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Abstract Detail


ANDERSON, ROGER C [1], Anderson, M. Rebecca [1], Bauer, Jonathan T. [2], Loebach, Christopher [3], Slater, Mitchell A. [4].

Extreme climate events affect density of the invasive garlic mustard (Alliaria petiolata) and disrupt years of alternating abundance of first and second year plants.

Garlic mustard, a strict biennial plant in North America, has alternating years of high abundance of 1st-yr and 2nd-yr plants. We monitored changes in abundance of 1st-yr and 2nd-yr plants in permanents plots from 2004 to 2016, and examined years when high abundance of 1st-yr plants was not followed by high abundance of 2nd-yr plants. Second-year plants had high abundance in 2004 and 2006 and 1st-yr plants in 2005 and 2007. However, beginning in 2008 the alternating yearly cycle of abundance was disrupted; 1st-yr plants had high and 2nd-yr plants had low abundances. High abundance of 1st-yr plants in 2008 was most likely due to soil seed bank germination. This unexpected change in abundance of 1st- and 2nd-yr plants could occur with a small proportion of 1st-yr plants in 2007 transitioning to 2nd-yr plants in 2008. Our data showed three times (2007-2008, 2008-2009, and 2013-2014) when years of high abundance of 1st-yr was not followed by a year with high abundance of 2nd-yr plants. Garlic mustard declines have been attributed to reductions of secondary defensive compounds, soil microbial community alteration, and loss of genetic diversity; however, we investigated factors likely to cause sharp declines in expected abundance of 2nd-yr plants in single year. We concluded that Extreme Climate Events (ECE), events deviating from long-term climatic data norms and causing negative organism responses, probably played a role in disrupting alternating abundances of 1st-yr and 2nd-yr plants. We searched long-term climate data (1951-2015) from a nearby (15 km) NOAA weather station, for deviation from monthly and daily norms of temperature and precipitation, and focused on events occurring in the 10th or 90th percentile, and/or two or three standard deviations (SD) from the mean. September 2007 had unusually high temperature and low precipitation, whereas, January 2009, and February and March 2014 had the lowest daily minimum temperature on record. We used Z-scores, SD, percentile, and PCA to test for differences in total precipitation, number of rainy days, contiguous days without precipitation, days with maximum temperatures > 30 C, and mean monthly temperature between 2007 and years 2004-2014 for September. We tested for differences in daily minimum temperature in January 2009, and February and March 2014 separately compared to all other years (2004-2015). Our results indicate ECE’s could be responsible for overall decline in garlic mustard and disruption of annual alternating abundance of 1st-yr and 2nd-yr garlic mustard.

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1 - Illinois State University, School of Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA
2 - Indiana University, Bloomington, IN, 47405, USA
3 - Kapur & Associates Inc, North Port Washington Road, Milwaukee, WI, 53217, USA
4 - USDA Forest Service, Northern Research Station, 1831 Highway 169, Grand Rapids, MN, 55744, USA

invasive species
garlic mustard
extreme climate events.

Presentation Type: Oral Paper
Session: 8, Ecology Section - Invasive Species
Location: Sundance 5/Omni Hotel
Date: Monday, June 26th, 2017
Time: 11:30 AM
Number: 8006
Abstract ID:303
Candidate for Awards:None

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