Species-Area Relationships on Small Islands: Floristic Data from Belizean Sand Cays

Abstract

Analysis of species records of plants from 34 sand cays on the barrier reef and atolls of Belize, Central Amerca, shows a linear relationship between species number and the logarithm of island area over the range 0.13 ha to 16.50 ha. Shrubs and trees show only a slight increase in numbers with area, because of the small number of shrubs available to colonize available habitats and the clearing of native woodland for coconut plantations. Herb numbers increase more strongly with island area, probably as a result of disturbance of habitats by man. Distance from source areas forms a much weaker control of species numbers, because of the proximity of the cays to Central America and their equal distance from eastern Caribbean source areas. Comparison with other island groups, however, shows that the Belize cays have much larger floras than more remote oceanic islands of similar sizes. Limited inferences on colonization and extinction can be made from the species records.