Broadleaved forests

Littoral Forest

Found along sandy or rocky shores on the high islands and inland on larger, wetter atolls, this vegetation type includes familiar coastal species seen elsewhere in the Pacific. Fronted by shrubby Scaevola taccada, sometimes with Sophora tomentosa and Tournefortia argentea, or on rocky coasts by Pemphis acidula, the woody species in this community include Calophyllum inophyllum, Casuarina equisetifolia, Cordia subcordata, Ficus spp., Guettarda speciosa, Hernandia nymphaeifolia, Hibiscus tiliaceus, Morinda citrifolia, Neisosperma oppositifolia, Pandanus spp., Pisonia grandis, Premna serratifolia and Terminalia catappa. Much of the former habitat of littoral forest has been converted to agro-forestry, and the best remaining examples are found on uninhabited islands or on sandy or limestone coasts.

On Tobi and Fana in the Palau Outliers, a mixed forest occurs inland of the strand vegetation. The main tree species on Tobi are Artocarpus mariannensis, Calophyllum inophyllum, Ficus prolixa, Neisosperma oppositifolia, Pipturus argenteus and Premna serratifolia, along with the less common Guettarda speciosa, Hernandia nymphaeifolia and Syzygium malaccense. On Fana, the forest includes Ficus senfftiana, Neisosperma, Pandanus spp., Pipturus spp. and individuals of Pisonia grandis and Ficus prolixa.

On Fana, the centre of the small island is filled with a 10-hectare pure stand of Pisonia grandis up to 22 m tall.

Mangrove Forest

Found along the lower portions of rivers and on coastal mudflats, the mangrove forests in Palau are the most species-rich in Micronesia. Well-developed stands can become 15 to 20 m tall. On the seaward side, Rhizophora stylosa and Sonneratia alba dominate; at larger river mouths or bay indentations, Rhizophora apiculata and R. stylosa can become pure stands or occur with Sonneratia alba and Bruguiera gymnorrhiza; landward, Heritiera littoralis, Lumnitzera littorea and Xylocarpus granatum are included in the mix; and where the estuary becomes river-like, Bruguiera, Lumnitzera, Sonneratia and Xylocarpus species are common, but Rhizophora spp. becomes uncommon. The palm Nypa fruticans is fairly common along the lower portions and mouths of rivers. Other woody species include Avicennia marina, Ceriops tagal and Scyphiphora hydrophyllacea.

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Swamp Forest

Often found just inland of mangrove forest, where the soils are inundated with fresh or slightly brackish water, coastal swamp forests in Palau are today generally degraded and covered with Hibiscus tiliaceus; other suitable habitat has been replaced by taro cultivation. Tree species include Barringtonia racemosa, Calophyllum soulattri, Cynometra ramiflora, Heritiera littoralis, Horsfieldia irya, Samadera indica and Terminalia catappa.

Interior Upland Forest

On the volcanic high islands, large portions of the hilly interior are vegetated by a species-rich mixed broadleaf forest that occupies flat or gently sloping sites as well as river and stream banks. One of the most common tree species is Campnosperma brevipetiolata. Other tree species include Alphitonia carolinensis, Calophyllum inophyllum var. wakamatsui, C. pelewense, C. soulattri, Cerbera floribunda, Fagraea ksid, Glochidion macrosepalum, G. ramiflorum, Horsfieldia irya, H. palauensis, Htuberculata, Manilkara udoido, Myristica insularis, Maranthes corymbosa, Atuna racemosa, Serianthes kanehirae and Symplocos racemosa var. palauensis. Along ravines and streams, Barringtonia racemosa and Semecarpus venenosus are common, and the palm Pinanga insignis is occasionally seen.

Limestone Forest

South of Oreor, islands in the group are composed of sharply eroded limestone with little soil cover. These habitats are covered with a closed, diverse, broadleaved, generally low-statured forest that was once more widespread, but was greatly disturbed during World War II. Woody species include Aidia racemosa, Badusa palauensis, Cycas circinalis, Cyrtandra todaiensis, Eugenia reinwardtiana, Flacourtia rukam var. micronesica, Garcinia matudai, G. rumiyo var. calcicola, Geniostoma sessile, Guettarda speciosa, Gulubia palauensis, Intsia bijuga, Ixora casei, Meryta senfftiana, Morinda latibracteata, Polyscias grandifolia, Premna serratifolia, Psychotria hombroniana, Rinorea bengalensis and Tarenna sambucina. The endemic Gulubia palauensis palm was once very common in these limestone islands and was a common canopy emergent, but has been decimated by the predations of introduced parrots and has its last haven in Chelbacheb.

last updated: Monday, January 12, 2004