Abstract
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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Claims 12
Claim · model-written summary
In the field, Benomyl fungicide reduced arbuscular mycorrhizal colonization of Centaurea maculosa roots by more than 80%.
- Taxon
- Centaurea maculosa
Centaurea maculosae0 - Organ / stage
- rootse1
- Treatment
- fungicide (Benomyl)e1
- Interactor
- AM mycorrhizale1symbiont
- Outcome
- AM mycorrhizal colonizatione1
- Direction
- reducede1
- Value
- >80%e1
- Setting
- In the fielde1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e1“In the field, fungicide (Benomyl) reduced AM mycorrhizal colonization of C. maculosa roots by >80%”
Claim · model-written summary
Fungicide did not significantly reduce non-AM fungi.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- Fungicidee2
- Interactor
- non-AM fungie2other
- Outcome
- non-AM fungie2
- Direction
- did not significantly reducee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e2“Fungicide did not significantly reduce non-AM fungi”
Claim · model-written summary
When grown alone, Centaurea maculosa biomass was not affected by fungicide application.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- fungicide applicatione3
- Outcome
- biomasse3
- Direction
- not affectede3
- Qualifier
- When grown alonee3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e3“When grown alone, the biomass of C. maculosa was not affected by the fungicide application”
Claim · model-written summary
Depending on the combination of native competitor and fungicide, Centaurea maculosa biomass varied from 10-fold decreases to 1.9-fold increases.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- native competitor and fungicidee4
- Interactor
- native competitore4other
- Outcome
- biomasse4
- Direction
- variede4
- Value
- 10-fold decreases to 1.9-fold increasese4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e4“depending on the combination of native competitor and fungicide, C. maculosa biomass varied from 10-fold decreases to 1.9-fold increases”
Claim · model-written summary
In untreated soils, Centaurea maculosa grew larger in the presence of Festuca idahoensis or Koeleria cristata than when grown alone.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- presence of Festuca idahoensis or Koeleria cristatae5
- Interactor
- Festuca idahoensis
Festuca idahoensise5other - Second interactor
- Koeleria cristata
.jpg?width=60)
Koeleria pyramidatae5other - Outcome
- grew largere5
- Direction
- largere5
- Qualifier
- In untreated soilse5
- Comparator
- when alonee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e5“In untreated soils, C. maculosa grew larger in the presence of Festuca idahoensis or Koeleria cristata than when alone”
Claim · model-written summary
When fungicide was applied, the positive effects of Festuca and Koeleria on Centaurea maculosa did not occur.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- fungicidee6
- Outcome
- positive effects of Festuca and Koeleria on C. maculosae6
- Direction
- did not occure6
- Comparator
- untreated soilse5
Festuca
KoeleriaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e5“In untreated soils, C. maculosa grew larger in the presence of Festuca idahoensis or Koeleria cristata than when alone”
e6“When fungicide was applied these positive effects of Festuca and Koeleria on C. maculosa did not occur”
Claim · model-written summary
Pseudoroegneria spicata had much stronger competitive effects on Centaurea maculosa than Festuca or Koeleria.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- Pseudoroegneria spicatae7
- Interactor
- Pseudoroegneria spicata
.jpg?width=60)
Pseudoroegneria spicatae7other - Outcome
- competitive effectse7
- Direction
- strongere7
- Comparator
- Festuca or Koeleriae7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e7“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”
Claim · model-written summary
Fungicide reduced the competitive effects of Pseudoroegneria on Centaurea maculosa.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- fungicidee7
- Interactor
- Pseudoroegneria
Pseudoroegneriae7other - Outcome
- competitive effectse7
- Direction
- reducede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e7“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”
Claim · model-written summary
Fungicide increased Centaurea biomass when it competed with the forb Gallardia aristata.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- Fungicidee1
- Interactor
- Gallardia aristatae1other
- Outcome
- Centaurea biomasse1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e1“Fungicide increased Centaurea biomass when competing with the forb Gallardia aristata”
Claim · model-written summary
Fungicide did not affect how the forbs Achillea millefolium and Linum lewisii interacted with Centaurea maculosa.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- fungicidee1
- Interactor
- Achillea millefolium
Achillea millefoliume1other - Second interactor
- Linum lewisii
Linum lewisiie1other - Outcome
- interacted with C. maculosae1
- Direction
- did not affecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e1“However, fungicide did not affect the way two other forbs; Achillea millefolium and Linum lewisii, interacted with C. maculosa”
Claim · model-written summary
Rhizosphere microbial communities of the three native bunchgrass species differed from that of Centaurea maculosa.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Organ / stage
- root zonese1
- Interactor
- microbial communitiese1other
- Outcome
- Rhizosphere microbial communitiese1
- Direction
- differede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e1“Rhizosphere microbial communities in the root zones of the three native bunchgrass species differed from that of C. maculosa”
Claim · model-written summary
Soil biota from different plant rhizospheres did not affect the growth of Centaurea maculosa in the absence of native competitors in greenhouse experiments.
- Taxon
- Centaurea maculosaCentaurea maculosae0
- Treatment
- soil biota from different plant rhizospherese1
- Outcome
- growth of C. maculosae1
- Direction
- did not affecte1
- Qualifier
- in the absence of native competitorse1
- Setting
- greenhouse experimentse1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“invasive weed Centaurea maculosa (spotted knapweed)”
e1“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”