State of Hawaiʻi taking action to protect lands, native species from persistent drought
December 2, 2023, 1:00 AM HST
Wednesday and Thursday, a Kona Low dumped more than 5 inches of much-needed rain on some parts of the Big Island, which has suffered from drought since early August.
“The rain will help, but it’s too early to know how much improvement in drought monitor categories it will provide at this time,” said senior service hydrologist Kevin Kodama with the National Weather Service forecast office in Honolulu. “We need to wait and see impact reports.”
According to the U.S. Drought Monitor, as of Nov. 28 about 63% of the Big Island was in severe drought and 12% was seeing extreme drought conditions. The other 15% was under moderate drought.
And, according to the most recent drought information statement for the Hawaiian Islands issued Nov. 8 by the National Weather Service’s Honolulu office, below normal precipitation is expected throughout the islands well into 2024 because of the ongoing El Niño that warms the Pacific waters and weakens trade winds. It also affects the Pacific jet stream, which moves more south than normal, creating dryer and warmer than usual weather.
The persistent drought is a concern for the Hawai‘i Department of Land and Natural Resources, which manages and oversees 800,000 acres on the Big Island.
The dry conditions are creating more fuel for wildfires, a major concern for state officials, and putting more stress on already strained native plants and animals.
National Weather Service drought category definitions:
- Abnormally Dry (D0): Going into drought, short-term dryness slowing planting, growth of crops and pastures; fire risk above average. Coming out of drought, some lingering water deficits, pastures or crops not fully recovered.
- Moderate Drought (D1): Some damage to crops, pastures, fire risk high; streams, reservoirs or wells low, some water shortage developing or imminent, voluntary water use restrictions requested.
- Severe Drought (D2): Crop or pasture loss likely, fire risk very high, water shortages common, water restrictions imposed.
- Extreme Drought (D3): Major crop/pasture losses, extreme fire danger, widespread water shortages or restrictions.
- Exceptional Drought (D4): Exceptional and widespread crop and pasture losses, exceptional fire risk, shortages of water in reservoirs, streams and wells causing water emergencies.
Emma Yuen, native ecosystem program manager for the state Division of Forestry and Wildlife, said the state is seeing the most severe drought on the Big Island in lands along the North Kohala and Kaʻū coasts and leeward areas of Maunakea, specifically in the Pōhakuloa region.
“In these locations, the drought is causing vegetation to become much more prone to wildfires,” Yuen said. “These areas are largely infested with invasive grasses — particularly fountain grass — which can provide fuels to spread wildfires. The less moisture, the quicker and more intensely these wildfires will burn and spread.”
Before humans arrived in Hawai’i, wildfires were not common. If they did happen, they were likely caused by volcanic eruptions or ignited by lightning. Human activity has made the blazes more common and climate change is increasing their risk.
Native Hawaiian plant species have not evolved to be resilient to fire. So when wildfires burn down a native forest or destroy other native plants, invasive plants that quickly recolonize after fires are most likely to take their place.
“This is particularly concerning because the invasive plants are often grasses that have high fuel loads and are able to ignite more readily than the original native forest would,” Yuen said. “Thus, they create a cycle where fires actually make an area more likely to burn in the future.”
The locations seeing some of the worst drought on the island are home to rare plants and animals, all of which have evolved to survive in specific climates and habitats. When the climate changes, they can adapt, but only gradually through generations.
Even those already trying to colonize other areas face challenges because of development or other human-caused disturbances.
More than half of Hawai‘i’s native forests have disappeared, Yuen said, and the remainder are threatened by hooved animals, invasive plants and wildfires. Drought only exacerbates the problems.
Located on the west-facing slope of Maunakea is the only remaining wild population of palila, a critically endangered species of Hawaiian honeycreeper. For food, the birds rely on the seed pods of māmane, a species of flowering plant in the pea and bean family that also is endemic to Hawai‘i.
Drought can cause māmane to stop producing seeds and eventually die, in turn threatening the life of the birds that feed on those seeds.
ʻŌhiʻa, a native Hawaiian tree that provides habitat for many insects and birds, is also under particular threat from extremely dry conditions, especially because of rapid ʻōhiʻa death, a fungus that has killed more than a million of the trees on the Big Island alone.
Drought can stunt and kill ʻōhiʻa seedlings, which are vulnerable to dry conditions, as they try to recolonize decimated forests or other areas. It also can force feral hooved animals such as goats and sheep to migrate to new areas or move deeper into native forests to forage, causing additional damage.
The animals are known to strip bark from trees for food and moisture during severe drought, which is bad for ʻōhiʻa because those wounds make the trees more susceptible to rapid ʻōhiʻa death infection.
Another main concern of state forestry and wildlife officials is a reduction in fresh water supplies.
“Many areas across the state have very limited water available already,” Yuen said. “When there are periods of little rainfall, communities often use more water because they begin to irrigate their lands.”
Native Hawaiian forests, especially rain forests, act like living sponges on the mountains, collecting moisture from rain and passing clouds. That replenishes supplies of underground fresh water. Yuen said protecting native forests dramatically helps relieve the damaging effects of drought.
She said the state and its conservation partners are taking many actions to mitigate the impacts of drought, the first of which is improving overall forest health to increase resilience to drought and other stressors.
The state is protecting native forests by constructing fences around tracts of native habitat to keep out feral hooved animals and removing invasive weeds.
Drought can cause rare native plant species to decline to the point immediate action is needed to prevent their extinction. That can include taking cuttings or collecting seeds to propagate in nurseries in case the wild population disappears.
The Department of Land and Natural Resources also monitors, plans and regulates fresh water supplies.
When it comes to wildfires, the state is working to prevent them and be better prepared to fight the blazes when they start. Yuen said that involves creating firebreaks in areas prone to fire, establishing water sources for fighting the blazes and educating communities about how to stop wildfires from igniting.
The Hawai‘i Department of Transportation has been clearing dry vegetation along roadways in parts of the state to mitigate fire risk.
The state Legislature also formed a Wildfire Prevention Working Group in reaction to the Aug. 8 wildfires on Maui that destroyed Lāhainā and killed at least 100 people. It issued a draft report Nov. 1 and will issue a final report Dec. 15, in time to draft legislation for the upcoming 2024 legislative session that starts Jan. 17.
To learn more about the state’s strategies for drought management, find the most recent Hawai‘i Drought Plan online.