The distribution of invasive plant species of concern in the Kīlauea and Mauna Loa strip areas of Hawai‘i Volcanoes National Park, 2000-2010

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.Alien plant surveys conducted between 2000 and 2010 in Hawai‘i Volcanoes National Park quantified the distribution of 134 alien plant species over 87,908 ha between sea level and 4,169 m elevation. Searches were conducted by foot, vehicle and helicopter and incorporated past survey and control data. Mapping identified 33 widespread species distributed broadly across the park and 101 locally distributed species with fewer, more discrete populations. Sixteen species were incipient invaders not previously known from the park, and an additional 15 new species were identified in a separate survey by Pratt et al. Relatively high concentrations of invasive species were found along roadsides and trails, particularly in the Kīlauea summit area, `Āinahou, the Mauna Loa rock quarry and Highway 11, where heavy visitation, high traffic, and importation of road building materials likely facilitated introduction and spread of species from outside areas. A geodatabase documenting the distribution of these species was generated, and survey data were compared to previous studies (Fosberg 1966; Tunison et. al. 1992) to evaluate changes in distribution and serve as a baseline for monitoring. Relative to the last parkwide mapping of localized species completed in 1992, eight species managed to control populations were found to have increased in abundance, while 30 apparently became less abundant. Thirteen managed species could not be relocated and may be extirpated. Key management recommendations based on survey results include expanding control to 13 additional species identified during this study, quickly eradicating all newly discovered species before they spread, intensifying monitoring in high risk areas, and expanding pre-emptive measures such as sanitation, public education, and prevention of deliberate plant introductions to the park