Abstract: The Deering Estate Natural Area (DENA) historically contained a freshwater wetland environment that fed into the Biscayne Bay through the Cutler Creek. Wetland conditions diminished over time as natural sheet flow was interrupted by fragmentation, urbanization, and drainage activities in the Everglades. To restore the authentic watershed of south Florida, the Comprehensive Everglades Restoration Plan’s Biscayne Bay Coastal Wetlands (BBCW) project was developed to divert freshwater from canals into select ecosystems along the southeast coast. The BBCW’s Cutler Slough Rehydration Project (CSRP) facilitates this aim, utilizing DENA land as a funnel to resupply Biscayne Bay with freshwater since December 2012. Since the CSRP’s implementation, upland hardwood hammock and low elevation remnant historical wetland habitats within DENA have been continuously influenced by fluxes of freshwater which affected the health of resident trees. In 2016, I conducted a study of tree dynamics along three transects that cross the CSRP’s watershed. Data collected consisted of tree location, species, health status (live or dead), and diameter-at-breast height. The study revealed that the establishment of hardwood hammock species at low elevations may have resulted from the historical drawdown in the regional water table. Implementation of the CSRP has provided a remedy to that trend, causing substantial mortality among hardwood hammock species in low elevation regions. In 2021, I resurveyed the transects to document the ongoing impact of the rehydration on trees and collected data on the ingrowth of new trees. Continued tree mortality has led to a change in species composition, primarily in low elevation regions of the watershed. As tree mortality progressed after the 2016 study, loss of mature trees allowed for establishment of species more tolerant of seasonal flooding conditions, including Royal Palm (Roystonea regia). In June 2019, my colleagues and I initiated a study of the rehydration efforts water regime, based on 17 Onset HOBO water level data loggers spread along the transects and across DENA. A spatial autocorrelation analysis showed that water levels are less synchronized and uncorrelated to one another the farther away the loggers are from source of freshwater input. Due to the fluctuating water levels, and variable surface topography of DENA, species encounter a wide range of hydrological niches, allowing hydrophytic and mesophytic species to coexist in the same watershed. This integrated monitoring program can provide much insight to where shifts in species composition and species establishment have and will occur through the course of the CSRP.
