Mineral composition of Phragmites australis in Scottish lochs as related to eutrophication. I. Seasonal changes in organs

Monthly levels of nitrogen, phosphorus, potassium, sodium, calcium, magnesium and iron in the organs (root, rhizome, stem, leaf and panicle) of Phragmites australis were determined from March to November, 1975 in Forfar Loch (polytrophic), Balgavies Loch (eutrophic) and Loch of the Lowes (mesotrophic), Scotland. Generally no consistent seasonal changes in the mineral levels were detected for the root, rhizome and panicle. For the stem and leaf, the levels of nitrogen, phosphorus, potassium, calcium and magnesium rose to a peak before declining for the rest of the season. Consistently higher levels of tissue nitrogen, phosphorus, potassium and calcium were found in the Forfar plants over those of Balgavies and Lowes, reflecting the very eutrophic condition in Forfar Loch. The mineral compositions in the reeds in the present study were compared with similar studies in other areas.