During the subsurface investigation of the Easy and X-Ray ground zero sites in August and September 1978, several samples of asphalt were taken. The asphalt was found 20 to 80em below the surface, in layers 2 to 10em thick. Soil samples from above and below the asphalt layer were also taken, and both the soil and asphalt analyzed for gamma activity. The shallowersoil samples and the top of the asphalt were both relatively "cleaner" than the deeper soil and the bottom of the asphalt. Although the source of the asphalt was not known at the time, it was assumed to be part of the material said to have been buried in the X-Ray crater after that event. The information about activity on the asphalt was used to help guide the remainder of the subsurface investigations of the Easy and X-Raysites. Samples of surface concrete were taken in mid-September 1978, from Greenhouse Station 3.1.1, a multistory structure near the center of Janet. The samples were analyzed for gamma activity to provide JTG with information necessary to plan for proper disposal of the debris when the structure was demolished. No significant quantities of 24lam, 137¢s or 60Co were found on any of the samples. After the Janet cleanup was complete, scientists from Lawrence Livermore Laboratory began a study in April 1979 of 37Cs movement in soil at a site near PORKY. A 100x 100-m area was denuded of vegetation, and the IMP took measurements at 10m spacing to establish the baseline activity. The plan was to keep the area free of vegetation to determine if the rate of 1375 movement out of the root zone was significantly altered in the cleared area. The study is still in progress as of June 1980. 6.5 VEGETATION (by Bert Friesen, H&N) Vegetation in the Atoll Environment ro: 6.5.1 Vegetation on the islands of Enewetak Atoll is typically a mixture of trees, shrubs, suffrutescent perennials, strand plants, clumpy grasses and sedges. Vegetation cover ranges from impenetrably dense brush to open meadow-like areas of grasses and sedges. The two most common species of brush are the small tree, Tournefortia argentea L. f. and the large shrub, Scaevola taccada (Gaertn.) Roxb. Both are evergreen and grow to an average height of 12 to 15 feet. Tournefortia grows from a single trunk and spreads readily by the dispersal of seeds. Scaevola lacks a trunk and arises from a number of decumbent or ascending main branches. The species grows readily from seed and also reproduces vegetatively by rooting at the nodes of the lower branches where they come in contact with the ground. New leaves are initiated on both plants only at the ends of the branchlets and the mature foliage on the lower portions of the branches is not replaced when it dies. The result is a thin canopy of leaves covering a tangle of bare branches with a thick layer of decomposing leaves beneath. No other vegetation appears to grow under well-established thickets of Tournefortia or Seaevola. (Tournefortia is a recently-assigned name to replace Messerschmidia, but this is not common knowledge, so the more commonly known name is used elsewhere in this report.) Oeeasional stands of Pisonia grandis R. Br., Pluchea indica (L.) Less, Pluchea_symphytiftolia (Mill) groves of coconut on Nancy and Vera. By April 1980, the coconut grove on Vera and the Pisonia groves on Olive and Tilda had been cleared away and new coconut trees planted as part of the rehabilitation following cleanup. The predominant vines observed on Enewetak are two species of Feanees (Morning glorys) including I, macrantha R. & S. and I. pes-caprae (L.) Sweet ssp. brasiliensis (L.} v. Ooststr. Also occurring are the viny, suffrutescent perrenial, Triumfetta procumbens Forst, f., and several species of trailing, perennial herbs including Boerhavia tetrandra Forst., B. albiflora Fosberg var. powelliae Fosberg and B. repens L. The morning glory U. pes-caprae ssp. brasiliensis) is typically the first ground cover to recolonize disturbed areas, followed by Fimbristylis atollensis St. John and a mixture of native and exotic grasses. In describing the ecological succession that occurred on Enewetak after the nuclear testing program, the role of the morning glory was stated (Woodbury, 1962) as follows: 163 a7 Gillis, Morinda citrifolia L. var. citrifolia and Guettarda speciosa L. appear in minor quantity. Very few Pandanus sp. and Cocos nucifera L. were observed prior to cleanup, with the exception of the