Record ID No. |
167 |
Author(s) |
Carey E. V., Marler M. J., Callaway R. M. , 2004 |
Affiliation |
University of Minnesota, Department of Forest Resources, 115 Green Hall,1530 Cleveland Ave N, St Paul, MN 55108 |
Title |
Mycorrhizae transfer carbon from a native grass to an invasive weed: evidence from stable isotopes and physiology |
Source. Vol.(no):Page |
Plant Ecology. 172(1): 133-141p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Soil plant relations |
Sub-subjects |
Nutrition |
Host |
Weeds, Exotics, Spotted knapweed, Cantaurea maculosa, Grasses, Festuca idahoensis, Bunch grass, Boutoloua gracilis, Blue gramma |
Organism |
n.a. |
Country |
U.S.A., North America |
Abstracts |
Invasive exotic weeds pose one of the earth's most
pressing environmental problems. Although many invaders
completely eliminate native plant species from some communities,
ecologists know little about the mechanisms by which these
exotics competitively exclude other species. Mycorrhizal fungi
radically alter competitive interactions between plants within
natural communities, and a recent study has shown that
arbuscular mycorrhizal (AM) fungi provide a substantial
competitive advantage to spotted knapweed, Centaurea maculosa, a
noxious perennial plant that has spread throughout much of the
native prairie in the northwestern U. S. Here we present
evidence that this advantage is potentially due to mycorrhizally
mediated transfer of carbon from a native bunch-grass, Festuca
idahoensis, to Centaurea. Centaurea maculosa, Festuca idahoensis
(Idaho fescue, C-3), and Bouteloua gracilis (blue gramma, C-4)
were grown in the greenhouse either alone or with Centaurea in
an incomplete factorial design with and without AM fungi.
Centaurea biomass was 87-168% greater in all treatments when
mycorrhizae were present in the soil (P < 0.0001). However,
Centaurea biomass was significantly higher in the treatment with
both mycorrhizae and Festuca present together than in any other
treatment combination (P < 0.0001). This high biomass was
attained even though Centaurea photosynthetic rates were 14%
lower when grown with Festuca and mycorrhizae together than when
grown with Festuca without mycorrhizae. Neither biomass nor
photosynthetic rates of Centaurea were affected by competition
with the C-4 grass Bouteloua either with or without mycorrhizae.
The stable isotope signature of Centaurea leaves grown with
Festuca and mycorrhizae was more similar to that of Festuca,
than when Centaurea was grown alone with mycorrhizae (P = 0.06),
or with Festuca but without mycorrhizae (P = 0.09). This
suggests that carbon was transferred from Festuca to the
invasive weed. We estimated that carbon transferred from Festuca
by mycorrhizae contributed up to 15% of the aboveground carbon
in Centaurea plants. Our results indicate that carbon parasitism
via AM soil fungi may be an important mechanism by which
invasive plants out compete their neighbors, but that this
interaction is highly species-specific.
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