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Harvard Forest Research Project 2022

  • Title: Garlic mustard responses to global change
  • Principal investigator: Michelle Jackson (
  • Institution: University of Massachusetts - Amherst
  • Primary contact: Michelle Jackson (
  • Team members: Kristina Stinson
  • Abstract:

    Extensive research over the past 30 years has recognized several long-term ecological impacts associated with the invasive Eurasian forb Alliaria petiolata (garlic mustard; hereafter GM) on native plant and soil communities throughout the Northeast. GM’s production of phytochemicals, specifically the glucosinolate compound sinigrin, have been identified as particularly disruptive to native plant-mycorrhizal associations. In addition to this physiological mechanism enabling GM to be extremely competitive against native plants, recent models suggest that under certain future climate scenarios GM may be able to further expand its geographic range. Among the different shifts in abiotic conditions predicted under global change that may impact this species, the effects of soil warming (SW) and increased available nitrogen (N) on GM traits have not been adequately quantified. I propose a research program to investigate GM trait responses across life stages to SW + increased N that will incorporate the collection of GM seedlings from three sites across Massachusetts with varying mean annual temperatures that will be transplanted into a lath house at Harvard Forest. Utilizing a factorial design, the GM seedlings will be organized into 4 treatments with ~60 seedlings/treatment. Soil warming mats and a nitrate solution will be used to create the proposed treatment conditions which will include: a control, increased SW conditions, increased N conditions, and a combination of increased SW + N conditions. GM trait responses will be quantified by measuring a variety of physiological traits that correspond with growth and development. The collation of GM seedling leaf size and number will be supplemented with data on sinigrin concentration present collected using high-performance liquid chromatography (HPLC) methods to address the following question: Does GM seedling exposure to increased SW + N conditions impact the amount of sinigrin produced? A subset of the GM seedlings will be maintained in the lath house after the summer growing season without the initial treatment conditions to overwinter so that they may reach reproductive maturity. I will repeat the same procedure using soil warming mats and a nitrate solution on GM adults in the lath house the following summer, to measure similar trait responses to these conditions. In addition to leaf measurements and sinigrin concentration, biomass will also be calculated. Finally, I will investigate the GM trait responses I collected during the duration of my experiments to explore possible ecotypic variation among GM specimens from the three different sites in Massachusetts.