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Abstract Detail

Conservation Biology

Kupisz, Nichole [1], Greer, Gary K. [2].

Comparison of understory biodiversity between Ailanthus altissima versus native tree canopies in two disparate forests.

Ailanthus altissima is an invasive tree in the United States, currently reported in 43 of the lower 48 states. Native to China, it exudes well documented allelopathic compounds from its roots that can impact the germination and growth of neighboring seeds and plants. The purpose of the current study was to compare understory floral biodiversity beneath A. altissima versus native tree canopies in two disparate locations to determine if a signature of allelopathic effects as detectable. The first study was conducted at Kanawha State Forest (KSF), West Virginia in 2003. The KSF study examined the understories of 30 A. altissima trees with diameters greater than 10cm dbh from throughout the forest. Each A. altissima was paired with the nearest native tree that was at a minimum distance of 10m from the target A. altissima and possessed a dbh of at least 10cm, hence the species identity of the native tree varied. The second study was conducted at Yankee springs Recreational Area (YSRA) in Barry county, Michigan from 2009-2012. Methods for the YSRA study were nearly identical to the KSF study, however, the understories of 20 A. altissima-native tree pairings were studied and the identity of the trees surveyed varied from year to year. Understory biodiversity was assessed using species area curves (SAC's), species richness, Shannon's evenness and Simpson's diversity indices. Results from the SAC's consistently show that the A. altissima understories possessed a greater frequency of uncommon species and hence greater species richness compared to the native tree understories. Likewise, both Shannon's and Simpson's diversity indices were consistently higher for Ailanthus than native plots indicating greater diversity and evenness in understories beneath A. altissima; however, the strength of these differences varied by year from significant to non-significant at a critical value of p < 0.05. Understories beneath A. altissima also tended to have higher invasive species richness, a pattern consistent with the invasion meltdown hypothesis. Given the close proximity of each A. altissima x native tree pair, our results are consistent with the hypothesis that differences in diversity were an outcome of allelopathic repression of understory competition by A. altissima. Our findings suggest A. altissima has the potential to alter community structure by allelopathically facilitating the persistence of competitively inferior species and the establishment of invasive species and that the strength of the effect may vary among years due to climatic variation.

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1 - Grand Valley State University, 141 Manzana Ct NW, #3a, Grand Rapids, MI, 49534, USA
2 - Grand Valley State University, Biology, 1 Campus Drive, Allendale, MI, 49401-1000, USA

Ailanthus altissima
Kanawha State Forest
Yankee Springs Recreational Area

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PCB005
Abstract ID:566
Candidate for Awards:None

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