Source: UNIVERSITY OF ILLINOIS submitted to
GENETIC VARIATION IN ALLELOCHEMISTRY OF GARLIC MUSTARD (ALLIARIA PETIOLATA): ITS ROLE IN DEMOGRAPHY AND IMPLICATIONS FOR MANAGEMENT
 
PROJECT DIRECTOR: Lankau, R.
 
PERFORMING ORGANIZATION
NATURAL HISTORY
UNIVERSITY OF ILLINOIS
URBANA,IL 61801
 
NON TECHNICAL SUMMARY: Garlic mustard is one of the most problematic invaders of North American forests. The European species has spread to 36 states, where it can form dense stands, displacing native understory plants and tree seedlings. Garlic mustard's success as an invader may be due in part to its production of toxic chemicals, which inhibit the growth of native plants and the soil microbes which many native plants need to grow properly. While it is known that many invasive species produce toxic chemicals, further research is needed to develop improved control and restoration practices that utilize this knowledge effectively. In this project, I will determine whether the amount of toxic chemicals produced by garlic mustard differs from place to place, due to differences in the sites or the genetics of the garlic mustard population. I will also develop cost-effective ways to measure the amount of toxic chemicals produced at a given site. Secondly, I will determine how these differences in chemistry among sites affect the rate of spread of the species. Finally, I will compare the efficacy of garlic mustard removal and efforts to restore native plants in sites with produce high or low levels of the toxic chemicals. I will use these results to develop guidelines that managers can use to assign restoration priorities to their specific populations. This research will increase our basic knowledge of species invasions while also providing information directly applicable to managers attempting to control the spread of garlic mustard and restore invaded areas.
 
OBJECTIVES: For knowledge of allelopathy (the ability of a plant species to inhibit other organisms through the production of toxic chemicals) to result in improved control of invasive species and restoration of invaded habitats, research must extend beyond simply demonstrating the existence of allelopathy to investigate: 1) Quantitative variation in allelopathy across an invasion front; 2) The effects of allelopathy on population dynamics of the invader; and 3) Whether data on site-level variation in allelopathic activity can target and improve the success of management and restoration efforts. To these ends, this project will address four major objectives: Objective 1. Quantify variation in soil quality and allelopathic potential within and among A. petiolata populations, and determine cost-effective assays of allelopathic activity. I hypothesize that sites with extensive, dense, and old A. petiolata populations will have lower allelopathic activities than those with young, small, and/or sparse populations, and that allelopathic activity will correlate strongly with glucosinolate concentrations, although soil quality may reflect past allelopathic activities more than current ones. Objective 2. Determine how variation in allelopathy affects population growth and demography. I hypothesize that rates of population growth and spatial spread will be positively correlated with allelopathic activity and glucosinolate concentration and that allelopathic activity will primarily affect the seedling to rosette transition, when plant competition is strongest. Objective 3. Compare the efficacy of alternative restoration and management practices in A. petiolata populations with high or low allelochemical concentrations. I hypothesize that native soil and plant restoration will be more effective in populations with lower allelochemical concentrations, due to greater survival of soil inoculums. However, in highly allelopathic populations, A. petiolata removal will be necessary (perhaps for several years) before native plant and soil restoration will be successful. Objective 4. Develop guidelines for prioritizing control and restoration efforts based on allelopathic activities and/or glucosinolate concentrations of specific populations. Specific ranges of glucosinolate concentration will be identified in which restoration efforts have a high or low probability of success
 
APPROACH: This research will combine several approaches to quantify the variation in allelopathic activity among A. petiolata populations, and the impact of that variation on population dynamics and management strategies. Objective 1: Quantify variation in soil quality and allelopathic activity within and among A. petiolata populations, and determine cost-effective assays of allelopathic activity. I will collect A. petiolata seeds from 10 individuals, as well as soil samples, from 40 populations across a gradient of invasion age (5 in New York, 30 in Illinois and Michigan, 5 in Arkansas). Three native tree species will be grown in soil from each population to determine the current soil quality of each site. I will measure the glucosinolate concentrations (a likely allelochemical of A. petiolata) of greenhouse grown plants from each population. Additionally, I will grow the natives in soil cultured for one generation by A. petiolata individuals from each population to asses the current soil killing ability of each population, and will correlate this metric with the mean glucosinolate concentration of the population. Finally, I will use extracts of the A. petiolata plants from each population in a series of bioassays to determine cost-effective measures of allelopathic ability that managers could perform on specific populations. Objective 2: Determine how variation in allelopathy affects population growth and demography. Among the A. petiolata populations sampled for Objective 1 will be 13 populations (8 MI, 5 IL) in which detailed demographic data have been collected for the last 3 years. I will correlate my measures of allelopathic activity with measures of population growth and spatial spread for each population. I will additionally correlate allelopathic data with each transition rate to determine where in the lifecycle allelopathy is having the strongest effect, and to determine how allelopathic effects on demographic rates influence overall population growth rate. Objective 3: Compare the efficacy of alternative restoration and management practices in A. petiolata populations with high or low allelochemical concentrations. Using the data from Objective 1, I will select 5 high and 5 low glucosinolate populations. In each site, I will perform a 2x2 factorial experiment, crossing A. petiolata removal with soil restoration. Each site will include 16 1 square meter plots, half of which will have A. petiolata removed in the early spring. Six tree seedlings (two of each species) will be planted in each plot; in half of the plots, one individual per species will have been grown in live soil for four months prior to planting, while all others will have been grown in sterile soil. These seedlings will be followed for two growing seasons. Objective 4: Develop guidelines for prioritizing control and restoration efforts based on allelopathic activities and/or glucosinolate concentrations of specific populations. Decision tree analysis will be used to determine ranges of allelopathic activity/glucosinolate concentrations in which particular management strategies (A. petiolata removal and native plant/soil restoration) will be most successful.
 
