The tallgrass prairie is one of the most severely affected ecosystems in North America. As a result of extensive conversion to agriculture during the last century, as little as 1% of the original tallgrass prairie remains. The remaining fragments of tallgrass prairie communities have conservation significance, but questions remain about their viability and importance to conservation. We investigated the effects of fragment size, native plant species diversity, and location on invasion by exotic plant species at 25 tallgrass prairie sites in central North America at various geographic scales. We used exotic species richness and relative cover as measures of invasion. Exotic species richness and cover were not related to area for all sites considered together. There were no significant relationships between native species richness and exotic species richness at the cluster and regional scale or for all sites considered together. At the local scale, exotic species richness was positively related to native species richness at four sites and negatively related at one. The 10 most frequently occurring and abundant exotic plant species in the prairie fragments were cool‐season, or C3, species, in contrast to the native plant community, which was dominated by warm‐season, or C4, species. This suggests that timing is important to the success of exotic species in the tallgrass prairie. Our study indicates that some small fragments of tallgrass prairie are relatively intact and should not be overlooked as long‐term refuges for prairie species, sources of genetic variability, and material for restoration.

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As a result of water-level regulation, cattails have invaded sedge/grass meadow in all wetlands on Lake Ontario. Even with a change in water-level-regulation to a more natural hydrologic regime, restoration requires methods for active cattail management without the ability to manipulate water depths and without imperiling other vegetation. We conducted replicated studies at a wetland site with an active invasion front in zones of nearly mono-dominant cattail and transitional invasion. We tested various combinations of cutting cattail ramets when carbohydrate reserves were minimized, spraying cut stems with herbicide, slicing rhizomes to mimic tilling, and hand-wicking resprouted ramets with herbicide. We also collected companion environmental data. The most effective treatment in both zones was cutting during the period with reduced rhizome carbohydrates followed by handwicking resprouted ramets with herbicide in late summer, which allows the herbicide to be absorbed by the rhizomes. Two years of treatment provide the best results, reducing cattail stem counts and cover by more than 50%, but follow-up applications in ensuing years may be warranted to treat surviving cattails. Given the widespread problem of cattail invasion, these treatments may have broad application in wetlands where water levels cannot be manipulated.

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The relationships between plant species composition and dispersion, water chemistry and water depth/depth to water table were studied in five calcareous intradunal ponds (pannes) bordering the southern tip of Lake Michigan. The panne systems contained eight plant species threatened and endangered in Indiana. The aquatic zone was dominated by Chara, the pond edge by Rhynchospora capillacea, Juncus balticus and Utricularia cornuta, and the area surrounding the pond by Hypericum kalmianum. The water chemistry was typical of hardwater ponds in the area, probably affecting species composition but not species dispersion within the pannes. A significant correlation between the first axis scores from a reciprocal-averaging ordination and water depth/depth to water was demonstrated. Panne species are fitted to a model based on hydrology proposed by van der Laan for dune-slack vegetation in the Netherlands.

In a changing-criterion design increased running speed by a handicapped youth was demonstrated by establishing a temporal criterion for running, which changed repeatedly as running matched the criterion. Reinforcement and avoidance procedures were made contingent on running and were effective in increasing running speed. Follow-up data at 3 and 12 mo. indicated maintenance of the increased running speed.