increased after only 2 years, and by 4 years vascular biomass and above-ground net primary productivity (ANPP) had increased significantly, almost entirely because of Betula. In moist non-acidic tundra, both biomass and ANPP were again significantly greater, but no single species dominated the response to fertilization. Instead, the effect was due to a combination of several small, sometimes statistically non-significant responses by forbs, graminoids and prostrate deciduous shrubs. The different growth form and species' responses suggest that fertilization will cause carbon cycling through plant biomass to diverge in these two tundra ecosystems. Already, production of new stems by apical growth has increased relative to leaf production in acidic tundra, whereas the opposite has occurred in non-acidic tundra. Secondary stem growth has also increased as a component of primary production in acidic tundra, but is unchanged in non-acidic tundra. Thus, fertilization will probably increase carbon sequestration in woody biomass of B. nana in acidic tundra, while increasing carbon turnover (but not storage) of non-woody species in non-acidic tundra. These results indicate that nutrient enrichment can have very different consequences for plant communities that occur on different geological substrates, because of differences in composition, even though they share the same regional species pool. Although the specific edaphic factors that maintain compositional differences in this case are unknown, variation in soil pH and related variability in soil nutrient availability may well play a role. en
dc.description.sponsorship This research was supported by a collaborative grant from the National Science Foundation (OPP-9902695 to S.E.H. and OPP-9902721 to L.G.) and by the Arctic LTER (DEB-9810222). en
dc.format.extent 77312 bytes
dc.format.extent 993792 bytes
dc.format.mimetype application/msword
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dc.language.iso en_US en
dc.relation.uri http://dx.doi.org/10.1111/j.1365-2745.2005.01006.x
dc.subject Alaska en
dc.subject Arctic en
dc.subject Betula nana en
dc.subject Fertilization en
dc.subject Moist acidic tundra en
dc.subject Moist non-acidic tundra en
dc.subject Net primary production en
dc.subject Nitrogen en
dc.subject pH en
dc.subject Phosphorus en
dc.title Species compositional differences on different-aged glacial landscapes drive contrasting responses of tundra to nutrient addition en
dc.type Preprint en

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