Pigment Structure of Some Arctic Tundra Communities

An analysis of four tundra communities in northern Alaska indicates that the chlorophyll contents (0.32—0.77 g/m 2 ) of these communities are similar to those reported from alpine tundra and from temperate grasslands of similar height. There was a high correlation within each community between chlorophyll content (g/m 2 ) and the dry weight (g/m 2 ) of the plant material. In different communities, however, chlorophyll on a dry weight basis varied from a low of 1.5mg/g in Dry Sedge tundra to a high of 8.8 mg/g in Wet Sedge tundra. The communnities with the lowest amounts of total chlorophyll had the greatest amounts of chlorophyll in the moss and ericaceous components of the vegetation. For example, in Dry Sedge tundra about one—third of the chlorophyll was in the ericaceous component of the vegetation and about one—third was in the moss layer. Wet Sedge tundra, which possessed 0.77 g/m 2 , included no ericaceous material and only about 2% of the chlorophyll was in the moss layer. The ratios of chlorophyll a:b generally ranged between 1.5 and 2.5 and were lowest in the mosses and usually highest in the non—ericaceous components. The a:b and carotenoid ratios were very similar within each component of the four communities investigated, and the low a:b ratios are interpreted as an adaptation to lower light intensity in the Arctic. The evidence emphasized the importance of a bryophyte synusium in some Arctic communities.