Plantings of Red Mangroves (Rhizophora Mangle L.) for Stabilization of Marl Shorelines in the Florida Keys

摘要

Shoreline stabilization using mangrove plantings offers an environmentally and economically superior alternative to the construction of seawalls, riprap, etc. Three developmental stages of red mangroves (i.e., propagules, seedlings and small trees) were planted to provide erosion protection along three separate sections of marl shoreline at Key West, Florida. Mangrove propagules ('beans') which were carefully removed from mature fruits or collected from shoreline debris exhibited the greatest vertical growth. However, survival of this stage ranged from 86-14% (X = 45%) and was inversely related to the degree of shoreline exposure. Seedlings (approximately 1 year old) did not exhibit a significantly greater survival rate (X = 48%) or vertical growth than propagules. Transplants of small mangrove trees(i.e., approximately 2-3 years old) were highly successful on all three shorelines exhibiting an average survival of 98% after 23 months. Degree of exposure to erosion and/or burial proved more important in determining seedling survival than either of the organic amendments or tidal heights tested. Using a power auger to bore holes and seagrass wrack as mulch proved to be an effective and economical method of planting all three developmental stages of red mangroves along organically deficient marl shorelines. However, marl shorelines exposed to moderate wave, tidal, or wind action are best planted with small mangrove trees to insure transplant survival and erosion protection. (Author)