THE EFFECT OF FIRE ON GAS-EXCHANGE AND ABOVEGROUND BIOMASS PRODUCTIONIN ANNUALLY VS BIENNIALLY BURNED SPARTINA-PECTINATA WETLANDS

Photosynthetic and growth responses of Spartina pectinata were compare d in annually and biennially burned wetlands in a northeastern Kansas tallgrass prairie. Photosynthetic CO2 uptake was consistently higher i n Spartina pectinata in annually burned wetlands, and there was a seas onal difference in maximum photosynthetic rates. Plants in annually bu rned wetlands reached a maximum photosynthetic rate of 38.2 mu mol m(- 2) s(-1) in late spring, while maximum photosynthesis in plants of bie nnially burned wetlands was 28.6 mu mol m(-2) s(-1) in late summer. Cu lm density in these wetlands was not affected by fire; however, aboveg round biomass production, inflorescence density and plant height at an thesis were significantly greater in annually burned wetlands. These r esults indicate that Spartina pectinata may be a fire-dependent specie s, with post-fire responses similar to the dominant grasses in tallgra ss prairie as well as other Spartina congeners.