Net Photosynthesis, Respiration, and Production of the Moss Sanionia uncinata on a Glacier Foreland in the High Arctic, Ny-Ålesund, Svalbard

Abstract

As part of the study on carbon cycling in a deglaciated area in the High Arctic, Ny-Alesund, Svalbard (79°N), we examined the effects of abiotic factors on the net photosynthesis and dark respiration rates of the dominant moss Sanionia un-cinata (Hedw.) Loeske. The rates of net photosynthesis (Pn) and dark respiration (R) were measured using an open-flow gas exchange system with an infrared gas analyzer in the snow-free season of 2000. High photosynthetic activities were observed only in rainy days or soon after rainfall, when moss water content was high. Under a sufficiently humid condition, Pn determined at near light saturation was almost constant over a wide temperature range from 7 to 23°C, while R increased with temperature with a QIO value of 3.0. Based on the relationships between abiotic factors and the CO 2 exchange rate, we estimated the net primary production (NPP) of the moss in the snow-free season using the meteorological data obtained over 6 yr (1995-2000). The mean, minimum, and maximum values of NPP for the 6-yr period were 17, I, and 30 g dry wt. m ? snow-free season:", respectively. It was suggested that NPP of the moss in this area varied widely between years' depending primarily on water availability.