Disrupting mycorrhizal mutualisms

A potential mechanism by which exotic tamarisk outcompetes native cottonwoods

Kelley A. Meinhardt, Catherine A Gehring

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasives can negatively impact native species, yet our understanding of this mechanism's role in exotic species invasion is still in its infancy. Here, we provide several lines of evidence indicating that invasive tamarisk (Tamarix sp.) negatively affects native cottonwoods (Populus fremontii) by disrupting their associations with arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. At a field site in the early stages of tamarisk invasion, cottonwoods with tamarisk neighbors had reduced EM colonization and altered EM fungal community composition relative to cottonwoods with native neighbors, leading to reductions in EM propagule abundance in the soil beneath tamarisk. Similarly, AM colonization of cottonwoods was reduced with a tamarisk neighbor, but there were no significant changes in AM fungal spore communities or propagule abundance. Root colonization by nonmycorrhizal fungi, including potential pathogens, was higher in cottonwoods with tamarisk neighbors. A greenhouse experiment in which AM and EM inoculation and plant neighbor were manipulated in a fully factorial design showed that cottonwoods benefited from mycorrhizas, especially EM, in terms of shoot biomass when grown with a conspecific, but shoot biomass was similar to that of nonmycorrhizal controls when cottonwoods were grown with a tamarisk neighbor. These results are partially explained by a reduction in EM but not AM colonization of cottonwoods by a tamarisk neighbor. Tamarisk neighbors negatively affected cottonwood specific leaf area, but not chlorophyll content, in the field. To pinpoint a mechanism for these changes, we measured soil chemistry in the field and the growth response of an EM fungus (Hebeloma crustuliniforme) to saltamended media in the laboratory. Tamarisk increased both NO 3 - concentrations and electrical conductivity 2.5-fold beneath neighboring cottonwoods in the field. Salt-amended media did not affect the growth of H. crustuliniforme. Our findings demonstrate that a nonnative species, even in the early stages of invasion, can negatively affect a native species by disrupting its mycorrhizal symbioses. Some of these changes in mycorrhizal fungal communities may remain as legacy effects of invasives, even after their removal, and should be considered in management and restoration efforts.

Original languageEnglish (US)
Pages (from-to)532-549
Number of pages18
JournalEcological Applications
Volume22
Issue number2
DOIs
StatePublished - Mar 2012

Fingerprint

propagule
colonization
fungus
native species
shoot
plant and fungus
root colonization
soil chemistry
biomass
symbiosis
growth response
leaf area
inoculation
electrical conductivity
community composition
spore
chlorophyll
pathogen
fold
salt

Keywords

  • AM and EM colonization
  • Cottonwood
  • Exotic species
  • Hebeloma crustuliniforme
  • Invasive species
  • Mutualism disruption
  • Mycorrhizal fungi
  • Native
  • Populus fremontii
  • Tamarisk
  • Tamarix sp

ASJC Scopus subject areas

  • Ecology

Cite this

Disrupting mycorrhizal mutualisms : A potential mechanism by which exotic tamarisk outcompetes native cottonwoods. / Meinhardt, Kelley A.; Gehring, Catherine A.

In: Ecological Applications, Vol. 22, No. 2, 03.2012, p. 532-549.

Research output: Contribution to journalArticle

@article{8182510e198842fbbbacc39a3ad979e8,
title = "Disrupting mycorrhizal mutualisms: A potential mechanism by which exotic tamarisk outcompetes native cottonwoods",
abstract = "The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasives can negatively impact native species, yet our understanding of this mechanism's role in exotic species invasion is still in its infancy. Here, we provide several lines of evidence indicating that invasive tamarisk (Tamarix sp.) negatively affects native cottonwoods (Populus fremontii) by disrupting their associations with arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. At a field site in the early stages of tamarisk invasion, cottonwoods with tamarisk neighbors had reduced EM colonization and altered EM fungal community composition relative to cottonwoods with native neighbors, leading to reductions in EM propagule abundance in the soil beneath tamarisk. Similarly, AM colonization of cottonwoods was reduced with a tamarisk neighbor, but there were no significant changes in AM fungal spore communities or propagule abundance. Root colonization by nonmycorrhizal fungi, including potential pathogens, was higher in cottonwoods with tamarisk neighbors. A greenhouse experiment in which AM and EM inoculation and plant neighbor were manipulated in a fully factorial design showed that cottonwoods benefited from mycorrhizas, especially EM, in terms of shoot biomass when grown with a conspecific, but shoot biomass was similar to that of nonmycorrhizal controls when cottonwoods were grown with a tamarisk neighbor. These results are partially explained by a reduction in EM but not AM colonization of cottonwoods by a tamarisk neighbor. Tamarisk neighbors negatively affected cottonwood specific leaf area, but not chlorophyll content, in the field. To pinpoint a mechanism for these changes, we measured soil chemistry in the field and the growth response of an EM fungus (Hebeloma crustuliniforme) to saltamended media in the laboratory. Tamarisk increased both NO 3 - concentrations and electrical conductivity 2.5-fold beneath neighboring cottonwoods in the field. Salt-amended media did not affect the growth of H. crustuliniforme. Our findings demonstrate that a nonnative species, even in the early stages of invasion, can negatively affect a native species by disrupting its mycorrhizal symbioses. Some of these changes in mycorrhizal fungal communities may remain as legacy effects of invasives, even after their removal, and should be considered in management and restoration efforts.",
keywords = "AM and EM colonization, Cottonwood, Exotic species, Hebeloma crustuliniforme, Invasive species, Mutualism disruption, Mycorrhizal fungi, Native, Populus fremontii, Tamarisk, Tamarix sp",
author = "Meinhardt, {Kelley A.} and Gehring, {Catherine A}",
year = "2012",
month = "3",
doi = "10.1890/11-1247.1",
language = "English (US)",
volume = "22",
pages = "532--549",
journal = "Ecological Appplications",
issn = "1051-0761",
publisher = "Ecological Society of America",
number = "2",

}

TY - JOUR

T1 - Disrupting mycorrhizal mutualisms

T2 - A potential mechanism by which exotic tamarisk outcompetes native cottonwoods

AU - Meinhardt, Kelley A.

