Effects of neighbors on growth and mortality of mangrove seedlings in Florida, U.S.A.

Abstract

Changes in height and mortality rates of red mangrove (Rhizophora mangle), black mangrove (Avicennia germinans), and white mangrove (Laguncularia racemosa) seedlings were measured in three field stands for 45 months. Differences between stands and the effects of size and distance of neighboring trees on individual growth rates were examined. Trees in a ditechside stand demonstrated higher growth rates than those near the upland edge, which in turn, grew faster than those in the high marsh proper. Mortality rates for red, black, and white mangroves were 9.6%, 4.6%, and 3.2% per year, respectively, whereas height increment rates ranged from 28.5–131.3 cm per year. Moderate salinities and lack of interference from mature trees are considered partially responsible for the relatively low mortality and high growth rates observed. The only consistent effects of neighborns on changes in height of subject trees were positive. This result is attributed to shared environmental conditions between neighboring trees.