Measurement of cordgrass, Spartina alterniflora, production in a macrotidal estuary, Bay of Fundy

A one-year field study was conducted of the growth, mortality, and loss dynamics of a Spartina alterniflora low marsh in the Minas Basin, a macrotidal estuary at the head of the Bay of Fundy. Data were used to examine the suitability of four methods for estimating annual net aerial primary production (NAPP) of a marsh subject to energetic tidal flooding. Shoots start to grow in April and reach maximum height (about 0.5 m) and weight in October. Maximum shoot density 900-1,600 m-2 occurs around June and drops thereafter due to the export of entire shoots. The average shoot produces about seven leaves and at least 2-3 are lost during the growing season. All remaining vegetation dies before the end of November. Methods based on harvesting vegetation under-estimated NAPP, especially at lower elevations where export is greater due to more frequent and prolonged tidal flooding. The highest NAPP values, on the order of 500-600 g m-2 y-1 were obtained using methods based on the population dynamics of individual shoots. These methods are recommended for energetic tidal environments because they include the production of vegetation exported during the growing season.