CRIS NUMBER: 0211281 SUBFILE: CRIS
PROJECT NUMBER: ILLU-371-622 SPONSOR AGENCY: CSREES
PROJECT TYPE: NRI COMPETITIVE GRANT PROJECT STATUS: NEW MULTI-STATE PROJECT NUMBER: (N/A)
START DATE: Nov 15, 2007 TERMINATION DATE: Nov 14, 2009

GRANT PROGRAM: BIOLOGY OF WEEDY AND INVASIVE PLANTS
GRANT PROGRAM AREA: Plant Systems

CLASSIFICATION
Knowledge Area (KA)Subject (S)Science (F)Objective (G)Percent
123062010706.350%
136062010706.350%

CLASSIFICATION HEADINGS
KA123 - Management and Sustainability of Forest Resources
KA136 - Conservation of Biological Diversity
S0620 - Broadleaf forests of the North
F1070 - Ecology
G6.3 - Protect and Manage Forests and Rangelands


RESEARCH EFFORT CATEGORIES
BASIC 80%
APPLIED 20%
DEVELOPMENTAL (N/A)%

KEYWORDS: invasive species; garlic mustard; alliaria petiolata; allelopathy; glucosinolate; genetic variation; population dynamics; restoration

PROGRESS: Nov 15, 2007 TO Nov 14, 2008
OUTPUTS: Although this project has been underway for only one year, it has already produced several important outputs. A large greenhouse experiment testing for evolutionary change in allelopathic properties of garlic mustard has been completed, and a large, multi-site field experiment testing the efficacy of different management and restoration strategies has been established and monitored for one growing season. Results from these studies were presented at the annual meeting of the Ecological Society of America. I also presented some of these results to undergraduates through a guest lecture for the Association of Chicagoland Colleges, and to the general public at the Illinois Natural History Survey 150th anniversery Jamboree. PARTICIPANTS: Richard Lankau (PI) designed and performed the greenhouse and field experiments. Adam Davis (post-doctoral mentor) provided guidance on the design and analysis of data, as well as materials and equipment to perform the research. TARGET AUDIENCES: The target audiences for this project include other researchers, land managers, undergraduate students, and the general public. Efforts to address these target audiences to date include presenting data at the 2008 Ecological Society of America annual meeting, numerous discussions with the land managers at the 10 field sites, guest lectures in undergraduate classrooms, serving as a mentor for underrepresented minorities through the ESA SEEDS program, and providing information about invasive species to the general public at the Illinois Natural History Survey 150th Anniversary Jamboree. PROJECT MODIFICATIONS: Not relevant to this project.

IMPACT: 2007-11-15 TO 2008-11-14 Results from this project to date have provided significant improvements in the understanding of garlic mustard invasions. We have demonstrated that over many generations at a given site garlic mustard tends to reduces its investment in toxic allelochemicals. This genetic change toward reduced allelochemical concentrations led to weaker negative impacts on native tree seedling growth. Additionally, in a multi-site field experiment, we have seen that native tree seedling growth is higher in sites with a longer history with garlic mustard, and that the relative benefit of management (hand-pulling garlic mustard) and restoration (providing inoculations of healthy soil microbial communities) increased with the concentration of toxic chemicals in the garlic mustard population.

PUBLICATION INFORMATION: 2007-11-15 TO 2008-11-14
No publications reported this period

PROJECT CONTACT INFORMATION
NAME: Lankau, R.
PHONE: 530-848-9014
FAX: (N/A)