Asa McCurdy’s research investigates the role of nonstructural carbohydrates (NSCs) and chemical defenses in ʻōhiʻa trees' resistance to Rapid ʻŌhiʻa Death (ROD). His team combines fieldwork and greenhouse experiments to analyze how energy reserves support defense responses against infection. Recent work includes a full year of tissue sampling from healthy trees, a pilot study testing induced defenses using methyl jasmonate, and chemical profiling that revealed promising links between leaf chemistry and pathogen resistance. The findings may lead to new metrics for identifying resistant ʻōhiʻa and guiding restoration strategies.
The ʻŌhiʻa Disease Resistance Program (ʻŌDRP) continues statewide efforts to identify and propagate ʻōhiʻa trees with natural resistance to Rapid ʻŌhiʻa Death (ROD). In the past year, hundreds of plants representing dozens of genotypes underwent resistance screening, including trials focused on both wild-collected and commercially available stock. The team also revisited mother trees from earlier trials and advanced plans for a 2.5-acre common garden at Keaukaha Military Reserve, where top-performing trees will be outplanted and monitored. These efforts aim to accelerate reforestation with resilient ʻōhiʻa stock across Hawaiʻi.
Solomon Champion’s research focuses on the genetics and hybridization of Hawaiian sandalwoods (ʻiliahi), particularly the threat posed by introduced Indian sandalwood (Santalum album). His work reveals repeated hybridization events throughout the islands, including ongoing introgression that may compromise endemic species. Using tools like scanning electron microscopy and molecular markers, Solomon is helping to clarify the evolutionary history of ʻiliahi and develop protocols to ensure genetic integrity in future restoration and seed orchard efforts.
Pandu Wirabuana’s research explores how planting design influences growth dynamics between ʻiliahi (Santalum paniculatum) and its host plants in Hawaiʻi’s dry forests. Across three integrated studies, his work examines competition, facilitation, and parasitism in mixed stands to identify optimal ʻiliahi-to-host ratios, planting mixtures, and limiting factors. Findings show that ʻiliahi thrives when host abundance is higher, with a 2:1 host-to-ʻiliahi ratio offering the best balance for growth. This work supports more effective reforestation strategies and lays the groundwork for sustainable yield models of hemiparasitic forest species.
Tawn Keeney’s research investigates the physiological mechanisms behind the parasitic relationships of ʻiliahi (Santalum paniculatum) to identify ideal host species for restoration and cultivation. His work explores how factors like host pairing, gene expression, haustoria development, and water potential gradients influence nutrient exchange between ʻiliahi and its hosts. Through three experiments involving gene sequencing, X-ray root imaging, and isotope tracing, Tawn aims to better understand how ʻiliahi interacts with different native species—ultimately improving host selection strategies for forest restoration and sustainable ʻiliahi production in Hawaiʻi.
Erin Bell’s research explores how native birds support forest restoration across Hawaiʻi Island. One study uses remote sensing and bird surveys to evaluate the effects of restoration on avian communities. Another examines how birds disperse seeds in degraded landscapes, informing strategies to accelerate forest recovery. A third focuses on translocated ʻōmaʻo and their role in restoring lost ecological functions. Together, her work contributes to more effective habitat restoration and conservation of Hawaiʻi’s native ecosystems.
Kelly French’s research at Tropical HTIRC investigates how environmental factors influence the growth and survival of Hawaiʻi’s native sandalwood, ʻiliahi (Santalum paniculatum). By establishing a common garden study on Hawaiʻi Island, she’s examining how site-specific conditions like soil nutrients, moisture, and temperature affect seedling performance. Her findings aim to guide restoration efforts by identifying optimal planting sites and improving management practices for native dry forest ecosystems.
Gorse, a hardy shrub, has overwhelmed Mauna Kea's landscape, necessitating creative control methods led by the DHHL and Dr. JB Friday. To increase biodiversity, koa, sugi pine, and redwood trees have been planted post-herbicide and bulldozing in an effort to outcompete the returning gorse. A notable concern is potential frost damage to koa seedlings, as the planting area experiences subfreezing temperatures. To mitigate this, researchers installed temperature sensors to monitor the benefits of gorse rows for insulation. Despite drought risks, over 80% of the koa seedlings planted in May have thrived, offering promising possibilities for future reforestation projects.
Rebekah Ohara’s research explores the emergence and potential of community-based forest management (CBFM) in Hawai‘i. Drawing from case studies across the Pacific and grounded in work with the Kaiāulu Pu‘uwa‘awa‘a Community-Based Subsistence Forest Area, her dissertation identifies key pathways to successful CBFM. Findings emphasize the importance of Indigenous Knowledge, secure land tenure, and collaborative governance in advancing biocultural forest stewardship statewide.
Kylle Roy's research at Tropical HTIRC focuses on understanding how ambrosia beetles spread the Rapid ‘Ōhiʻa Death (ROD) fungal disease, threatening the Hawaiian rainforest. Using chemical ecology, Kylle's goal is to develop early detection tools and strategies to manipulate beetle populations, thereby protecting 'ōhiʻa trees from ROD. Her findings underline the importance of creating beetle management strategies, including the potential use of semiochemical repellents, to curb the spread of this devastating disease.
The ʻŌhiʻa Disease Resistance Program (ʻŌDRP), a collaborative effort involving federal, state, and university entities and led by the Akaka Foundation for Tropical Forests, addresses the widespread Rapid ʻŌhiʻa Death (ROD), a fungal disease that has claimed over a million ʻōhiʻa trees in Hawaiʻi since 2010. Discovering certain ʻōhiʻa genotypes with natural resistance to ROD, the initiative now aims to aid forest restoration by supporting private landowners and conservation managers in propagating these resilient plants.
Tawn Speetjens evaluated fertilizer and hosting treatments required to grow healthy ‘iliahi seedlings in the nursery and what types of hosting schemes are necessary to maximize ‘iliahi seedling survival when planting in in barren monotypic pasture landscapes.
Solomon Champion, a PhD candidate at the University of Hawai‘i at Mānoa, is conducting a detailed genetic study of native Hawaiian sandalwood (Santalum L.) to understand gene flow and relatedness among various species and populations, some of which may be threatened by hybridization. The research focuses on fifteen identified populations of Santalum paniculatum, using samples from wild populations and nurseries, and supplements its analysis with additional samples from the Hawaiian Plant DNA Library.
Approximately 16 sandalwood species (Santalum spp.) occur worldwide and at least four sandalwood species and several varieties are native to the Hawaiian Islands, where it is known as ‘iliahi. ʻIliahi is economically and culturally important because of the heartwood’s aromatic essential oil and high value wood for carving. During the early 19th Century, Hawaiian sandalwood was heavily exploited until supplies were depleted. Two species are now relatively common, including S. paniculatum, which is the only species commercially harvested on a limited scale; however, the species have not regained their former abundance or size.
