Abstract Detail

Ecological Section

Workman, Rachael [1], Cruzan, Mitchell [2].

Performance and competition of invasive grass Brachypodium sylvaticum differentially impacted by arbuscular mycorrhizal fungi from adjacent invaded and noninvaded ranges.

Understanding how biotic interactions may impact invasion dynamics is essential for predicting invasive plant success. Plant-plant competition and symbiotic interactions have been hypothesized to facilitate or hinder invasive plant establishment and spread. Competition can prevent range expansion or establishment of an invasive monoculture, while soil fungal mutualisms have the potential to impact invasion along a continuum ranging from facilitation to deterrence. Mycelial networks formed by these soil fungi can connect competing hosts and thus impact the competitive success of invasive plants, but the direction and extent of this impact is a subject of controversy in invasion ecology. This study evaluated the performance and competitive responses of the newly invasive grass Brachypodium sylvaticum to conspecifics and to the native grass Bromus carinatus grown in sterile or live soil. The “live soil” contained host-associated AMF inoculum collected from the rhizosphere of either the invasive in an invaded range or native in an adjacent noninvaded range. Interestingly, all plant pairings exhibited decreased performance when grown in invaded range soil, and there was a negative correlation between mycorrhizal colonization and plant growth (in tiller number, shoot dry mass and chlorophyll). A positive effect of neighbor size on plant growth (a proxy for competitive effect) was found, but only in those plants grown in live soil, when AMF (and other organisms) were present. Future experiments will determine if this effect is due to the formation of a common mycelial network, and if results are replicable with plants grown in soil sampled from multiple ranges.

Broader Impacts:

1 - Portland State University, Biology, 1719 SW 10th Ave, SRTC Rm. 246, Portland, OR, 97210, USA
2 - Portland State University, Department of Biology, PO BOX 751, PORTLAND, OR, 97207, USA

Keywords:
invasion
competition
arbuscular mycorrhizal fungi (AMF)
Brachypodium sylvaticum.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:45 PM
Number: PEC011
Abstract ID:338
Candidate for Awards:Ecological Section Best Graduate Student Poster