RAPID: Cascading effects of rapid and widespread mortality of a foundation tree species on animal communities in Hawaii

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Forests cover a third of all land area on Earth, providing numerous ecological, economic, and social benefits. However, forests worldwide are increasingly vulnerable to large-scale tree mortalities as the frequency rises of invasive pest and pathogen outbreaks. The near elimination of dominant tree species such as American chestnut trees in North America and elm trees in Europe and North America, as a result of introduced pathogens, highlights how diseases can fundamentally change the species composition of forests and lead to cascading effects on dependent animal communities. This project will measure how animal communities reliant on native Hawaiian forests change in response to a new fungal disease causing rapid and widespread mortality to the most ecologically important and abundant native tree. This research provides a unique opportunity to measure in real time changes to animal communities as a response to rapid and ongoing tree mortality, whereas most other studies documenting the effects of widespread mortality of tree species provide retroactive data long after declines. In this project researchers will directly involve underrepresented groups including Native Hawaiian and other Pacific Islanders through the direct training of undergraduate students on the research project. This project will also convene educational events throughout Hawaii Island to communicate the research results.Few studies have quantitatively documented how ecological communities in terrestrial ecosystems respond to the large-scale loss of a foundation species that mediates ecosystem processes and creates stable conditions for inhabitant species. Recent changes in forest structure are expanding across the Hawaiian landscape as a result of rapid, disease-induced mortality of ohia lehua (Metrosideros polymorpha), the foundation tree species of Hawaiian forests. The spreading fungal pathogen (Ceratocystis spp.) poses an immediate and serious threat to the diversity, structure, and function of Hawaii's remaining native forests and reliant plants and animals. Using advances in recording technology and soundscape analysis tools developed within the growing field of soundscape ecology, the researchers will rapidly assess changes in the biodiversity of audible birds, insects, and amphibian species in areas with different baselines and rates of change in ohia mortality across the landscape. The researchers will also evaluate whether the diversity and composition of other plant species within the understory mediates how animal communities respond to structural changes in the forest canopy. The simplified island ecosystem in Hawaii allows research to more directly tease apart the interactions that support community composition and function within forest ecosystems, which will have wide application to more complex and diverse systems that are experiencing large-scale forest tree mortality.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.