Comparisons of Chlorophyll Content and Leaf Structure in Arctic and Alpine Grasses

Grasses under natural conditions from arctic and alpine tundras were compared with respect to pigment content, leaf density- thickness, and width. General differences between arctic and alpine grasses were not large. The higher fresh weight to dry weight ratios in arctic plants were reflected in slightly higher density-thickness values on a fresh weight basis and lower values when based on dry weight. In both tundras, grasses with low density-thickness values were characteristically found in very wet and/or protected habitats, whereas those with higher values occupied drier and more open sites. The correlation between density-thickness and leaf thickness was high, especially on a fresh weight basis. Leaf width appeared greater in the Arctic. Chlorophyll contents differed most markedly on a dry weight basis with arctic grasses possessing the highest concentrations. When based on fresh weight and area, differences were not readily apparent. Chloro- phyll on an area basis was strongly correlated with fresh weight density- thickness. The ratios of chlorophyll a to b were low in plants from the Arctic. Within either region the ranges for pigment contents and other leaf measurements were large, but the above correlations were found both be- tween species and within species.