Hurricane disturbance and recovery of energy balance, CO2 fluxes and canopy structure in a mangrove forest of the Florida Everglades

Abstract

"Hurricane disturbance and recovery of energy balance, CO 2 fluxes and canopy structure in a mangrove forest of the Florida Everglades" (2012). USGS . http://digitalcommons.unl.edu/usgsstaffpub/911 Agricultural and Forest Meteorology 153 (2012) [54][55][56][57][58][59][60][61][62][63][64][65][66] Contents lists available at ScienceDirect Agricultural and Forest Meteorology j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / a g r f o r m e t Hurricane disturbance and recovery of energy balance, CO 2 fluxes and canopy structure in a mangrove forest of the Florida Everglades At the EC site, high winds from the hurricane caused nearly 100% defoliation in the upper canopy and widespread tree mortality. Soil temperatures down to −50 cm increased, and air temperature lapse rates within the forest canopy switched from statically stable to statically unstable conditions following the disturbance. Unstable conditions allowed more efficient transport of water vapor and CO 2 from the surface up to the upper canopy layer. Significant increases in latent heat fluxes (LE) and nighttime net ecosystem exchange (NEE) were also observed and sensible heat fluxes (H) as a proportion of net radiation decreased significantly in response to the disturbance. Many of these impacts persisted through much of the study period through 2009. However, local albedo and MODIS (Moderate Resolution Imaging Spectro-radiometer) data (the Enhanced Vegetation Index) indicated a substantial proportion of active leaf area recovered before the EC measurements began 1 year after the storm. Observed changes in the vertical distribution and the degree of clumping in newly emerged leaves may have affected the energy balance. Direct comparisons of daytime NEE values from before the storm and after our measurements resumed did not show substantial or consistent differences that could be attributed to the disturbance. Regression analyses on seasonal time scales were required to differentiate the storm's impact on monthly average daytime NEE from the changes caused by interannual variability in other environmental drivers. The effects of the storm were apparent on annual time scales, and CO 2 uptake remained approximately 250 g C m −2 yr −1 lower in 2009 compared to the average annual values measured in [2004][2005]. Dry season CO 2 uptake was relatively more affected by the disturbance than wet season values. Complex leaf regeneration dynamics on damaged trees during ecosystem recovery are hypothesized to lead to the variable dry versus wet season impacts on daytime NEE. In contrast, nighttime CO 2 release (i.e., nighttime respiration) was consistently and significantly greater, possibly as a result of the enhanced decomposition of litter and coarse woody debris generated by the storm, and this effect was most apparent in the wet seasons compared to the dry seasons. The largest pre-and post-storm differences in NEE coincided roughly with the delayed peak in cumulative mortality of stems in [2007][2008]. Across the hurricane-impact...

Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands

“…These correlations indicate that transpiration is a larger portion of evapotranspiration at forested wetlands with larger and more densely spaced cypress and pine trees. Closed or partially closed forested canopies reduced the penetration of solar radiation to water surfaces, creating low- ered lapse rates between the water surface and canopy crown (Barr et al, 2012), and they added resistance to evaporation. Collectively, these results indicate that a redistribution of plant communities toward more open-water ecosystems (such as sparse sawgrass) could result in less C uptake and greater evaporative losses.…”

“…Lowered salinities, resulting from increased freshwater flow, resulted in increased daily PAR-use efficiency (i.e., the ratio of gross ecosystem productivity to photosynthetically active irradiance (PAR; Barr et al, 2010Barr et al, , 2012). Also, ecosystem respiration losses were lower during periods of inundation (Barr et al, 2010(Barr et al, , 2012, which increased net C uptake over the mangrove forest. These studies provide insights into water and C cycling over coastal sawgrass wetlands and mangrove forests.…”

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“…Another method of estimating forest lateral carbon export utilizes the difference between measurements of net ecosystem-atmosphere CO 2 exchange (NEE) above the mangrove forest surrounding Shark River (267 ± 15 mmol m −2 yr −1 in 2004; (Barr et al, 2012) (Breithaupt et al, 2014) measured at the same location (FCE LTER site SRS6) in this forest. The difference between NEE and NECB (40 ± 17 mmol m −2 d −1 ) provides an estimate of the annual rate of forest carbon export to Shark River on a daily basis (Chapin et al, 2006).…”

Turning the Tide: How Blue Carbon and Payments for Ecosystem Services (PES) Might Help Save Mangrove Forests

“…; Piou et al 2006). Following Hurricane Wilma in 2005, mangrove sites in the Florida Everglades took 2-4 years to approximate pre-disturbance levels of albedo, CO 2 net fluxes, and soil elevation (Barr et al 2012). …”