Responses of Four Non-tidal Forest Communities of the Florida Everglades to Hurricane Impact over 21 Years

Abstract

The regular occurrence of hurricane-associated winds has been an important factor in shaping the structure and composition of the forest ecosystems of the Florida Everglades. Forest communities in the Everglades are adapted to hurricane disturbances, but increased frequency and/or intensity of hurricanes may lead to decline or even collapse of these communities. The overall objective of this project is to understand the patterns, pace, and mechanisms of the recovery process to Hurricane Andrew damage in four Everglade forest communities: pinelands, hardwood hammocks, bayhead tree islands, and cypress domes. This study combines long-and short-term field measurements and experimental garden studies to determine how the four woody plant community types recover from hurricane impacts. Most of the community types were adversely affected by storm damage in the short-term (3 years post-hurricane) through altered growth rates and canopy defoliation, however these effects were relatively short vii lived and were not visible in shifts in species composition after the long-term (20 year) recovery period. Only in the most diverse communities over the long-term there was a delayed mortality in damaged individuals that drove a diversity loss. This loss was not present over the short-term recovery time period. Using individual damage extent and short-term recovery growth rates, I developed a simplified model that accurately predicted surviving individual stem size over long-term recovery periods of Taxodium distichum within cypress domes and select hardwood hammock species. The shadehouse experiments demonstrated the importance of nutrient availability to growth of seedlings of canopy dominants. Recruits of these species responded to changing environmental conditions associated with storm impact through a variety of strategies in accordance with their adaptive traits. Synergistically, the combined parts of this dissertation demonstrate directional community and species-specific shifts that vary over time scales.Storm impacts have the potential to alter community composition and diversity within impacted systems, and in particular the Everglades ecosystem.viii Taxodium distichum dominate cypress dome communities because they are able to establish in and tolerate long hydroperiods that exclude other woody species (Duever et al. 1986).Cypress dome communities are dominated by a single species (Taxodium distichum var. nutans) and are relatively resistant to the damaging effects of hurricanes, with mortality of damaged trees being relatively low , Noel et al. 1995.Non-canopy species such as epiphytes are shown to be highly damaged from hurricanes but their communities recover (Oberbauer et al. 1996). Large trees are more likely to be damaged as a result of storm impacts. (Whelan 1997). Toppling of tall trees in cypress domes can be beneficial to the community because it allows for regeneration of the canopy by new recruits (Duever et al. 1986).Pineland communities in the Everglades are dominated by a single species (Pinus elliott...

Hurricane Michael Altered the Structure and Function of Longleaf Pine Woodlands

“…In most other studies, however, there was a lack of baseline information prior to the storm (Hogan et al., 2020). Even though valuable insight on damage can still be gained, assessing if an ecosystem has returned to pre‐storm function is challenging (May, 2016). As a forest recovers, the rate of canopy development and resource availability will affect the system's future carbon dynamics (Gavito et al., 2018; Vargas & Allen, 2008; Yamanoi et al., 2015).…”