Rare plants rebound in newly fenced Ka`u preserve

If you fence it, will things come back?

The Nature Conservancy is reporting resounding—one might say rebounding—success at its Kaiholena Preserve at Ka`u on Hawai'i.

“It’s amazing to see the abundance of new plant life. Plants that haven’t been seen in years are popping up all over the preserve,” said Shalan Crysdale, the Conservancy’s natural resources manager at the preserve.

A six-mile, six-foot-high fence protecting 1,200 acres was completed in 2007. The last of the pigs inside the lowland forest area were removed two years ago. The fence also keeps out Mouflon sheep. And the results are heartening.

The most impressive of the returning wild plants is a native vine, the nuku `i'iwi, whose name reflects the similarity in shape and color between its blossoms and the orange beak of the native red `i`iwi bird. An image of the blossom is shown here, courtesy of The Nature Conservancy.

It's a gorgeous blossoming display, and rare, except in fairly pristine native forest.

The evidence indicates that if you don't wait too long to protect native ecosystems, they can heal.

“The resurgence in plant life is a standard response of our native forest to protection from browsing animals. If there isn’t a major weed problem, the natives often come roaring back,” said Sam Gon, the Conservancy's cultural adviser and senior scientist.

Crews walk the fence perimeter weekly to ensure pigs haven't burrowed under it, and falling trees haven't compromised it. John Repogle, a senior member of the Conservancy's Ka`u field crew, said the fence-walkers can see the improvement in environment inside the enclosure.

“Over time, as we do our fence checks, we have seen dramatic changes in the number of rare native seedlings popping up. I would not have thought pigs had such a destructive effect on these particular plants until I saw how many are now germinating and growing to maturity.

“There is moss on the ground now where it was just soil before. When you look along the fence, the ground level on the outside is three to four inches lower than inside the fence. This is erosion caused by the presence of pigs.”

Among the returning wildlife are lobelias: two species of koli‘i (Trematolobelia wimmeri and Trematolobelia grandifolia) and three species of ‘ōhā wai, including one named for Mauna Loa (Clermontia montis-loa).

© Jan TenBruggencate 2010