AU - Gehring, Catherine A

PY - 2012/3

Y1 - 2012/3

N2 - The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasives can negatively impact native species, yet our understanding of this mechanism's role in exotic species invasion is still in its infancy. Here, we provide several lines of evidence indicating that invasive tamarisk (Tamarix sp.) negatively affects native cottonwoods (Populus fremontii) by disrupting their associations with arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. At a field site in the early stages of tamarisk invasion, cottonwoods with tamarisk neighbors had reduced EM colonization and altered EM fungal community composition relative to cottonwoods with native neighbors, leading to reductions in EM propagule abundance in the soil beneath tamarisk. Similarly, AM colonization of cottonwoods was reduced with a tamarisk neighbor, but there were no significant changes in AM fungal spore communities or propagule abundance. Root colonization by nonmycorrhizal fungi, including potential pathogens, was higher in cottonwoods with tamarisk neighbors. A greenhouse experiment in which AM and EM inoculation and plant neighbor were manipulated in a fully factorial design showed that cottonwoods benefited from mycorrhizas, especially EM, in terms of shoot biomass when grown with a conspecific, but shoot biomass was similar to that of nonmycorrhizal controls when cottonwoods were grown with a tamarisk neighbor. These results are partially explained by a reduction in EM but not AM colonization of cottonwoods by a tamarisk neighbor. Tamarisk neighbors negatively affected cottonwood specific leaf area, but not chlorophyll content, in the field. To pinpoint a mechanism for these changes, we measured soil chemistry in the field and the growth response of an EM fungus (Hebeloma crustuliniforme) to saltamended media in the laboratory. Tamarisk increased both NO 3 - concentrations and electrical conductivity 2.5-fold beneath neighboring cottonwoods in the field. Salt-amended media did not affect the growth of H. crustuliniforme. Our findings demonstrate that a nonnative species, even in the early stages of invasion, can negatively affect a native species by disrupting its mycorrhizal symbioses. Some of these changes in mycorrhizal fungal communities may remain as legacy effects of invasives, even after their removal, and should be considered in management and restoration efforts.

AB - The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasives can negatively impact native species, yet our understanding of this mechanism's role in exotic species invasion is still in its infancy. Here, we provide several lines of evidence indicating that invasive tamarisk (Tamarix sp.) negatively affects native cottonwoods (Populus fremontii) by disrupting their associations with arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. At a field site in the early stages of tamarisk invasion, cottonwoods with tamarisk neighbors had reduced EM colonization and altered EM fungal community composition relative to cottonwoods with native neighbors, leading to reductions in EM propagule abundance in the soil beneath tamarisk. Similarly, AM colonization of cottonwoods was reduced with a tamarisk neighbor, but there were no significant changes in AM fungal spore communities or propagule abundance. Root colonization by nonmycorrhizal fungi, including potential pathogens, was higher in cottonwoods with tamarisk neighbors. A greenhouse experiment in which AM and EM inoculation and plant neighbor were manipulated in a fully factorial design showed that cottonwoods benefited from mycorrhizas, especially EM, in terms of shoot biomass when grown with a conspecific, but shoot biomass was similar to that of nonmycorrhizal controls when cottonwoods were grown with a tamarisk neighbor. These results are partially explained by a reduction in EM but not AM colonization of cottonwoods by a tamarisk neighbor. Tamarisk neighbors negatively affected cottonwood specific leaf area, but not chlorophyll content, in the field. To pinpoint a mechanism for these changes, we measured soil chemistry in the field and the growth response of an EM fungus (Hebeloma crustuliniforme) to saltamended media in the laboratory. Tamarisk increased both NO 3 - concentrations and electrical conductivity 2.5-fold beneath neighboring cottonwoods in the field. Salt-amended media did not affect the growth of H. crustuliniforme. Our findings demonstrate that a nonnative species, even in the early stages of invasion, can negatively affect a native species by disrupting its mycorrhizal symbioses. Some of these changes in mycorrhizal fungal communities may remain as legacy effects of invasives, even after their removal, and should be considered in management and restoration efforts.

KW - AM and EM colonization

KW - Cottonwood

KW - Exotic species

KW - Hebeloma crustuliniforme

KW - Invasive species

KW - Mutualism disruption

KW - Mycorrhizal fungi

KW - Native

KW - Populus fremontii

KW - Tamarisk

KW - Tamarix sp

UR - http://www.scopus.com/inward/record.url?scp=84859521577&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84859521577&partnerID=8YFLogxK

U2 - 10.1890/11-1247.1

DO - 10.1890/11-1247.1

M3 - Article

VL - 22

SP - 532

EP - 549

JO - Ecological Appplications

JF - Ecological Appplications

SN - 1051-0761

IS - 2

ER -