Record ID No. |
165 |
Author(s) |
Callaway R.M., Thelen G. C., Barth S., Ramsey P. W., Gannon J. E. , 2004 |
Affiliation |
University of Montana, Division of Biological Science, Missoula, MT 59812 |
Title |
Soil fungi alter interactions between the invader Centaurea maculosa and North American natives |
Source. Vol.(no):Page |
Ecology. Proceedings. 85(4): 1062-1071p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Soil plant relations |
Sub-subjects |
Fungicides |
Host |
Centaurea maculosa, Festuca idahoensis, Koeleria cristata, Pseudoroegneria spicata, Gallardia aristata, Achillea millefolium, Linum lewisii, Bunch grass |
Organism |
n.a. |
Country |
Montana, North America |
Abstracts |
Soil microbes may affect the way exotic invasive plants
interact with native neighbors. We investigated the effects of
soil fungi on interactions between the invasive weed Centaurea
maculosa (spotted knapweed) and six species native to the
intermountain prairies of the northwestern United States. We
also compared the effect of C. maculosa on the composition of
the soil microbial community to that of the native species. In
the field, fungicide (Benomyl) reduced AM mycorrhizal
colonization of C. maculosa roots by >80%. Fungicide did not
significantly reduce non-AM fungi. When grown alone, the biomass
of C. maculosa was not affected by the fungicide application.
However, depending on the combination of native competitor and
fungicide, C. maculosa biomass varied from 10-fold decreases to
1.9-fold increases. In untreated soils, C. maculosa grew larger
in the presence of Festuca idahoensis or Koeleria cristata than
when alone. When fungicide was applied these positive effects of
Festuca and Koeleria on C. maculosa did not occur. A third
native grass, Pseudoroegneria spicata, had much stronger
competitive effects on C. maculosa than Festuca or Koeleria, and
fungicide reduced the competitive effects of Pseudoroegneria.
Fungicide increased Centaurea biomass when competing with the
forb Gallardia aristata. However, fungicide did not affect the
way two other forbs; Achillea millefolium and Linum lewisii,
interacted with C. maculosa. Rhizosphere microbial communities
in the root zones of the three native bunchgrass species
differed from that of C. maculosa. However, despite the strong
effects of soil fungi in field interactions and differences in
microbial community composition, soil biota from different plant
rhizospheres did not affect the growth of C. maculosa in the
absence of native competitors in greenhouse experiments. Our
results suggest that successful invasions by exotic plant
species can be affected by complex and often beneficial effects
of local soil microbial communities. These effects were not
manifest as simple direct effects, but become apparent only when
native plants, invasive plants, and soil microbial communities
were interacting at the same time
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