HOLOCENE POLLEN DIAGRAM FROM LAKE ANTOINE, GRENADA

Upland vegetation history of the Lesser Antilles Islands is poorly known because there are few lakes – Grenada with late-Pleistocene volcanism is an exception. Lake Antoine (17 ha, 6 m asl) occupies a circular volcanic explosion crater, which is 500 m from the sea; it may have formed when rising seawater encountered hot magma about 14,000 years ago. There is no inlet or outlet. Around the lake margin is marsh of Montrichardia arborescens, Cladium jamaicense, Acrostichum danaeifolium, Eleocharis flavescens and Nymphaea ampla. On the adjacent slope is pasture, sugar cane fields and plantations of coconut, cocoa and banana; the upper slopes support secondary dry forest including Bursera simaruba, Spondias mombin and Pisonia fragrans. Organic sediment fills the lake to 5 -7 m depth. An 850-cm long core of detritus gyttja bottomed on sand. Five calibrated radiocarbon dates and two historic levels permit modeling of sedimentation rate and chronology. Palynological analysis of 66 levels shows four zones. Zone 1 in basal sand is dominated by the brackish water marsh fern Acrosticum. Zone 2 is dominated by pollen of the palm Roystonea oleracea with shrub Triumfetta and the alga Pediastrum argentiniense. Zone 3 begins at 4,300 years B.P with a peak of the disturbance-indicating Cecropia; it generally lacks palm pollen. The enigmatic monolete fern spore, cf. Nephrolepis rivularis is abundant; Bursera, Spondias, Pisonia and cf. Pouteria indicate upland dry forest; relatively abundant Cladium and Nymphaea indicate freshwater marsh. Beginning 300 years ago historic Zone 4 (0-190 cm) features Poaceae and especially Zea and Cocos.