Quantifying the effects of Rapid ‘Ōhi‘a Death on Hawaiian Forest Bird Communities

Personnel: Dr. Kristina Paxton and Dr. Patrick Hart

Funding Source: National Science Foundation

Increasing rates of climate change, along with insect and pathogen infestations, are predicted to result in large-scale forest tree mortalities worldwide, with cascading impacts on associated communities. At present, however, our understanding of how dependent ecological communities change in response to such events are poorly documented, limiting our understanding of the complex interactions that stabilize community compositions in forests. In Hawaiʻi, two newly discovered fungal pathogens causing widespread mortality of ‘Ōhiʻa lehua (Metrosideros polymorpha), the most ecologically important native tree in Hawaiʻi, pose an immediate and serious threat to the diversity, structure, and function of Hawaiʻi’s remaining native forests and reliant plants and animals. Given the lack of functional redundancy of ‘Ōhiʻa within Hawaiian forests, the widespread or total loss of this foundation species may undermine existing ecological networks and create cascading changes that may result in new ecological communities and relationships. We will use soundscape indices as a measure of biodiversity of audible species to: 1) evaluate how ecological communities change in response to high mortality of ʻŌhiʻa, the most ecologically important native tree in Hawaiʻi, and 2) determine whether the diversity and species composition of understory vegetation influences how ecological communities dependent on ‘Ōhiʻa forests shift in response to structural changes in the forest canopy and/or changes in microclimate. The use of soundscape indices to model biodiversity following the loss of a foundation species represents a novel and relatively rapid method for assessing ecological change and would be applicable in a range of ecosystems outside Hawaiʻi.