Two UH Hilo graduate students present their research at the 4th International Congress on Biological Invasions hosted in Aotearoa New Zealand
Olivia Jarvis and Nai‘a Odachi are investigating the use of satellite imagery to map the spread of two major invasive species in Hawai‘i’s native forests. The goal is produce data of use to policymakers as the state faces climate change and other stressors.
By Susan Enright.
Two graduate students from the University of Hawai‘i at Hilo presented their research at the 4th International Congress on Biological Invasions hosted in Ōtautahi Christchurch, Aotearoa New Zealand, May 1-4, 2023.
Olivia Jarvis and Nai‘a Odachi, in the UH Hilo tropical conservation biology and environmental science graduate program, joined other scientists from around the world who gathered to share new findings on invasive alien species and their impact on biodiversity, ecological systems, and food production. Both budding researchers are investigating the use of satellite imagery to map the spread of invasive species in Hawai‘i’s native forests. For Jarvis, it’s strawberry guava pushing out native trees, and for Odachi, it’s the fungus that causes Rapid ‘Ōhi‘a Death which is killing—at an alarming rate—a culturally and environmentally important tree in Hawai‘i. More about the students’ research further on in this story.
But first, some information about the grad students’ mentor, Ryan Perroy, professor of geography at UH Hilo who specializes in aerial imagery of vast and remote native forests suffering from Rapid ‘Ōhi‘a Death. Perroy accompanied the two students to Aotearoa.
Professor Perroy is principal investigator at the UH Hilo Spatial Data Analysis and Visualization laboratory (SDAV), a research unit applying geospatial tools to local environmental problems in Hawai‘i and the Pacific region and where both Jarvis and Odachi are basing their research.
Learn more about Professor Perroy’s research:
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- Researchers design more effective aerial device to collect Rapid ‘Ōhi‘a Death samples (UH Hilo Stories, Oct 6, 2022)
- Environmental scientists show link between rapid ‘ōhi‘a death mortality levels and hoofed mammals (UH Hilo Stories, Aug. 9, 2021)
Perroy gave an oral presentation at the conference, “Hawaiian forest mortality trajectories associated with Ceratocystis wilt of ‘ōhi‘a,” as part of a Ceratocystis and Rapid ‘Ōhi‘a Death session that included multiple representatives and researchers from Hawai‘i. Their research suggests “a primary initial site-level infection event, potentially related to intense storm activity, followed by secondary spread of the disease via other mechanisms. The duration of symptomatic stages following infection is inversely related to relative humidity, which is relevant for detection and monitoring efforts. Ungulate presence plays an important role in disease incidence, with significant reductions in ‘ōhi‘a mortality evident within fenced (ungulate-free) areas,” according to a summary of the presentation.
About the trip and the two students’ participation, Professor Perroy says, “It was a great experience for everyone and an excellent conference.”
Olivia Jarvis: Strawberry guava
Jarvis graduated in 2018 from El Camino High School in Oceanside, CA, and received her bachelor of science in environmental science from UH Hilo in 2022 with subject certificates in data science, the Marine Option Program, and Spanish language for careers. She is a student-athlete, where she’s been on the women’s cross country roster since 2018, and delivered the keynote at the recent Student-Athlete Academic Honors Reception.
In the UH Hilo tropical conservation biology and environmental science graduate program, Jarvis is working on her master’s thesis proposal about strawberry guava trees. “Strawberry guava is an invasive species that forms dense thickets that can invade ‘ōhi‘a forest habitat,” she explains.
Jarvis’s poster presentation, entitled, “Strawberry guava (Psidium cattleianum) detection from satellite imagery using machine learning and species distribution modeling on Hawai‘i Island,” shows her research into where the species is today and where it could spread under various climate change conditions.
“Strawberry guava (Psidium cattleianum) trees have invaded tropical forests and degraded native ecosystems around the world,” Jarvis explains in the summary of her presentation. “Because populations are dense and widespread, field crews are unable to accurately survey all current locations of strawberry guava.”
This is where remote sensing technologies come in, expanding the scope of spatial scale where invasive species can be detected. “This project aims to use satellite imagery and supervised machine learning methods, such as random forests and convolutional neural networks, to identify strawberry guava trees on Hawai‘i Island and map their present distributions,” says Jarvis.
