Vegetation and Urbanization on Majuro Atoll, Marshall Islands!

The urban and nonurban vegetation on the Micronesian atoll of Majuro is described, including changes in forest canopy, understory shrubs, yards, and cultural features since urbanization began in 1944. Currently, the nonurban areas are covered with Cocos nucifera (coconut) groves mixed with smaller Artocarpus altilis (breadfruit) groves, which were probably established in the late 1800s. Indigenous vegetation is limited to a narrow band along the ocean or lagoon shoreline, or as minor understory species in the CocosArtocarpus groves. A United States military base was established in 1944 on three eastern islands of the atoll (Uliga, Dalap, and Djarrit). This has subsequently been developed into a major administrative and commercial center for the Marshall Islands. Urbanization on Uliga, Dalap, and Djarrit has resulted in reduction of tree canopy; establishment of extensive yards with grasses, herbs, and sedges; and reduction of many indigenous and aboriginally introduced understory species. Nevertheless, some aboriginally introduced and indigenous species remain in the urban areas as important species (Cocos, Artocarpus, and Tournefortia), with many being actively propagated. Ornamental species, which have expanded in importance, especially in the shrub layer, consist primarily of species recorded in Laura village prior to urbanization. The urban plant community is a mixture of indigenous, aboriginally introduced, and recently introduced species. Future urban expansion is predicted with commercial and residential development replacing horticultural forests along the southern islands of the atoll. MAN HAS AFFECTED the distribution and abundance of plant species on the Pacific islands from the earliest contacts, but urbanization is a relatively recent and infrequent occurrence (Fosberg 1963). Although urban ecosystems are expanding units, descriptions and ecological investigations of their unique biological communities are rare (Schmid 1975). The current report describes the urban and nonurban vegetation of a Pacific atoll undergoing rapid change since 1944. The extensive alteration and manipulation of plant communities by indigenous agriculturalists on Pacific atolls has been commented upon frequently (Bates and Abbott 1958, Niering 1963). On the atolls, the indigenous vascular flora is limited, with for example, I Manuscript accepted 19 July 1977. 2 School of Australian Environmental Studies, Griffith University, Nathan, 4111, Australia. 41 species on Kapingamarangi (Niering 1963) and 44 on Arno (Hatheway 1953). The arrival of ocean-going cultures began a process of plant introduction that significantly increased the vascular flora of most islands. For example, aboriginal introductions brought 16 species tb' :Kapingamarangi (Niering 1963) and 24 species to Arno (Hatheway 1953). The atoll agriculturalists have removed or reduced the indigenous plant communities, replacing them with communities dominated by useful species. Only the driest atolls have escaped major vegetation changes (Fosberg 1956). Trading and missionary influence began in the 1800s followed by military operations in the 1900s imposing further changes on the atoll ecosystems. In the early 1900s the commercial and administrative centers of European and Japanese interests became established on various islets of the atolls. With the onset of World War II, Japanese