Technical Report #167. Loh, R., A. Ainsworth, T. Tunison, and C. D’Antonio. September 2009. Testing native species response to fire – a first step towards building fire resilient native plant communities at Hawai’i Volcanoes National Park

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Wildfires, fueled by fire-adapted alien grasses, result in the loss of native tree and shrub species in the dry and seasonally dry communities of Hawai‘i Volcanoes National Park. Future wildfires and further loss of native plant diversity is expected given the prevalence of alien grasses in the area. Fire-tolerance, defined in this paper as the ability to survive or colonize after fire, was evaluated in seven controlled burns. Seed germination in response to oven heating was tested in laboratory experiments. Fourteen of 19 native species showed some capacity to survive or colonize after fire. Seedlings of eleven species were able to establish from seeds placed in the field prior to or immediately following controlled burns (Argemone glauca, Bidens hawaiensis, Canavalia hawaiiensis, Dodonaea viscosa, Myoporum sandwicense, Osteomeles anthyllidifolia, Santalum paniculatum, Scaevola kilaueae, Sida fallax, Sophora chrysophylla, Sesbania tomentosa). Seven species survived beyond the first year including six that reached reproductive maturity (Argemone glauca, Bidens hawaiensis, Canavalia hawaiiensis, Dodonaea viscosa, Sida fallax, Sophora chrysophylla). Seeds of ten species tested in oven-heating experiments showed either a positive or neutral germination response to mild heating (90 ºC), among these were three species (Myrsine lanaiensis, Rhus sandwicensis, Senna gaudichaudii) not tested in the field. Testing species response to fire is the first step toward building resilient native plant communities in the new fire regime established by alien grasses at HAVO.