Juliana Grinvalsky
Wild Rice Community Dynamics and Population Biology of Eriocaulon parkeri (Parker’s pipewort)
Advisor: John Lichter
The first part of the study is long term monitoring of the plant communities in the intertidal zone Merrymeeting Bay. Although the waters of the bay are subject to tidal variation, the system is freshwater, which allows a greater diversity of plant species in the bay than if limited by salinity. Vegetation is identified and quantified at 8 fifty-meter transects around the bay at the beginning of each month during the summer growing season (June-September). In particular, we observe the dynamics between annual species, such as Zizania aquatica (wild rice), and perennial species such as Schoenoplectus tabernaemontanii (soft-stemmed bulrush) and Schoenoplectus pungens (three-squared sedge). Wild rice dominates the plant community in terms of plant density per square meter, and qualitatively, the growth of this annual from a seed to over 7’ tall in a few months contributes most of the primary productivity of the system. For each of the transects, the pattern of wild rice survival through a growing season is also described. Abundant wild rice growth historically was attributed to the poor water quality of the bay, and a fertilization experiment will determine if the addition of inorganic nitrogen and phosphorus sources causes an increase in wild rice biomass. Seed production is quantified at the end of the season using seed traps and seed collected is used to conduct seed germination experiments in the lab.
In addition to the general plant community surveys, a study of the reproductive and population biology of Eriocaulon parkeri was initiated this summer. This part of the study is being funded by the New England Wildflower Society with funds available from the National Science Foundation to support studies that will aid the conservation of endangered or threatened plant species. Eriocaulon parkeri is ranked by the Maine Natural Areas Program as being rare, and the plant has a global ranking of G3. Merrymeeting Bay is one of the largest populations of this plant worldwide. Populations of this species will be marked and mapped in the field and in situ observations of floral development will help to identify pollination mechanisms. A pollinator exclusion experiment will provide information on whether the plant is self-pollinated or entomophilous. At the end of the season, collected seeds and plants will be used in the lab to conduct germination studies and microscopic analysis of pollen and reproductive mechanisms.