No abstract

Historical and current ecological and genetic factors were examined in western popultions of Eriocaulon kornickianum to determine the cause and consequence of rarity in this disjunct species and to assess its extinction vulnerability. Reproductive biology was examined, which included an examination of breeding systems, seed set, and pollen viability. Recruitment into and maintenance of the populations was evaluated using seed bank estimates. A disturbance study was conducted that examined the effects of competing vegetation and associated species, and included clipping, burning, and artificial seeding. Enzyme electrophoresis was used to measure genetic variation in an effort to examine gene flow within and among populations. Many factors are contributing to the decline of the western populations of this species and include an annual or weak perennial life history, no vegetative reproduction, low seed set, little seed bank contribution to population growth and maintenance, genetic homogeneity, a restricted habitat, and poor competitive abilities. Continuing studies of genetic variation are being used to examine historical factors that may have resulted in a genetic bottleneck observed in the western populations.

Although southeastern Oklahoma has substantial areas of bottomland forest, few studies exist of this vegetation type. We analyzed forest community structure at the Tiak Research Natural Area of the Ouachita National Forest on the Upper Gulf Coastal Plain. Vegetation data were collected from 24 12m x 8m macroplots. Percent cover data were recorded for ferns, fern-allies, and herbaceous angiosperms. Tree sapling and shrub species were recorded in diameter classes, and numbers of stems in estimated height classes were recorded for midlevel and canopy trees. One hundred fifty-two taxa of woody and herbaceous plants were encountered. Toxicodendron radicans and Arundinaria gigantea were the common understory species. Acer rubrum, A. saccharum, Carpinus caroliniana, Carya alba, C. texana, Cornus florida, Fraxinus americana, Liquidambar styraciflua, and Nyssa sylvatica were common as mid-level species. Quercus lyrata and Q. phellos were the most common canopy layer trees.