Invader disruption of belowground plant mutualisms reduces carbon acquisition and alters allocation patterns in a native forest herb.
Invasive plants impose novel selection pressures on naïve mutualistic interactions between native plants and their partners. As most plants critically rely on root fungal symbionts (RFSs) for soil resources, invaders that disrupt plant-RFS mutualisms can significantly depress native plant fitness. Here, we investigate the consequences of RFS mutualism disruption on native plant fitness in a glasshouse experiment with a forest invader that produces known anti-fungal allelochemicals. Over 5 months, we regularly applied either green leaves of the allelopathic invader Alliaria petiolata, a nonsystemic fungicide to simulate A. petiolata's effects, or green leaves of nonallelopathic Hesperis matronalis (control) to pots containing the native Maianthemum racemosum and its RFSs. We repeatedly measured M. racemosum physiology and harvested plants periodically to assess carbon allocation. Alliaria petiolata and fungicide treatment effects were indistinguishable: we observed inhibition of the RFS soil hyphal network and significant reductions in M. racemosum physiology (photosynthesis, transpiration and conductance) and allocation (carbon storage, root biomass and asexual reproduction) in both treatments relative to the control. Our findings suggest a general mechanistic hypothesis for local extinction of native species in ecosystems challenged by allelopathic invaders: RFS mutualism disruption drives carbon stress, subsequent declines in native plant vigor, and, if chronic, declines in RFS-dependent species abundance.
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
Alison N
http://orcid.org/0000-0003-3495-3371
AN
Hale
Département de Biologie, Université Laval, Québec, QC, G1V 0A6, Canada.
Line
L
Lapointe
Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260, USA.|Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, 37996, USA.
Susan
S
Kalisz
D064089:Allelopathy; D019607:Brassicaceae / Q000187:drug effects / Q000502:physiology*; D002244:Carbon / Q000378:metabolism*; D017753:Ecosystem; D065928:Forests; D058865:Introduced Species; D019668:Liliaceae / Q000502:physiology*; D010675:Pheromones / Q000494:pharmacology; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology; D018517:Plant Roots / Q000382:microbiology; D027343:Rhizome / Q000378:metabolism; D012988:Soil Microbiology; D013559:Symbiosis
D010675:Pheromones; D002244:Carbon
Alliaria petiolata; allelopathy; carbon allocation; invasion; mutualism disruption; physiology; root fungal symbionts