The island of O'ahu (see map) is the second oldest of the islands that make up the main Hawaiian chain and has rugged relief brought about by over 2 million years of exposure to the forces of weather and waves. Scattered across the mid to high elevations of the island--and often quite visible as landscape features--are tree plantations that were established beginning around 1900. Several years ago, Dr. Deborah Woodcock, from the Geography Department at the University of Hawai'i at Manoa, became interested in these plantations and began taking students out on field trips to look at some of the over 800 tree plantations that can be found on O'ahu (see photo below). The more they looked, the more interesting these features seemed and the more questions arose. Why, for instance, were the trees planted to begin with? What tree species were planted and why? How have the plantations affected the physical environment? And, most importantly, what has been the effect of the plantations on Hawai'i’s native plants and animals?
Some of these questions could be addressed by fieldwork but some required study of planting records and other historical sources. Little by little, the story of tree planting in Hawai‘i began to emerge. Like much else in Hawai’i, it is a story that is unique to the islands, starting with the reasons that the plantations were first established. The goal was not to produce timber; instead, the motivation for planting trees was to reforest the upper slopes of the islands, especially the higher elevations that serve as recharge areas for the islands’ aquifers (which supplied water for irrigation of sugar cane). Thus the plantations, which were never intended for timber harvest, still persist today.
Another unusual characteristic about plantation forestry in Hawai‘i is the great number of tree species that were planted, many on an experimental basis. In most places in the world, generally only a few species are utilized in commercial forestry. In Hawai‘i, more than 800 species were planted, including trees from almost everywhere in the world (photo at right is Eleocarpus grandis, an Australian tree with prominent buttresses that are common in rain forest trees in many parts of the world but absent in native Hawaiian forests). Because of Hawaii’s warm climate and favorable growing conditions, many of these trees grew well. Many also became naturalized, producing viable offspring and establishing permanent populations. Native species were not planted very extensively, and early foresters had a variety of reasons that they thought native species undesirable or unsuitable. If Hawai‘i were anywhere else in the tropics, the introduction of so many alien tree species would be a significant problem. Instead, because of the fragility of Hawaii’s biota, the large number of plants and animals found nowhere else in the world, and the vulnerability of small island populations to extinction, the introduction of so many species is an environmental disaster. Naturalized plantation trees have added to an alien-species problem that is the worst in the world.
The early foresters thought they were following best scientific management practices. We now know better, and have to see Hawaiian forestry as yet another lesson in the unintended environmental consequences that so often follow from human actions.
For more information on this topic, look for Dr. Woodcock’s forthcoming article: Woodcock, D.W. To restore the watersheds: Early 20th century tree planting in Hawai‘i. Annals of the Association of American Geographers.
Why is the introduction of so many exotic species considered an environmental disaster for Hawaiian ecosystems? (Use the chapters on Ecosystems and Biomes for information and ideas to answer this, or check out this site).
To create paragraphs in your essay response, type <p> at the beginning of the paragraph, and </p> at the end.
