Ka’ala Blues

By Kat Fitzpatrick
O’ahu, Hawaii

Atop Mount Ka’ala, on O’ahu’s highest peak, blue moss turns the native forest’s understory into a palette of aquamarines and teals so vivid and otherworldly, it resembles an undersea paradise. But don’t break out your scuba gear. It’s an illusion.


Photo: Kim Welch

This phenomenon, as brilliant as it is, is unfortunately the result of a life-and-death battle happening 4,000 feet above sea level. It’s the all-too-common environmental bugaboo of an introduced species taking over the ecosystem of a native plant.

First documented on O‘ahu in the late 1960s, this seemingly harmless, feathery little moss (I know, how threatening can a moss be, right?) has been on track to choke out the resident moss on the summit of Ka‘ala on O’ahu’s west side. The plant is known to be one of the fastest growing Sphagnum mosses (Sphagnum palustre) in the world, and it’s executing its evil plan at an alarming rate.

A steep hike from Waianae Valley along the Kamalleunu Ridge Trail leads to the top of Mount Ka'ala. (Photo: Leonard S. Jacobs / flickr)

A steep hike from Waianae Valley along the Kamalleunu Ridge Trail leads to the top of Mount Ka’ala. (Photo: Leonard S. Jacobs / flickr)

Researchers believe the invasive moss was tracked in by hikers, though this has never been confirmed. In 1997, the moss was observed covering just a six-foot swath on the peak. Now, it covers upwards of 1.25 hectares. This menace has increased in area by more than 900 percent over the last 16 years. It deserves the true-blue treatment it’s getting.

Enter the O’ahu Army Natural Resources Program (OANRP) and the State of Hawaii Natural Area Resource (NARS) Program. In a joint effort, they have discovered a simple mixture of clove oil and citric acid kills off the unwanted intruder while allowing the more timid native moss to survive.

What’s of interest to travelers is the bright blue marker dye environmentalists spray to identify the treated area. For days and weeks afterward, the dye transforms the landscape into a stunning sight. The blue spray, in conjunction with the naturally bright greens and browns of the understory, is so otherworldly, hikers whip out their cameras and might even be tempted to dive in; so great is the sensation you’re traversing an underwater realm. But really, it’s moss. You can’t swim in it.

There are two ways to get there. One way is by driving to the trailhead on O’ahu’s west side, then hiking three and a half miles up a steep and challenging trail along the Kamalleunu Ridge. The other is to sign up as a volunteer and help in the restoration effort. A day of volunteering gets you a ride to the top and entry into the depths of the forest, and lets you be part of a critical effort to save a native old growth forest.

The staff of the Army’s civil service branch make the day pleasant and rewarding. If you have the time, it’s well worth doing.

To find out more about how to volunteer, contact OANRP at or (808) 656-7741.

kat-fitzpatrick-headshot-150Kat Fitzpatrick has lived all over the world but spent the majority of her youth in Hawaii. Her writing career began in 4th grade when she was a prizewinner in an essay contest on Thomas Jefferson. She now resides in Upstate New York.

Published on Tuesday, September 10, 2013

One Response to “Ka’ala Blues”

  1. Kattina
    September 10, 2013 at 3:32 PM

    What a great piece! I am delighted that I get to read your writing!

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