Algal mat productivity: Comparisons in a salt marsh

This paper documents the role of salt marsh algal mats in the productivity of a southern California tidal wetland. The productivity of the mats, which are composed of filamentous bluegreen and green algae and diatoms, varies both temporally and spatially in relation to tidal inundation and overstory vegetation. The estimates of net primary productivity (NPP) were highest under the canopy ofJaumea carnosa (Less.) Gray (341 g C m^?2 yr^?1) at low elevation. Elsewhere, NPP appeared to be limited by low light (276 g C m^?2 yr^?1 underSpartina foliosa Trin.) and desiccation (185 g C m^?2 yr^?1 underBatis martima L. and 253 g C m^?2 yr^?1 underMonanthochloe littoralis Engelm). Algal NPP was from 0.8 to 1.4 times that of the vascular plant overstory NPP. It is hypothesized that the arid environment of southern California and resulting hypersaline soils reduce vascular plant cover, which leads to high algal productivity.