Landscape patterns of community structure, biomass and net primary productivity of mangrove forests in the Florida Coastal Everglades as a function of resource, regulators, hydroperiod, and hurricane distrubance

Abstract

Spatial and temporal patterns of mangrove vegetation in the Florida Coastal Everglades (FCE) reflect a major interplay of resources, regulators and hydroperiod gradients. I investigated landscape patterns of community structure, biomass and NPP of mangroves along two FCE estuaries: Shark River and Taylor River. I also evaluated whether pulsing events such as Hurricane Wilma are significant to soil nutrient inventories and vertical accretion of mangroves in FCE. There was a higher forest structural complexity of mangroves in Shark River relative to Taylor River. The biomass root:shoot ratio was 17 times higher in Taylor River relative to Shark River, indicating that scrub mangroves allocate a larger proportion of their total biomass to belowground. Root turnover rates consistently decreased as the root size classes increased from fine to coarse roots, indicating differences in longevity. Fine root biomass was negatively correlated with soil P density and frequency of inundation. Average total NPP was twice in Shark River compared to Taylor River. Aboveground production accounted for 68% (Shark River) and 42% (Taylor River) of the total NPP. Total root production contributed 32% (Shark River) and 58% (Taylor River) of the total. Sediment deposition from Wilma decreased with distance inland at each site. Vertical accretion resulting from this hurricane was one order of magnitude greater than the long-term accretion rate. Total P inputs from hurricane sediments were equivalent to twice the average soil P density (0.19 mg cm-3). Results from this study indicate that scrub mangroves of Taylor River have adapted to P limitation and flooded hydroperiods by allocating more biomass and production belowground relative to aboveground. Allochthonous mineral inputs from Hurricane Wilma represent a significant source of sediment to vertical accretion rates and nutrient resources in mangroves of southwestern Everglades. This source of P is significant to forest development due to the P-limited condition of this carbonate ecosystem. This information on how mangrove biomass and NPP are distinctly allocated between above- and belowground in response to environmental gradients across the FCE will be used to develop carbon budgets before and after hurricanes and to improve our understanding of carbon dynamics in neotropical mangrove forests.