Hydrarch succession and net primary production of oxbow lakes in central Alberta

Abstract

The plant communities in a series of 15 oxbow lakes were examined to determine their successional sequence and productivity. Twelve communities were recognized as a result of analyses carried out on the phytosociological data. Water chemistry and water level fluctuations caused by periodic flooding are the major factors controlling plant distribution and succession.The maximum above-ground standing crop of communities follows a definite pattern with succession: from submerged (ca. 200 g/m2), through floating-leaved (ca. 210 g/m2), to the emergent community (ca. 465 g/m2), there is a stepwise increase in annual production, which declines in the meadow community (ca. 325 g/m2).Leaf area index does not change with succession: it remains between 3 and 4 in all the stages examined. Chlorophyll follows a pattern similar to standing crop, except that submerged communities contain more chlorophyll than floating-leaved: submerged (0.24–0.92 g/m2), floating-leaved (0.29–0.80 g/m2), emergents (0.62–2.13 g/m2), and meadow (0.54–1.42 g/m2).