Monday, May 27, 2024
Volcano Watch

Forested 'kipuka' are oases of life

The Hawaiian word “kipuka” refers to a variation or a change in form. Forest kipuka are formed when a continuous forested habitat on the slope of an active volcano is covered by a fresh lava flow. Small remnant islands of forest are left behind, in a sea of new lava. Over time, new vegetation grows on these surfaces, and more lava flows inundate the area. The result is a patchwork quilt of lava flows and kipuka of varying maturity.

A mature, closed-canopy Hawaiian forest usually takes 300-3,000 years to develop on new lava flows. Hawaiian Volcano Observatory scientists have calculated that 40 percent of the surface of Mauna Loa is covered by new lava flows every 1,000 years. These figures indicate that a small fraction of forested kipuka on Mauna Loa is likely to reach maturity before being inundated by lava once more. In fact, some of the small kipuka on the northeast flank are thought to be as old as 3,500 years.

A mature kipuka looks like a green oasis in a sea of dark and barren lava. As you approach the kipuka, the trees do not look very tall. Sometimes they stand only 10 or 15 feet above the edge of the `a`a flow you are standing on. Once you reach the edge of the kipuka, however, you see that to get into it, you have to descend from the top of the lava flow, sometimes as much as 5 or 10 feet down, to get to the floor of the forest. The kipuka is like a small time capsule. The floor is covered in lush, green hapu`u fern, while the canopy is dominated by native koa and `ohi`a trees.

In Hawai`i, geology and biodiversity go hand in hand. The formation of new islands has promoted adaptive radiation and creation of new species. On individual islands, such barriers as deep valleys and lava flows have provided an extra level of isolation for populations of animals and plants, which have diversified still further. The forested kipuka work in much the same way, but on a smaller geographical scale.

Recent work undertaken by USGS biologists has shown that populations of some spider species found in these old kipuka show increased genetic diversity between kipuka. They theorize that the shifting mosaic of habitats, formed as forests are destroyed and fragmented, work to create and maintain genetic differences among populations and, ultimately, cause the evolution of new species. In this way, discrete populations of genetically distinct organisms can occur in small areas.

Biologist Vandergast says, “It is like each population in a kipuka is holding a ticket in the evolutionary lottery. Most likely, the genetic changes will be minor, but there is a very slight chance that one of these populations is holding the winning ticket….”

The mature kipuka also provide safe, albeit small, homes for many endangered species today. Endangered honeycreepers, such as the Hawaiian creeper and akiapola`au, are restricted to kipuka in this area (and the slopes of Mauna Kea). For these birds, which are already very rare, lava flows and forest destruction can be a forerunner to extinction. The o`u, a honeycreeper said to be one of the most common of the native Hawaiian birds before 1900, was last seen in 1984 in a kipuka which was overtaken and destroyed by a large `a`a flow from Mauna Loa.

Just as the shifting mosaic is fascinating for biologists and conservationists, it also makes the geologist’s work easier. The flows, older against younger, stand out when their surfaces have been more or less colonized by plants. Hawaiian Volcano Observatory scientists, engaged in detailed mapping of Mauna Loa, have found that surface lava flows in this sector of Mauna Loa range in age from 10,000 to 21 years old. Finding out when the flows were emplaced is sometimes difficult, but this process is occasionally made easier by the presence of charcoal fragments that remain when forests are inundated and destroyed. These fragments can then be radiocarbon-dated, much to the delight of natural scientists.

Activity Update

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater and on the southwest side of the cone.

The PKK lava tube continues to produce intermittent surface flows from above the top of Pulama pali to the ocean. Two ocean entries, at East Lae`apuki and East Kamoamoa, were active as of June 29. Surface flows are active intermittently inland of the entries. The East Lae`apuki entry is the closest to the end of Chain of Craters Road, in Hawai`i Volcanoes National Park. From the ranger shed, it takes about 2 hours to walk the 4.5 km (3 miles) to the entry. Bring lots of water, and stay well back from the sea cliff, regardless of whether there is an active ocean entry or not. Remember—the beaches that sometimes form next to an active bench are just as dangerous as the bench itself. Stay off both, and heed the National Park warning signs.

A breakout on the west side of the PKK flow, which first made it over Paliuli last week, continues to creep across the coastal plain about 3.3 km (2 miles) from the ranger shed. The flow, still about 1 km (0.6 miles) from the ocean, is the closest activity to the ranger shed. It could be difficult to locate, however, so check with the rangers for guidance before making the trip. Expect a 1.5-hour walk each way and, again, remember to bring lots of water.

During the week ending June 28, one earthquake was felt at Hawaiian Ocean View Estates, Hawai`i Island. That earthquake occurred 2 km (1 mile) southeast of Pahala at a depth of 9 km (6 miles) at 4:51 p.m. on Friday, June 24, 2005.

Mauna Loa is not erupting. During the week ending June 28, six earthquakes were recorded beneath the summit area. None of them were deep or long-period in nature. Inflation continues, but at a slightly reduced rate since late April of this year.

This article was written by scientists at the U.S. Geological Survey’s Hawaii Volcano Observatory and is republished by with permission.

Hawaii Star Wire

Press releases, media advisories, and other announcements submitted to the Hawaii Star.

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