Japanese Spirea Control With Herbicides in the Big South Fork NRRA

The Big South Fork watershed is a national focus for major conservation efforts because of its aquatic and telTestrial features. The river is particularly significant in that it harbors 23 species of mussels. five of\vhich are federally listed. One fish and two river-dependent plants are also federally listed. Coal extraction and water quality issues are the primary threat to the river system: however. an emerging exotic plant infestation also poses a significant threat to the river gorge communities. The effects of exotic plants on vegetation structure and composition are increasingly apparent on the river bank, alluvial floodplain, and mesic lower gorge slope. This project will focus on protocol development and monitoring the effects of herbicide applications in sensitiYe gorge plant communities. Because of its influence on community structure and apparent rapid rate of spread, we intend to focus on the invasive shrub. Spiraeajaponica (Japanese spiraea). Japanese spiraea is abundant in the alluvial floodplain woods and gorge toeslope. particularly concentrated along trails. old roads. and old homesites. Spreading from their points of origin, Japanese spiraea colonies are encroaching into floodplain forests and knov.-n occurrences of rare plant populations. The gorge toeslope. floodplain, and riparian shrub zone host a suite of rare plant species. The mesic toeslope is habitat for Euphorbia mercurialina (Cumberland spurge), Hexastylis contracta (southern heartleaf), Hydrastis canadensis (goldenseal), Juglans cinerea (butternut), Panax quinquejhlius (ginseng). Polygala cruciata (gaywings). and others. The alluvial floodplain contains Aconitum uncinatum (blue monkshood). Boykinia aconitifolia (brook saxifrage). Chl}'.wgonul11 virginianul11 (green-and-gold), C)lpripedium kentuckiense (Kentucky lady's slipper) and others. The riparian shrub zone includes Eurybia saxicastellii (Rockcastle aster). Fothergilla major (mountain witchalder), and Spiraea virginiana (Virginia spiraea). Although Japanese spiraea does not seem to establish major colonies on river cobble bars. it is frequently observed in the shrubby cobble bar margins. Big South Fork cobblebars are inhabited by a unique assemblage of plants. many of which are rare: COl1radina verticil/ata (Cumberland rosemary). Comptol1ia peregrina (sweetfern), kfarshallia grand{flora (large-flowered Barbara 'sbutton). Solidago randii (Rand's goldenrod). and others. Several of these species are unique to the Cumberland Plateau and are not well protected in a natural area other than Big South Fork NRRA. This project will examine Japanese spiraea treatment methods and the effects of those treatments on alluvial floodplain plant communities on the Big South Fork. Although chemical treatment techniques have proven effective for controlling the targeted species. the sensitivity of the affected riparian zone walTants careful examination of these methods. Our review of the literature revealed no documented studies that examine the direct effects of herbicide use on nontarget plant species/communities in these types of habitats.