“The goal of this work is to gain an understanding of where the species is today, and where it could spread under various climate change conditions, to provide insight to where land management efforts should be focused on to reduce the spread of this tree and restore native forests,” she says.
Nai‘a Odachi: Rapid ‘Ōhi‘a Death
Odachi graduated high school in 2016 from Hawai‘i Academy of Arts and Sciences in Pāhoa, Hawai‘i Island, and in 2019 received bachelor of arts degrees in both art and geography from UH Hilo. Now a graduate student in UH Hilo’s tropical conservation biology and environmental sciences program, she is researching the use of satellite imagery to survey native forests for Rapid ‘Ōhi‘a Death.
‘Ōhi‘a trees are ecologically and culturally essential for Hawai‘i, but since 2014 when it was first discovered, Rapid ‘Ōhi‘a Death, or ROD, has killed hundreds of thousands of mature ‘ōhi‘a trees (Metrosideros polymorpha) throughout the Hawaiian Islands. It is caused by two invasive fungi, Ceratocystis huliohia and Ceratocystis lukuohia, and has the potential to irreversibly change some native Hawaiian ecosystems.
Odachi’s poster presentation at the Aotearoa conference, entitled, “A comparative analysis of monitoring methods for Rapid ‘Ōhi‘a Death in Hawai‘i: high-resolution satellite imagery and digital mobile sketch mapping surveys,” focused on work she’s done to identify active red crown ROD mortality in high-resolution satellite imagery on an annual basis starting in 2013. She compared her findings to existing helicopter-based surveys that have been conducted biannually beginning in 2016.
“Ongoing monitoring of Hawai‘i’s forests is necessary to identify new ROD outbreaks and may also provide insight for directing management efforts,” she says. “High-resolution satellite imagery expands upon the existing monitoring efforts which are spatially limited. Using this [satellite] imagery can reduce the need for helicopter based surveys, which are time-consuming, dangerous for aerial surveyors, and produce significant carbon emissions.”
The conference experience
Both Odachi and Jarvis were thrilled to present their findings at the conference and to meet fellow researchers and learn about their work.
“Being able to present at an international conference was an incredible opportunity that allowed me to share the work our lab does with a larger audience,” says Odachi. “Additionally, it was amazing to hear about ongoing research that scientists are conducting, not only in the United States but also in other countries.”
She credits the opportunity and sends a big thank you to Professor Perroy, “who continuously supports my research and pushes me toward new opportunities.”
Jarvis says presenting a poster at the conference was an amazing experience.
“I had the opportunity to have interesting conversations and make some meaningful connections with scientists from around the world,” she says. “I learned a lot from talks on invasive species work from other countries and found a small community of scientists there interested in how to use machine learning and species distribution modelling to answer questions about alien plant species and climate change, similar to my project.”
Jarvis says she’s only at the beginning stages of her master’s thesis project, but attending, learning, and meeting people at this conference motivates her to keep going, “and gives me good things to think about as I continue to work on the project this summer.”
She also sends credit and a big thank you to Professor Perroy “for giving me the opportunity to present at this conference.”
Support
Jarvis’s funding for the trip came from the Hawai‘i Data Science Institute and through Perroy’s SDAV lab. She also received support through the National Science Foundation (NSF Award No. 2118222, CyberTraining: Implementation: Medium: Cyberinfrastructure Training to Advance Environmental Science). Among other goals, this NSF funding, through UH Mānoa, is being used across the UH System to create workshops and curriculum for undergraduate and graduate students to increase cyberinfrastructure (CI) skills across environmental science fields. By providing the next generation of environmental scientists and practitioners with advanced CI skills, these future professionals will have the ability to use CI to transform science in the region across academic research institutions, public agencies, and community stakeholders.
Conference fees and accommodations for Odachi were covered by The New Zealand Institute for Plant and Food Research. Her trip was also supported by the Hawai‘i Department of Land and Natural Resources and funding through the SDAV lab. DLNR also provided funding for Perroy to attend the conference.
Story by Susan Enright, a public information specialist for the Office of the Chancellor and editor of UH Hilo Stories. She received her bachelor of arts in English and certificate in women’s studies from UH Hilo.
