James B. McGraw

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Growth, survival and reproduction of adult plants from three reciprocally-transplanted populations of Dryas octopetala were followed over a seven year period, from 1979 to 1986. The two most different ecotypes, from snowbed and fellfield environments, were strongly selected against in extreme foreign environments via differential growth, survival, and(More)
Multiple-regression techniques for measuring phenotypic selection have been used in a large number of recent field studies. One benefit of this technique is its ability to discern the direct action of selection on traits by removing effects of correlated traits. However, covariation among traits expressed at different stages in an organism's life history is(More)
American ginseng (Panax quinquefolius L.) is an uncommon to rare understory plant of the eastern deciduous forest. Harvesting to supply the Asian traditional medicine market made ginseng North America's most harvested wild plant for two centuries, eventually prompting a listing on CITES Appendix II. The prominence of this representative understory plant has(More)
American ginseng is the premier medicinal plant harvested from the wild in the United States. In this study, seven populations of ginseng plants were censused every 3 weeks during the growing season over 5 years to monitor deer browse and harvest and to project population growth and viability. The minimum viable population size was approximately 800 plants,(More)
Plant growth rate is often assumed to be an ecologically important life history trait. However, conventional plant growth analysis, while providing a useful accounting of rates of weight gain and its components, is ill-suited for testing relationships between growth and fitness, particularly in natural populations. Two new approaches that are suitable for(More)
Increasing rates of forest disturbance may provide greater opportunity for invasion of nonnative species, thereby altering the successional trajectory of native plant communities. In the eastern U.S., invasive Ailanthus altissima and native Liriodendron tulipifera have similar life histories and niches and often co-occur. To examine how disturbance affects(More)
For rare plants, self-pollination and inbreeding can increase in small populations, while unusual levels of outcrossing can occur through restoration efforts. To study both inbreeding and outcrossing, we performed experimental pollinations using Panax quinquefolius (American ginseng), a wild-harvested plant with a mixed mating system. For inbreeding, plants(More)
Bioclimatic envelope models of species' responses to climate change are used to predict how species will respond to increasing temperatures. These models are frequently based on the assumption that the northern and southern boundaries of a species' range define its thermal niche. However, this assumption may be violated if populations are adapted to local(More)
Ailanthus altissima has a long history of invasion in urban areas and is currently spreading into suburban and rural areas in the eastern U.S. The objectives of our study were to (1) determine whether A. altissima seed dispersal distance differed between populations on the edges of open fields and intact deciduous forest, and (2) determine whether dispersal(More)