National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Established Invasive Plant Species Monitoring Hawai‘i Volcanoes National Park Natural Resource Report NPS/PACN/NRR—2016/1202 ON THE COVER Former wet forest in Kahuku, Hawai‘i Volcanoes National Park. Photograph by Inventory & Monitoring Vegetation Crew, Hawai‘i Volcanoes National Park. Established Invasive Plant Species Monitoring Hawai‘i Volcanoes National Park Natural Resource Report NPS/PACN/NRR—2016/1202 Melissa J. Simon, Jacob Gross, and Alison Ainsworth National Park Service Pacific Island Network – Inventory & Monitoring Program PO Box 52 Hawai‘i National Park, HI 96718 April 2016 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a range of reports that address natural resource topics. 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Please cite this publication as: Simon, M., J. Gross, and A. Ainsworth. 2016. Established invasive plant species monitoring: Hawai‘i Volcanoes National Park. Natural Resource Report NPS/PACN/NRR—2016/1202. National Park Service, Fort Collins, Colorado. NPS 124/132348, April 2016 ii Contents Page Figures.................................................................................................................................................... v Tables ................................................................................................................................................... vii Appendices ........................................................................................................................................... vii Abstract ................................................................................................................................................. ix Acknowledgments ................................................................................................................................. xi Acronyms .............................................................................................................................................. xi Introduction ............................................................................................................................................ 1 Methods .................................................................................................................................................. 3 Study Sites ...................................................................................................................................... 3 Wet Forest ................................................................................................................................. 4 Subalpine Shrubland .................................................................................................................. 8 Non-native Plant Sampling........................................................................................................... 11 Data Analysis................................................................................................................................ 12 Non-native Species Richness .................................................................................................. 12 Non-native Frequency ............................................................................................................. 12 Non-native Cover .................................................................................................................... 12 Results .................................................................................................................................................. 15 Non-native Species Richness ....................................................................................................... 15 Non-Native Frequency and Cover ................................................................................................ 22 Wet Forest ............................................................................................................................... 23 Nāhuku/East Rift ..................................................................................................................... 25 ʻŌlaʻa ....................................................................................................................................... 26 Kahuku WF ............................................................................................................................. 28 Subalpine Shrubland ................................................................................................................ 31 Discussion ............................................................................................................................................ 33 Wet Forest .................................................................................................................................... 33 Nāhuku/East Rift ..................................................................................................................... 33 ʻŌla‘a ....................................................................................................................................... 34 iii Contents (continued) Page Kahuku WF ............................................................................................................................. 35 Subalpine Shrubland ..................................................................................................................... 36 Conclusions .......................................................................................................................................... 39 Recommendations ................................................................................................................................ 39 Literature Cited .................................................................................................................................... 41 iv Figures Page Figure 1. Hierarchy of the EIPS sampling locations for HAVO ........................................................... 3 Figure 2. Nāhuku/East Rift sampling frame of HAVO wet forest plant community............................ 5 Figure 3. ʻŌlaʻa sampling frame of HAVO wet forest plant community. Points represent start locations of sampled transects (1000 m). ....................................................................................... 7 Figure 4. Kahuku WF sampling frame of HAVO wet forest community. Points represent start locations of sampled transects (250 m). ......................................................................................... 8 Figure 5. Subalpine shrubland sampling frame of HAVO. Points represent start locations of sampled transect (500 m). ................................................................................................................ 10 Figure 6. Species accumulation curves (sample-based rarefaction and extrapolation) and associated 95% confidence intervals for the two plant communities monitored at HAVO ................. 20 Figure 7. Species accumulation curves (sample-based rarefaction and extrapolation) and associated 95% confidence intervals for the two plant communities monitored at HAVO ................. 20 Figure 8. Species accumulation curves (sample-based rarefaction and extrapolation) and associated 95% confidence intervals for the three sampling frames within the wet forest plant community .................................................................................................................................