A kīpuka is an area of land that is surrounded by younger lava flows, in effect an "island" within a sea of lava. Literally translated, the Hawaiian word signifies a variation, or change of form. It is one of the few Hawaiian words, like pāhoehoe and ʻa‘ā, to be adopted into the broader vocabulary of geology.
This proverbial oasis can occur when toes of a lava flow split and later reunite downhill, perhaps due to elevated hills or ridges that lava does not flow over. Because they are made of older lava, these "islands" may have significantly more mature vegetation.
Ecologically, kīpuka are important for several reasons. The forests within kīpuka serve as refuges for species of plants and animals. Kīpuka can then act as jumping off points for the later recolonization of the newer lava flows nearby. They also may shelter native species from recently invasive ones. Surrounded by harsh terrain, native plants and animals may be inaccessible to new species that would displace them.
Perhaps most significantly, there are evolutionary consequences to this phenomenon. Because of their isolation, kīpuka foster speciation— the formation of new and distinct species. Once a kīpuka forms, plants and animals that cannot travel long distances on their own become trapped. Organisms within the isolated kīpuka then have a limited gene pool. And over time, without a larger population to breed with, different genes may become dominant. Organisms can evolve significantly— possibly into entirely new species.
This represents in microcosm the evolutionary history of the Hawaiian islands themselves. As the world's most isolated island chain, plants or animals that by happenstance arrived here began to develop in new and different ways. Over thousands of years, species developed in Hawaiʻi that exist nowhere else on the globe.
Within the park, notable kīpuka include Kīpukapuaulu and Kīpuka Kī off of Mauna Loa Road, as well as Kīpuka Nēnē, located along Hilina Pali Road.