Restoration & Monitoring Projects

2006-Present — Plant performances and hydrologic setting in the LILA tree islands:
Many different tree species dominate the vegetation on tree islands in the Everglades and there is evidence that their distribution on a given island is correlated with elevation, via its interaction with hydrology. The Loxahatchee Impoundment Landscape Assessment (LILA) site, with its controlled hydrologic framework, provides an excellent opportunity to investigate processes involved in the development of tree islands. An experiment was therefore designed to test hydrological and substrate effects on seedling growth and survivorship, and to determine the long term effects of tree spacing on individual tree and stand growth. Four small-enclosed marsh areas, called “macrocosms” (M1-4), form the main structure of the LILA site. Two islands – a peat and a limestone core island representing two major types found in the Everglades – were constructed in each macrocosm. The plantable area of each tree island was divided into four quadrants planted at different, randomly assigned densities, with trees arranged on centers spaced 1, 1.66, 2.33, and 3 m apart. In each quadrant, areas of high and low ground area were delineated, and eight species common to Everglades tree islands were randomly assigned to planting locations within each elevation category. Tree islands in M1 and M4 were planted in March 2006, followed by M2 and M3 islands in March 2007. Survival and height growth of all seedlings were assessed at 2-mo intervals during the first year after planting, every 6 months until 2011 and annually thereafter. The first published results 2.5 years after planting showed that survival and growth improved with increasing elevation on both tree island substrate types. Seedling survival and growth responses along a moisture gradient matched species distributions along natural hydrological gradients in the Everglades. The effect of substrate type on seedling performance showed higher survival of most species on the limestone tree islands, and faster growth on their peat-based counterparts. Based on subsequent analyses, these early responses continued through five years after planting. The effect of spacing was considered to be negligible in the first years of stand development but was expected to play an important role later as competition for light and nutrients intensified, especially at high tree densities. Analyses of spacing effects were initiated in 2009, and several species showed an increasing effect of neighbors on tree growth during the next three years.

2007-Present — FIU Preserve:
We are currently in the planning stages of establishing ongoing FIU South Florida Ecosystem Preserve studies. The broad goals of these studies/experiments are to restore historic conditions and reestablish native species. A large shadehouse is currently under construction adjacent to the preserve site, which will be used in preserve-related experiments. 

2004-Present — MAP—marl prairie-slough gradients:
 The Comprehensive Everglades Restoration Plan (CERP) Monitoring and Assessment Plan (MAP) establishes a framework for measuring and understanding system responses to CERP, to determine how well CERP is meeting its goals and objectives, and to identify opportunities for improving the performance of CERP where needed. Sampling along marl prairie-slough gradients is one component of the overall CERP-MAP monitoring program.  In the Southern Everglades, marl prairie habitats are present on either side of Shark River Slough. Vegetation structure and composition gradually change along an elevation gradient from short-hydroperiod marl prairies to ridge and slough, which are characteristic environments of central Shark River slough, and experience varied water depth throughout the year. In the past few decades, management-induced changes in amount and flow pattern of water have altered the relative proportion of prairies and slough vegetation in the region. In the coming years, changes in water management associated with hydrologic restoration will affect vegetation composition in the transition zone between these environments, resulting in a shift of boundaries between prairies and slough. It is therefore important to understand how restoration translates into impacts on prairie and slough landscape. To monitor the changes in vegetation along the prairie-slough gradient, MAP has specified to establish a number of transects extending across Shark River Slough and into the edges of the marl prairie on the eastern and western sides of the slough.  Vegetation characterization in plots at regular intervals along transects extending from marl prairie to slough will help to identify the transition zone, where vegetation composition changes either abruptly or gradually. Repeated sampling in those plots will help to detect changes in the location and structure of this ecotone in response to hydrologic alteration associated with restoration.

2006-Present — CERP MAP Components. Monitoring Tree Islands Conditions: 
Tree islands are among the most distinctive features of the Florida Everglades. Because surface elevation at the center of the tree island is typically higher than the surrounding marsh, a vegetation gradient can usually be identified, with tropical and subtropical hardwood species inhabiting the better-drained interior positions and swamp species of mainly temperate origin dominating the frequently flooded edge locations. Tree islands cover less than five percent of the Everglades, yet they perform many vital ecosystem functions, including nutrient cycling and provision of wildlife habitat, and have historical and cultural significance as sites of human habitation (van derValk and Sklar 2002). Maintaining and/or restoring the health of tree islands (and other Everglades habitats) requires ongoing monitoring of tree island conditions as they relate to various management practices. The objective of the ongoing tree island project are as follows: (1) Monitoring Tree Islands especially focusing on hardwood hammocks in Shark Slough, supports a future evaluation of species richness variation in Tree Islands ecosystems. (2) Explore relationships between hydrology, soil moisture and plant stress and population dynamics in Tree Islands. (3) Detect environmental changes that might affect Tree Island plant communities, especially focusing on distinguishing changes related to hydrology versus natural disturbance or stand succession. This project employs  two types of Tree Islands monitoring: (a) Extensive permanent plot islands, which include 16 islands in Shark Slough, sampled twice each year; (b) Intensive permanent plots, which include 3 islands in ENP, sampled six times per year.

 2001-2006 — Shadehouse Study:
 Tree island vegetation is one of the most sensitive components of the Everglades landscape to changes in regional hydrology. Prolonged periods of high water may adversely affect the condition of tree island vegetation via death or dieback in flood intolerant species. Similarly, persistent low water may create conditions of extreme fire risk, during which vegetation may be catastrophically damaged. Management-oriented changes in water-flow pattern in the Everglades have resulted in such hydrologic extremes. Maintaining and/or restoring the health of tree islands (and other Everglades habitats) are components of the Comprehensive Everglades Restoration Plan (CERP), a multi-agency project designed to restore and enhance the freshwater resources and natural environments of southern Florida (USACE 1999). Consequently, there is a need within CERP for tools to assess the health of tree islands and to relate these measures to the hydrologic regime to which they are exposed. In order to gain insight into species responses in the field, a controlled study combining morphological and physiological measurements on a broad range of hydric and mesic tree island species growing under different hydrologic regimes is needed. In our shadehouse experiment, twelve tree species common in Everglades tree islands were subjected to three hydrologic regimes under controlled conditions for 25 weeks and assessed for growth and physiological responses. Treatments representing high, low, and no flood were maintained in pools of water to mimic seasonal variation in water depths at different positions in tree islands. The arrangement of species according to their responses to experimental flooding roughly paralleled their spatial distribution in the tree islands. The gradient in species responses demonstrated in this experiment may help guide responsible water management and tree island restoration in the Everglades. 

1996-2003 — The L-31E Surface Water Rediversion Pilot Project Final Report: 
Implementation, Results, and Recommendations:  Throughout the southern Biscayne Bay watershed, existing coastal wetland communities have been cut off from sheet flow for decades. With the expectation that reconnection of these wetlands to upstream water sources would alter existing hydrologic conditions and recreate a more natural sheet flow to Biscayne National Park, a demonstration project on freshwater rediversion was undertaken. The objectives of the project were to document the effects of freshwater diversion on: (a) swamp and nearshore water chemistry and hydrology; (b) soil development processes; (c) macrophyte and benthic algal community composition, structure, and production; (d) abundance of epiphytic and epibenthic invertebrates; (e) zonation, production, and phenology of primary producers in the nearshore environment, and (f) exchanges of nutrients and particulates between nearshore and mangrove ecosystems.