Lipid Properties of Carex aquatilis from Hot Spring and Permafrost‐Dominated Sites in Alaska: Implications for Nutrient Requirements

Abstract

AbstractSelected lipid properties were compared between populations of Carex aquatilis occupying adjacent hot spring and permafrost‐dominated sites in interior Alaska. Analyses were carried out on a variety of plant parts and results correlated with prevailing ambient temperature. Phospholipid concentrations were higher in plants from permafrost than from hot spring areas, even though there was no consistent interpopulation difference in total lipid content. The population differences in phospholipid content were greatest in those plant parts that experienced the greatest interpopulation temperature difference. Despite lower soil phosphorus availability, permafrost plants had higher total phosphorus concentrations, and a larger proportion of their phosphorus was contained in phospholipid than in hot spring plants. There was no consistent relationship between the proportion of various classes of phospholipids present and prevailing ambient temperature. Fatty acid chain length and degree of unsaturation of the phospholipid fraction were inversely correlated with temperature both between populations and among plant parts. No such relationship was found in the fraction containing neutral lipids. We suggest that the high tissue phosphorus content that characterizes northern plants may be necessary in part to maintain large quantities of phospholipid‐containing membrane. Increased amounts of membrane in turn may be a prerequisite for the high rates of membrane‐associated processes characteristic of plants in the cold subarctic environment.