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Abstract

Lake Fayetteville and Lake Wedington are small reservoirs of about the same size and age that are located in northwestern Arkansas. We collected macrophytes from eleven transects around each reservoir in the autumn of 1993. Justicia (waterwillow), Typha (cat-tail), Scirpus (bulrush), Potamogeton (pondweed), and Zannichellia (horned pondweed) occur in both reservoirs. Justicia occurs most commonly in both reservoirs. The macrophytes of Lake Wedington are organized in a characteristic zonation pattern with bands from shore toward open water of emergent, floating-leaved, then submersed macrophytes. Macrophyte zonation was not as evident in Lake Fayetteville because of the low occurrence of floating leaved and submersed macrophytes in1993. Early studies of Lake Wedington found that the dominant macrophytes were Cyperus, Echinochloa, Lotus, and Sagittaria, all of which were absent during this study. Potamogeton, Scirpus, and Typha were also found to be dominant during 1952 studies, but occurred in lesser amounts in the current study. Previous studies (1956, 1967, 1977) on Lake Fayetteville stated that Sagittaria and Nelumbo were dominant macrophytes, but we found none in1993. Juncus, Potamogeton, Scirpus, and Typha were common in the early studies but occurred infrequently in our collections. Macrophyte composition in Lake Fayetteville in 1993 was attributable to an herbicide application that occurred in spring, 1992. As for the changes in Lake Wedington, we assume that the Justicia has out-competed those macrophytes that were in the reservoir in1952, or that normal lake ontogeny during the intervening 40 years has altered habitat conditions to now favor Justicia.

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