Individual plant performance, understory, and rust data for restoration plantings of Metrosideros polymorpha in Rapid ʻŌhiʻa Death-affected forests on Hawaii Island, 2019-2022

Rapid ʻŌhiʻa Death (ROD), caused by the fungal pathogen Ceratocystis, is killing large numbers of ʻōhiʻa trees (Metrosideros polymorpha) in Hawai‘i. ‘Ōhiʻa is the dominant canopy forest species across many different soil types and climatic conditions and makes up the majority of biomass in native-dominated Hawaiian forests. This study tested whether planting ʻōhiʻa seedlings is viable in areas with high ROD mortality, and how mortality rates due to ROD compare to those of other stressors, such as competition with invasive plants and damage from invasive ungulates.

We planted ʻōhiʻa across three climatically different ROD-affected forest sites and crossed this with weeding and fencing treatments. We also tracked seedlings in ʻōhiʻa restoration plantings in two additional sites without weeding and fencing treatments. In all cases, we monitored seedlings monthly and immediately tested dead seedlings for viable Ceratocystis spores.