Role of species identity in plant invasions: experimental test using Imperata cylindrica |
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Authors: | Pedram Daneshgar Shibu Jose |
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Institution: | (1) Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames , IA, USA;(2) School of Forest Resources and Conservation, University of Florida, 351 Newins-Ziegler Hall, P.O. Box 110410, Gainesville, FL 32611, USA |
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Abstract: | The role of species richness, functional diversity and species identity of native Florida sandhill understory species were
tested with Imperata cylindrica, an exotic rhizomatous grass, in mesocosms. I. cylindrica was introduced 1 year after the following treatments were established: a control with no native species, five monocultures,
a grass mix treatment, a forb mix treatment, and a 3-species treatment and a 5-species treatment. Monthly cover, final biomass,
root length, root length density (RLD) and specific root length (SRL) of all species were determined for one full growing
season. There was a significant negative linear relationship between the cover of native species and I. cylindrica (r
2 = 0.59, P = 0.01) and a negative logarithmic relationship between the biomass of native species and I. cylindrica (r
2 = 0.70, P = 0.003). There was no diversity–invasibility relationship. Grasses proved to be the most resistant functional group providing
resistance alone and in mixed functional communities. Repeated measures analysis demonstrated that treatments including Andropogon virginicus were the most resistant to invasion over time (P < 0.001). Significantly greater root length (P = 0.002), RLD (P = 0.011) and SRL (P < 0.001) than all of the native species and I. cylindrica in monocultures and in mixed communities made A. virginicus successful. The root morphology characteristics allowed it to be a great competitor belowground where I. cylindrica was most aggressive. The results suggest that species identity could be more important than species or functional richness
in determining community resistance to invasion. |
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Keywords: | Elton’ s hypothesis Community resistance Exotic invasion Andropogon virginicus Belowground biomass Root length density |
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