You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Competitive Effect and Response Rankings in 20 Wetland Plants: Are They Consistent Across Three Environments?
Paul A. Keddy, Lisa Twolan-Strutt and Irene C. Wisheu
Journal of Ecology
Vol. 82, No. 3 (Sep., 1994), pp. 635-643
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/2261270
Page Count: 9
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
1 There is evidence that plants in natural communities form transitive competitive hierarchies, but the pervasiveness and malleability of hierarchies remain controversial. We constructed three competitive rankings among 20 wetland plant species in conditions known to be important in wetlands: a mesic, fertile environment, an infertile environment and a flooded environment. 2 Rankings were constructed using plants grown from seed in pairwise combinations for one growing season in an outdoor compound. The indicator species used to construct the rankings were Carex crinita, Gnaphalium uliginosum and Lycopus americanus. The others represented a wide array of morphologies, habitats and abundances and ranged from the large cosmopolitan Typha angustifolia to the small and rare Sabatia kennedyana. 3 Competitive rankings formed in all three environments. Competitive effect rankings based upon the results for all three indicator species were significantly concordant across the three environments $(W = 0.59; P < 0.05)$, i.e. competitive effect did not change across environment. When calculated separately for each indicator species, rankings across the three environments were significantly concordant for two of the three indicator species. Within any environment the ranking varied among the indicator species. 4 Ranking based upon the mean competitive response to all three phytometer species were not concordant across the three environments $(W = 0.35; P > 0.3)$ and were not concordant when calculated separately for each indicator species. Within any environment, response rankings were significantly concordant for two out of the three indicator species. 5 Competitive effect rankings tended to be constant across environments and were sensitive to the kind of neighbour. Competitive response rankings varied across environments and were insensitive to the kind of neighbour.
Journal of Ecology © 1994 British Ecological Society