Woody Debris in the Mangrove Forests of South Florida

• Published in: Biotropica Vol. 37; no. 1; pp. 9 - 15
• Main Authors: Krauss, Ken W., Doyle, Thomas W., Twilley, Robert R., Smith III, Thomas J., Whelan, Kevin R.T., Sullivan, Jason K.
• Format: Journal Article
• Language: English
• Published: 350 Main St , Malden , MA 02148 , USA and PO Box 1354, Garsington Rd , Oxford , OX4 2DQ , UK and PO Box 378 Carlton South , 3053 Victoria , Australia Blackwell Science Inc 01.03.2005; Blackwell Publishing
• Subjects: Avicennia germinans; Cloud forests; Coarse woody debris; disturbance; downed wood; Everglades; Everglades National Park; Forest ecosystems; Forest regeneration; Hurricane Andrew; Hurricanes; Laguncularia racemosa; Mangrove forests; Montane forests; necromass; Rhizophora mangle; Rookery Bay National Estuarine Research Reserve; Ten Thousand Islands National Wildlife Refuge; Trees; Tropical Biology; Wetlands
• ISSN: 0006-3606; 1744-7429
• DOI: 10.1111/j.1744-7429.2005.03058.x

Woody debris is abundant in hurricane-impacted forests. With a major hurricane affecting South Florida mangroves approximately every 20 yr, carbon storage and nutrient retention may be influenced greatly by woody debris dynamics. In addition, woody debris can influence seedling regeneration in mangrove swamps by trapping propagules and enhancing seedling growth potential. Here, we report on line-intercept woody debris surveys conducted in mangrove wetlands of South Florida 9-10 yr after the passage of Hurricane Andrew. The total volume of woody debris for all sites combined was estimated at 67 m³/ha and varied from 13 to 181 m³/ha depending upon differences in forest height, proximity to the storm, and maximum estimated wind velocities. Large volumes of woody debris were found in the eyewall region of the hurricane, with a volume of 132 m³/ha and a projected woody debris biomass of approximately 36 t/ha. Approximately half of the woody debris biomass averaged across all sites was associated as small twigs and branches (fine woody debris), since coarse woody debris >7.5 cm felled during Hurricane Andrew was fairly well decomposed. Much of the small debris is likely to be associated with post-hurricane forest dynamics. Hurricanes are responsible for large amounts of damage to mangrove ecosystems, and components of associated downed wood may provide a relative index of disturbance for mangrove forests. Here, we suggest that a fine:coarse woody debris ratio ≤0.5 is suggestive of a recent disturbance in mangrove wetlands, although additional research is needed to corroborate such findings.