A natural treasure — including one of the wettest spots on Earth — is now protected as Hawaii's third-largest private nature preserve under an agreement brokered by The Nature Conservancy.

The Conservancy and private landowner Alexander & Baldwin (A&B) announced in November that a 7,050-acre parcel owned by A&B on the Hawaiian island of Kaua'i will be managed over the next decade as the Conservancy’s newest Hawai‘i preserve. The preserve includes Kauai's remote Wainiha Valley and portions of the Alaka‘i wilderness and Mount Wai‘ale‘ale, which receives about 460 inches of rain per year.

Amazing Biodiversity Threatened by Invasives

Scientists have long acclaimed the region encompassed by the new preserve as a gem of Hawaiian biodiversity. Its sheer, rain-carved cliffs, valley and summit plateau — so remote that they can only be accessed by helicopter — are a haven for rare plants and birds, seven of which are on the federal endangered species list.

But Wainiha's native flora and fauna are now threatened by invasive weeds and animals such as wild pigs and goats. The agreement ensures that the Conservancy will partner to fight these invasives.

“Wainiha is a place of incredible natural beauty and a treasure chest of Hawaii’s native plants and animals,” says Suzanne Case, the Conservancy’s Hawai’i executive director. “It’s been our highest priority for conservation for many years. Now, thanks to Alexander & Baldwin, we will be able to protect it.”

A Global Treasure

Kauai’s age, isolation and topography have made it the most biologically diverse of the main Hawaiian islands — home to more than 400 endemic species of flowering plants and animals, or species found only in Hawai‘i.

The Garden Isle has almost half of Hawaii’s endemic flowering plants and natural communities, and more than half of its native bird species.

“Because it’s the oldest and most isolated of the main islands, many of those species are found only on Kaua‘i,” said Trae Menard, director of the Conservancy’s Kaua‘i field office.

“When you talk about sites of global biological importance, you include places that have high species diversity and high endemism," adds Menard. "And Kaua‘i has both.”  

Examples of this astonishing diversity include:

• Native lowland forest, which is hardly found elsewhere in the islands;
• A globally rare Hawaiian freshwater stream community;
• A native mint — Phyllostegia helleri — previously thought to be extinct in the wild at Hinalele Falls;
• One of the largest populations of the rare fern Microsorum spectrum, the fragrant laua‘e fern famous in Kaua‘i chant and traditions;
• Rare and endangered native forest birds such as the ‘akikiki, or Kaua‘i creeper, ‘akeke‘e, ‘apapane, ‘amakihi and ‘elepaio; and
• The endangered Hawaiian seabird ‘ua‘u (Hawaiian petrel), which has valuable nesting sites on a wet cliff ecosystem that separates the valley from the Alaka'I Plateau.

About 1,300 acres of the new preserve encompess the Alaka'i, a mile-high plateau cradled between the mountains that is Kauai’s greatest biological treasure. A wilderness of rare plants and birds, the 12,000-acre plateau sits on the flank of Mt. Wai‘ale‘ale and at the head of Kauai’s five largest aquifers.

Not only is the area the island’s primary source of water, but its native ecosystems include rare mountain bogs and the islands’ most diverse high-elevation rain forest. Within the A&B portion of the Alaka‘i, there are 131 plant species found only in Hawai‘i, 46 of which are found only on Kaua‘i. 

Tackling Threats Together

The new preserve lies at the core of the 157,000-acre Kaua‘i Watershed Alliance management area. Management actions aimed at controlling weeds and feral pigs and goats in the parcel are an integral part of a larger Alliance effort to protect the island’s priority watershed forest.

Menard said that fast-spreading weeds and animals threaten the fragile balance of Wainiha’s native ecosystems. Invasive weeds such as Australian tree fern and Clidemia, commonly called soapbush or Koster's curse, are already moving up the valley, as are wild pigs.

“Australian tree fern is the biggest threat. And it’s urgent, because right now we have a narrow window of opportunity to try to get in there and control it,” Menard said.

“Clidemia is the other big weed problem. But if we’re able to build a fence to keep the pigs from moving up the valley, and reduce disturbance to the forest, we can slow the advance of the Clidemia down to a manageable level.”

The Conservancy and the Kaua'i Watershed Alliance have begun implementing protective measures to halt the spread of invasive species. Menard stressed that a coordinated approach is critical in effectively addressing present and future threats.

With the 10-year agreement in place, the Conservancy can now better integrate its conservation work with the Alliance's watershed management program and protect the heart of Kauai’s native Hawaiian forest.

Confidence in The Conservancy's Capabilities

The new Wainiha Preserve encompasses about 5,750 acres of Wainiha Valley and nearly 1,300 acres of the Alaka‘i plateau and Mount Wai‘ale‘ale summit region. The parcel is part of about 10,000 acres owned by A&B in the Wainiha Valley area.

“A&B has been a dedicated steward of these Kaua‘i lands for well over a century, and over time, our awareness has sharpened about the tremendous biological importance of this valley, and the imminent threats to the habitat,” says A&B Chairman and CEO Allen Doane.

“Our company has confidence in The Nature Conservancy’s capabilities and we are pleased to partner with them to pursue our common goal of ensuring the protection of this valuable natural resource for generations to come.”

Nature picture credits (top to bottom, left to right): © John De Mello/TNC (aerial view of Wainiha Valley, Hinalele Falls); © Nicolai Barca/Jonathan Faford/TNC (Alaka'i wilderness); © Ken Wood/National Tropical Botanical Garden (Phyllostegia helleri); © Trae Menard/TNC (invasive Australian tree fern).