Species compositional differences on different-aged glacial landscapes drive contrasting responses of tundra to nutrient addition
MetadataShow full item record
KeywordAlaska; Arctic; Betula nana; Fertilization; Moist acidic tundra; Moist non-acidic tundra; Net primary production; Nitrogen; pH; Phosphorus
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.
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.
Showing items related by title, author, creator and subject.
Parazoo, N. C.; Denning, A. S.; Berry, J. A.; Wolf, Aaron S.; Randall, D. A.; Kawa, S. Randolph; Pauluis, O.; Doney, Scott C. (American Geophysical Union, 2011-05-12)Atmospheric mixing ratios of CO2 are strongly seasonal in the Arctic due to mid-latitude transport. Here we analyze the seasonal influence of moist synoptic storms by diagnosing CO2 transport from a global model on moist ...
Malkus, Joanne Starr (Woods Hole Oceanographic Institution, 1957-01)Comparison of the lower trade-wind air under conditions of strong versus weak circulation is continued, Moisture and thermal structure and transports from the top of the mixed layer up to the trade-wind inversion are ...
Malkus, Joanne Starr (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1958-08)The trade-wind moist layer is itself subdivided in the vertical into two superposed layers of different convective regime, because of the occurrence of water vapor condensation at about 600-700 m above the tropical oceans. ...