Kawainui Marsh functions as vital habitat for endangered native species, essential flood control, and as a socio-culturally important place. The Kawainui Marsh Restoration Project is an 80-acre site surrounding the Kahanaiki Stream inlet to the 830-acre marsh. Long-term residual effects of intensive agriculture, invasive species explosions, and rapid urbanization speak to the dynamism of the system, resiliency of our persisting endemic fauna, and the uncertainty of Kawainui’s future. The Hawaiʻi Department of Land and Natural Resources have stated invasive species is a top priority and primary impediment to restoration. To help managers with this issue, my study answers the following questions: (1) How has the vegetation community of the site changed? (2) What invasive plant species are currently present within the restoration project area and how do communities differ? (3) What are the most effective and practical recommendations for invasive species management and native plant restoration in Kawainui Marsh? The historical ecology analysis examines environmental change through time with a goal of informing future decisions utilizing both social and biophysical sciences. The invasive and restoration plant community analysis determined dominant invasive species from randomized quadrat blocked surveys. Finally, I created an invasive and restoration plant management recommendation report to integrate understanding from historical ecology analysis with present day survey results to inform effective management of this highly altered system.
Results/Conclusions
The historical ecology analysis really provides the manager with a wide variety of reference system options. Just a small glimpse into Kawainui’s past can reveal its transformation from bay to inland lagoon to revered Polynesian aquaculture complex and finally through a period of intensive rice and pasture cultivation to reach today’s conditions. The invasive plant surveys identified major invaders as California grass (Urochloa mutica), Guinea grass (Megathyrsus maximus), maile pilau (Paederia foetida), cattail (Typha spp.), and umbrella sedge (Cyperus spp.). Some restoration species identified include ʻuki (Cladium jamaicense), makaloa (Cyperus laevigatus), ‘ahuʻawa (Cyperus javanicus), and milo (Thespesia populnea). The management recommendation report essentially found that managers may require some trial-and-error as this site is novel and stilll evolving to our ever changing environment. I suggested a multi-layered approach focusing initatives on small patch invasive plat removal along the edges of the marsh with companion planting of restoration species with supplemented non-native non-invasive plants utliizing community workdays. Working in these small islands can allow for future research opportunities comparing management treatments, while employing sound ecological theory.