Although reef flats are typically wider wherever an islet 

 turns sharply, it is not unexpected that these perimeter bands 

 are the most extensive on the extremely exposed shores of 

 northern Nake( PI. 17)andsouthernSouthIsland. On the latter, 

 they are up to 59 m wide. Similarly, on small exposed motus 

 (e.g.. Skull. Noddy Rock), they carpet most of the area 

 (Fig. 27). Under such conditions, Portulaca and Boerhavia 

 develop much redder stems, possibly due to the presence of a 

 chemical "sunscreen." 



Associations with Birds : Whether bordering the edges of 

 established islands or composing the entire ground cover of 

 tiny motus and ancient reef channels, herb mats are nesting 

 sites for red-tailed tropicbirds, masked and brown boobies, 

 sooty terns, and brown noddies. Herb mats are often used as 

 foraging grounds for shorebirds. 



Beach Scrub with Sunana ( 1 .49 ha) (Fig. 20; Pis. 6,24,39,44) 

 Uncommon on Caroline, beach scrub with Suriana is 

 typically foundon sandorsandy rubble bordering Tournefortia 

 or Cocos. On Caroline, it is evidently limited by the paucity of 

 low-lying sand and gravel sheets, with which it is normally 

 associated elsewhere (Fosberg, 1953; Wiens, 1962;Stoddart& 

 Gibbs, 1975). 



The following species are present (see Table 2 for 

 abundance indices): 



Shrubs: Tournefortia argentea, Suriana maritima; and 

 Herbs: Heliotropium anomalum, Boerhavia repens, 

 Portulaca lutea, Laportca ruderalis, Phymatosorus 

 scolopendria, and Lepturus repens. 



This plant community was found on 10 motus (Fig. 20), 

 either in thick bands or as scattered shrubs. Suriana is most 

 robust on sandy substrates, especially fringing the lower lagoon 

 on South Island (Fig. 36; Pis. 6,24,39) and on windward 

 Tridacna. The fringe, repeatedly interrupted by other species, 

 grows to 1 2 m wide and 1.8 m high. Here the shrubs are closely 

 appressed and slightly entangled, forming dense shade, which 

 supports a sparse understory. On South, where its roots are 

 submerged at high tide, it is being shaded out by overhanging 

 Cocos (compare Pis. 39 and 40), having retreated since 1965. 

 Suriana also occurs as scattered individuals or in open bands in 

 coarse rubble. Beach strand up to 60 m wide, containing herb 

 mats, Tournefortia, and scattered Suriana, were found on 

 South (Tr. 1, PI. 21 ). Long (Tr. C), Brothers. Matawa, Long, 

 and the Southern Leeward Islets. 



Pandanus Forest (3.38 ha [this figure is pure Pandanus forest. 

 Mixed forests containing Pandanus account for a further 

 14.96 ha]) (Fig. 11; Pis. 18.35-38) 



Although several species of Pandanus are native to the 

 Line Islands, and their seeds are common components of 

 Pacific sea-drift (Ridley, 1930; Stone, 1968), it is probable that 

 the groves of P. tectohus on Caroline represent both naturally 

 established forests and cultivars transported by early 

 Polynesians. Its largest acreages are on two islands that 

 contained historical settlements (Nake, South). However, its 

 presence within the interior forests of a few motus lead us to 

 conclude that it may have experienced a dual introduction. On 

 Emerald Isle, 3.20 ha (38% of the islet) supports a mixed forest 



of Tournefortia, Pisonia, and Pandanus. Similarly, Shark 

 Islet's interior woodlands of Tournefortia, Pisonia, and Cordia 

 (5.52 ha, 70% of the islet's area) also contain a substantial 

 amount of Pandanus. The only record of habitation for these 

 motus was a possible hut on Shark. The occurrence of Pandanus 

 groves or lone trees on other islets (Fig. 1 1 ) is easily attributable 

 to drift seedlings. Dried Pandanus seedpods are the most 

 conspicuous litter along Caroline's lagoon beaches (PL 38); its 

 seeds last for months in seawater (Guppy, 1906) and are 

 probably distributed locally by rats and land crabs, as noted 

 elsewhere (Ridley, 1930). Carpels from Nake's southern 

 mixed woodlands undoubtedly established the grove on 

 Pandanus Islet. 



The mixed forest with Pandanus on south Nake (with 

 Cocos, Cordia, Pisonia, and Tournefortia) contains up to 50% 

 Pandanus attaining heights of 1 2 m (Fig. 37). It does, however, 

 look disturbed. 



Many Pandanus trees were felled on South Island during 

 the coconut planting era (ca. 1 873- 1 925 ), as we know that they 

 were "somewhat numerous" in 1834(Bennett, 1840), but only 

 "one or more of the screw pines were found growing in various 

 parts of the island" in 1883 (Trelease. 1884). A drawing in this 

 latter paper (PI. 50) depicts a grove from South Island denser 

 than any remaining today, where Pandanus is uncommon in 

 the beach scrub bordering the Cocos plantation. 



Trees were fruiting abundantly in September 1988, 

 especially on Nake. The green phalanges, 17.5-20 cm in 

 diameter, ripen to yellow and orange when they fall to the 

 ground. They are eaten by hermit crabs (Coenobita perlatus 

 [PI. 381). 



Tournefortia Scrub and Forest (125.25 ha) (Figs. 24.34; 

 Pis. 5.8,20,30,47.51) 



General Distribution : Characteristic of many Pacific 

 islands, Tournefortia, a broadleafed evergreen, dominates the 

 wooded motus of Caroline, forming 40% of its total vegetative 

 cover (Fig. 24). Its pale foliage and hemispherical canopies (to 

 14 m tall) typically surround the taller, darker canopies of 

 Pisonia and Cordia. 



A hardy halophyte. Tournefortia occurs on every motu 

 and in every habitat except pure Pisonia forest. It is tallest, 

 widest, and lushest on the windward motus, particularly on 

 those where Pisonia is also best developed. Without direct sun 

 though, as under dense Pisonia or Cocos, it withers (PI. 24). 



On other atolls Tournefortia forms a narrow or interrupted 

 belt inland of the beach or is a component of mixed scrub 

 (Fosberg, 1953). However, given the floristic poverty on 

 Caroline, especially of shrubs and trees, Tournefortia not only 

 has expanded into niches that might elsewhere be occupied by 

 combinations of Scaevola. Pemphis, Suriana. Terminalia, 

 Hernandia, Thespesia, Hibiscus, et cetera, but frequently occurs 

 in pure stands ( 1 13.03 ha) that extend well inland. It thus 

 occupies a much higher percentage of the islet areas on Caroline 

 than on atolls with greater biodiversity. For example, Nake, the 

 largest islet, has the greatest amount of Tournefortia (79.68 ha) 

 of any islet: 28.9 ha of pure scrub and forest, 18.28 ha of 

 "savannah," 17.48 ha with Cordia, 8.99 ha with Pisonia, and 

 6.03 ha mixed with Cocos, Pandanus, and Pisonia. 



27 



