HISTORY OF TERRESTRIAL VASCULAR PLANTS 



25 



Woodbury (1962) gathered ecological data on the atoll 

 for the University of Utah from February to May 1962. 

 His report includes very general descriptions of the vegeta- 

 tion on the various islands at that time. 



In 1964, the Laboratory of Radiation Biology of the 

 University of Washington conducted a radiological resurvey 

 of Bikini and Enewetak Atolls (Welander et al., 1966). 

 This report includes many photographs and descriptions of 

 the vegetation on various islands, including notes on vege- 

 tation recovery since the nuclear test days. Observations 

 on vegetation have also been recorded in reports of studies 

 on terrestrial radioisotope cycling (Jackson and Carpenter, 

 1967; Koranda et al., 1978), rats (Jackson, 1969; Fall et 

 al., 1971), and birds (Carpenter et al., 1968). 



The Atomic Energy Commission conducted another 

 radiological survey of the biota and environment of 

 Enewetak in 1972 and 1973. The three-volume report 

 includes color aerial photographs of each of the islands, as 

 well as radiological data on the water, sediments, soil, and 

 biota. Terrestrial biota is reported by Koranda et al. 

 (1973). 



By 1975, the vegetation was gradually recovering on 

 all of the islands and was growing over the remains of 

 buildings and equipment left from the war and nuclear test 

 days. Many of the plants which dominated the vegetation 

 on the islands were introduced weeds, and a few ornamen- 

 tal and crop plants were growing in private gardens. A 

 photographic field guide to plants observed on the atoll 

 from 1975 to 1977 has been compiled (Lamberson, 

 1982). 



In July 1975, a 12-acre plot of land was cleared on 

 Enjebi for an experimental garden project to monitor the 

 uptake of radionuclides from the soil into food plants. This 

 long-term study is supported by the Department of Energy 

 and is contracted to the Lawrence Livermore Laboratory 

 (LLL) of Livermore, Calif. Radiologically "clean" soil from 

 Jedrol was moved to Enjebi in 1975 for control studies. 

 Breadfruit, pandanus, coconut, banana, sweet potato, lime, 

 watermelon, and papaya were planted. 



On September 16, 1976, legal control of Enewetak 

 Atoll was formally transferred from the U. S. government 

 back to the people of Enewetak, with the agreement that 

 radioactive debris and soil and nonradioactive scrap would 

 be removed from inhabitable islands. In late 1976, federal 

 funds were approved for the cleanup, and in 1977 the 

 project was well under way. Some of the people of 

 Enewetak returned from Ujelang Atoll to live on Japtan in 

 March 1977. The program of rehabilitation and resettle- 

 ment of the people included building of houses on 

 Enewetak, Medren, and Japtan and replanting of coconut, 

 banana, breadfruit, pandanus, and other crop plants. 



The effect of the cleanup on the vegetation of radiolog- 

 ically contaminated islands has been very significant. 

 Radioactive soil and debris were removed from many of 

 the northern islands and deposited in a crater on Runit, 

 which will be a permanently radiologically quarantined 

 island. Reconstruction of housing on Enewetak and Lojwa 

 to support cleanup personnel resulted in fairly extensive 



clearing of the vegetation, and the rehabilitation program 

 involved extensive clearing and replanting of crops and 

 food trees on the southeast islands from Ananij to 

 Enewetak. Homes were built for the returning people of 

 Enewetak on the islands of Japtan, Medren, and Enewetak, 

 and the people returned to the atoll between 1977 and 

 1979. The radiological cleanup and the rehabilitation pro- 

 grams were completed in 1980, but it will be years before 

 the atoll again supports mature groves of coconut, bread- 

 fruit, and pandanus. 



SUCCESSION AND OBSERVATION, 

 1975 TO 1977 



After nuclear testing ceased at Enewetak Atoll in 

 1958, the vegetation was relatively undisturbed for almost 

 20 years, permitting the observation of plant distribution 

 and succession under "natural," if unusual, conditions. The 

 scrap and radiological cleanup operations beginning in 

 1977 and the rehabilitation and replanting for the return of 

 the people of Enewetak have resulted in large-scale altera- 

 tions to the vegetation. It seems appropriate, therefore, to 

 report on the condition of the vegetation before the 

 cleanup, 1975 to 1977. 



Plant succession on the leeward islands, Ikuren through 

 Biken, was followed through literature reports, aerial pho- 

 tographs, personal communication, and observation. For 

 convenience, several stages of succession were defined. 



Stage 1, early pioneers, was seen on sand bars, spits, 

 and small islands that were subject to storm damage and 

 washover. Plants had to survive harsh conditions of intense 

 sun, drying winds, and salt spray. They also had to over- 

 come high salt concentration in the sand and the lack of 

 water and nutrients. This stage was seen on narrow 

 portions of Ikuren; on the small island between Elle and 

 Bokenelab; on Bokinwotme; and on the small islands of 

 Boko, Munjor, and Jinedrol. Plant genera present were 

 Tournefortia, Scaeuola. Lepturus. and Triumfetta and see- 

 dlings of Guettarda. Mohnda, Suriana, and Cocos (Fig. 1). 



As these plants become established, there is more pro- 

 tection from wind and sun, and organic matter accumulates 

 in the soil to provide nutrients and to hold moisture. 



In Stage II, a thick scrub growth of mixed genera 

 occurs, impenetrable without a sharp machete and pa- 

 tience. This stage was seen on the eastern ends of Ikuren, 

 the southeast end of Boken (Irwin), and on Bokandretok 

 and formed the beach vegetation on many of the islands. It 

 forms a protective barrier against salt spray and allows for 

 development of vegetation inland on the larger islands. In 

 addition to genera found in Stage I, vines such as 

 Ipomoea, Canavalia, and Cassi/tha are present. Terminalia, 

 Cordia. Pemphis, and Pandanus may also appear, and 

 ground plants such as Lepturus and Triumfetta are con- 

 fined to the margins (Fig. 2). 



In Stage 111, the soil is more fertile, the trees are larger, 

 and birds nesting in the branches add to the soil nutrients 

 with their droppings and an occasional regurgitated fish. 

 An open grassland develops under the trees, and ground 



