Bocconia frutescens distribution on the Island of Hawai`i

Abstract

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in. Bocconia frutescens, or plume poppy, is a large erect shrub listed as a noxious weed by the State of Hawai`i. Surveying was conducted in 2003 to document the distribution and population densities in Wood Valley (Ka`ū District), Honomolino and Manukā (South Kona District). Ground surveying was conducted along 80 transects in addition to roadside and aerial surveying. Bocconia was distributed across 1,522 ha in Wood Valley, 82 ha in Honomolino, and 34 ha in Manukā. Bocconia was a severe pest within young (5 to 10-m tall) Eucalyptus plantations in Wood Valley, with fruiting individuals observed in all sampled parcels. Lower plant densities were observed in interiors of mature Eucalyptus forest adjacent to severely infested plantations, principally in gaps and streambeds, suggesting an affinity for high light levels and soil disturbance. Cane lands harbored mature Bocconia, although at a much lower density than Eucalyptus plantations, with less than 100 individuals/ha versus greater than 500 individuals/ha. Higher densities were observed along roadsides within cane lands. Bocconia was not observed within native, closed-canopy `ōhi`a and koa forests in the adjacent Ka`ū Forest Reserve, except along one jeep trail. Bocconia populations in Honomolino occur in a mosaic of habitats including rangelands, `ōhi`a forest and woodlands and residential areas. Bocconia at Manukā occurs primarily in `ōhi`a-dominated native mesic forest. This project was carried out under a cooperative agreement with the Pacific Cooperative Studies Unit, University of Hawai`i at Mānoa.