Maui Department of Water Supply Koa and ʻŌhiʻa Projects
Over more than a century of socioeconomic transformation, Hawaiʻi’s watersheds have been heavily degraded due to increased wildfires, underinvestment in natural resource protection, and invasive species of weeds, mammals, pathogens, and insects. The impacts of ecosystem loss are biological, with >75% of Hawaiian birds and >30% of native plants listed as endangered, and social, with irreplaceable losses to Hawaiian culture due to species extinctions, decreases in groundwater recharge, and increased vulnerability to flooding, fires, and nearshore pollution.
Ecological restoration, planting native trees and understory plants, helps reverse ecosystem degradation by controlling threats to promote natural regeneration and rebuilding native ecosystems. This requires collecting and storing native seeds, developing seed orchards, growing seedlings in nurseries, and transplanting seedlings to restoration sites. Restoring native ecosystems will combat climate change, enhance watershed function, and reduce wildfire risk. However, according to the National Academies of Sciences, Engineering, and Medicine (2023), “the insufficient supply of seeds from native plants is a major barrier to ecological restoration… across the US.” This is especially true in Hawaiʻi, where native seeds are hand collected from wild populations—according to a 2016 Hawai’i Seed Bank Partnership survey, seed availability is a major limiting factor to the diversity of plants used in restoration. Addressing this requires scaling native seed and seedling production, especially keystone forest trees like Koa and ʻŌhiʻa.
Without disease-resistant koa and ʻōhiʻa seed, many Maui landowners will remain unable to efficiently utilize koa in many of their watershed restoration efforts. In response to this, HARC has worked with the Department of Water Supply (DWS) since 2012 to develop a network of sites on Maui to establish wilt resistant koa seed orchards in multiple eco-regions. These are located at Haleakala Ranch, Kula Forest Reserve, and Ulupalakua Ranch, in priority watersheds on the windward and leeward flanks of Haleakala Crater. The investment the DWS has made in native forest tree seed production is now paying dividends. The older koa orchards continue to yield seed crops. Substantial amounts of seed are available of locally adapted, wilt resistant koa seed. With seed inventories building, landscape level restoration projects are now possible, and the ability to respond to natural disasters such as hurricanes and wildfires is greatly improved. Recent DWS support has enabled this program to expand and begin the process of developing ʻōhiʻa seed orchards for resistance to the fungal disease Rapid ʻŌhiʻa Death (ROD).
Maui County now has the capability to plant locally adapted, disease resistant koa, which when reintroduced at a landscape level will directly benefit the long-term sustainability of Maui County’s water supply in high priority watersheds. Native forests are more efficient in water use and more effective than exotic trees in recharging aquifers and help improve water infiltration rates. By developing wilt resistant koa and ROD-resistant ʻōhiʻa, restored forests, watersheds, and Hawaiʻi’s communities will have increased health and resilience.
HAWAII AGRICULTURE RESEARCH CENTER
Maui Department of Water Supply Koa and ʻŌhiʻa Projects
Over more than a century of socioeconomic transformation, Hawaiʻi’s watersheds have been heavily degraded due to increased wildfires, underinvestment in natural resource protection, and invasive species of weeds, mammals, pathogens, and insects. The impacts of ecosystem loss are biological, with >75% of Hawaiian birds and >30% of native plants listed as endangered, and social, with irreplaceable losses to Hawaiian culture due to species extinctions, decreases in groundwater recharge, and increased vulnerability to flooding, fires, and nearshore pollution.
Ecological restoration, planting native trees and understory plants, helps reverse ecosystem degradation by controlling threats to promote natural regeneration and rebuilding native ecosystems. This requires collecting and storing native seeds, developing seed orchards, growing seedlings in nurseries, and transplanting seedlings to restoration sites. Restoring native ecosystems will combat climate change, enhance watershed function, and reduce wildfire risk. However, according to the National Academies of Sciences, Engineering, and Medicine (2023), “the insufficient supply of seeds from native plants is a major barrier to ecological restoration… across the US.” This is especially true in Hawaiʻi, where native seeds are hand collected from wild populations—according to a 2016 Hawai’i Seed Bank Partnership survey, seed availability is a major limiting factor to the diversity of plants used in restoration. Addressing this requires scaling native seed and seedling production, especially keystone forest trees like Koa and ʻŌhiʻa.
Without disease-resistant koa and ʻōhiʻa seed, many Maui landowners will remain unable to efficiently utilize koa in many of their watershed restoration efforts. In response to this, HARC has worked with the Department of Water Supply (DWS) since 2012 to develop a network of sites on Maui to establish wilt resistant koa seed orchards in multiple eco-regions. These are located at Haleakala Ranch, Kula Forest Reserve, and Ulupalakua Ranch, in priority watersheds on the windward and leeward flanks of Haleakala Crater. The investment the DWS has made in native forest tree seed production is now paying dividends. The older koa orchards continue to yield seed crops. Substantial amounts of seed are available of locally adapted, wilt resistant koa seed. With seed inventories building, landscape level restoration projects are now possible, and the ability to respond to natural disasters such as hurricanes and wildfires is greatly improved. Recent DWS support has enabled this program to expand and begin the process of developing ʻōhiʻa seed orchards for resistance to the fungal disease Rapid ʻŌhiʻa Death (ROD).
Maui County now has the capability to plant locally adapted, disease resistant koa, which when reintroduced at a landscape level will directly benefit the long-term sustainability of Maui County’s water supply in high priority watersheds. Native forests are more efficient in water use and more effective than exotic trees in recharging aquifers and help improve water infiltration rates. By developing wilt resistant koa and ROD-resistant ʻōhiʻa, restored forests, watersheds, and Hawaiʻi’s communities will have increased health and resilience.