EFFECTS OF NEIGHBORS ON GROWTH AND MORTALITY OF MANGROVE SEEDLINGS INFLORIDA, USA

Changes in height and mortality rates of red mangrove (Rhizophora mang le), black mangrove (Avicennia germinans), and white mangrove (Laguncu laria racemosa) seedlings were measured in three field stands for 45 m onths. Differences between stands and the effects of size and distance of neighboring trees on individual growth rates were examined. Trees in a ditchside stand demonstrated higher growth rates than those near the upland edge, which in turn, grew faster than those in the high mar sh proper. Mortality rates for red, black, and white mangroves were 9. 6%, 4.6%, and 3.2% per year, respectively, whereas height increment ra tes ranged from 28.5-131.3 cm per year. Moderate salinities and lack o f interference from mature trees are considered partially responsible for the relatively low mortality and high growth rates observed. The o nly consistent effects of neighbors on changes in height of subject tr ees were positive. This result is attributed to shared environmental c onditions between neighboring trees.