Net aerial primary production of a James Bay, Ontario, salt marsh

Abstract

Aboveground plant biomass and litter measurements were made at four intervals between mid-June and late August 1977 on a subarctic salt marsh located at North Point on the southwestern shore of James Bay, Ontario. We sampled six salt marsh zones ranging from a lower intertidal flat dominated by the grass Puccinellia phryganodes to the edge of willow thickets characterized by Juncus balticus.Peak aboveground biomass was reached in nearly all zones by early August, and ranged from 119.3 to 240.4 g dry weight∙m⁻². Litter accumulated in all zones except the lower two zones which were subjected to tidal flows. The highest zone where Juncus balticus occurred had the highest litter mass, 572.8 g dry weight∙m⁻², while the lowest, 24.7 g∙m⁻², occurred in the lowest zone. Estimates of net aerial primary productivity using Smalley's method ranged from 119.3 g∙m⁻² in the upper salt marsh to 384.0 g∙m⁻² in the zone dominated by Juncus balticus. The mean marsh net aerial primary productivity was 227.7 g∙m⁻² which was low compared with other salt marsh data. The 1977 aboveground biomass was lower in 1976, probably as a result of a cooler summer.