Janet Phipps, Ph. D./Environmental Resources Management
Pond Apple Habitat three months after completion of construction. The
Palm Beach Community College's environmental organization, Community:
EARTH, members volunteering to install native plants on the pond apple
islands.

by Janet J. Phipps, Ph.D. and Carman N. Vare, Palm Beach County Department of Environmental Resources Management West Palm Beach, Florida

Background

Palm Beach County, located in southeastern Florida, has a natural freshwater lake system, which is relatively rare for Florida. The present day lakes are remnants of a once-natural system of open water and extensive wetlands located along the western slope of the Atlantic Coastal Ridge. This chain-of-lakes system, which extends approximately 30 miles north-south, has been drastically altered by dredging, filling, and channelization. The system is interconnected with a complex web of drainage canals created in the 1900s and 1940s to "drain the swamps" of Florida. In fact, several smaller lakes in the chain have been filled and now are represented by wider spots in the canal network which interconnects the larger lakes and the drainage canals. The lakes discharge to the Lake Worth Lagoon; thus, they are essentially flow-through systems (Vines, 1970). In addition, western Palm Beach County, once dominated by farmlands is rapidly being converted to urban/residential developments. As a result of all these impacts, the lakes are virtually devoid of their filter marshes, and water quality degradation, due to increasing nutrient and pollutant inflow, is on-going.

This chain-of-lakes is very important to Palm Beach County for processing and storing stormwater as well as for recreational uses, including fishing, boating, and shoreline activities, such as picnicking. Fishing pressure on these lakes equals or exceeds that for the average freshwater body statewide, and Florida itself sustains the largest recreational angling effort in the United States (Morello, 1984).

The County recognizing the importance of these lakes and their degradation completed a one-year evaluation study with recommended solutions, the State of the Lakes Plan, which was adopted by the Board of County Commissioners in January, 1998. One goal of the Plan was to recreate wetlands (filter marshes) to replace those lost due to development. These created wetlands, in addition to providing fisheries and wildlife habitat would also filter sediments, uptake nutrients, and provide shoreline stabilization. The proposed restoration projects were also evaluated and prioritized, and the Pond Apple Habitat was rated as a first priority project.

Site Information

Pond Apple Habitat encompasses both sides of a finger canal which connects to Lake Osborne, a 400-acre lake located in central Palm Beach County. The project is located on land owned by the County, part of John Prince Park, and the local community college who with the Florida Fish & Wildlife Conservation Commission, is also a partner in this project. This location is unique in that it supports a 0.3 acre stand of mature pond apple trees (Annona glabra). These trees represent one of the few remaining such resources within the entire County, and enhancing and creating additional wetlands around the pond apples was one of our goals.

Janet Phipps, Ph. D./Environmental Resources Management
Pond Apple Habitat five months after completion of construction. The
plants quickly spread in the littoral shelves and the pond apples show
their spring growth of leaves. 

Project Construction

The first step was to remove the extensive stand of exotic vegetation. Over 300 mature Australian pine (Casuarina sp.), mahoe (Hibiscus tiliaceus), melaleuca (Melaleuca quinquenervia), rubber tree (Ficus sp.), and earleaf acacia (Acacia auriculiformis) trees were removed with heavy equipment. The pond apples originally were heavily overgrown with Brazilian pepper (Schinus terebinthifolius), an exotic, which required special care for removal to protect the native trees. The sizes of the pepper required heavy equipment for its removal, and fortunately the wet soils enabled the driver of the track excavator with a thumb to carefully grab the pepper and pull it out almost vertically, roots and all, with minimal disturbance to the pond apples. Pepper trunks extensively intertwined with the pond apples were cut to ground level and treated with a herbicides. All exotics were chipped on site and chips and tree trunks were disposed offsite, either to a landfill or used as mulch.

The uplands were scraped back to create gradually sloping littoral shelves with widths ranging from 60 to 100 ft. Approximately 2.5 acres of vegetated littoral wetlands, including the transitional banks, were created which essentially doubled the canal width and added shallow-water habitat to an area where it previously did not exist. A deeper open water "trench" was cut landward between the pond apples and the 60 ft. wide littoral shelf. The transitional banks of the littoral shelves were sloped 1V:5H to existing grade.

This project area was historically a wetland, which is true of most of southeast Florida. We discovered that the northwest portion of the project had not been partially demucked and filled in the past. This area of what appeared to be bottomless muck was difficult to scrape down and necessitated a vigilant and well-experienced driver on the excavator to keep it from sinking out of sight while creating the littoral shelf. Also at that location, the excavator hit a pocket of water encased in the mucks which spurted upward and made us think, at first, we had hit a water line. In all, approximately 10,000 cubic yards of spoil/muck were removed to create the shallow-water zones. This spoil was used by our Parks Department for parks improvements.

Planting consisted of creating tree groups interspersed among the herbaceous wetlands. Two large tree groups were created on the opposite bank from the existing pond apples to enlarge the hardwood wetland area. Approximately 240 trees varying in heights from 6 to 12 ft. were installed. We learned that the shorter trees established quicker since they were not as prone to leaning and were less susceptible to winds while establishing a good root system. The littoral areas were planted with over 16,000 herbaceous plants. All plants and trees were supplied by local nurseries to ensure using plants with genetic makeup consistent with the area. Herbaceous plants were bare root specimens either nursery-grown or field collected under permit from approved sites. The planting plan was designed to accommodate open water views for the public, and for that reason also, flowering species were used extensively. The herbaceous plants were planted in species groups on 18-24 in. centers.

Osmocote fertilizer was used for all plants/trees installed above water. Osmocote was placed in each hole before the plant was added. No fertilizers were used for the in-water plants. The planting contractor (Coastal Revegetation, Inc.) had found that if fertilizers are used in our nutrient-rich waters, algae blooms occur which jeopardizes the newly-installed plants and also makes exotic plant control more difficult.

Lessons Learned During Construction:

In an area such as a park, one of the problems frequently encountered in wetland restoration is how to keep the lawn maintenance people from mowing down the project plants. At a previously-constructed project of similar scope, dune sunflowers (Helianthus debilis) recruited on the bank tops of the transitional zones. We found that copying nature gave the project a line of flowering plants which clearly marked "end of project" for the maintenance crew; thus solving a long term maintenance concern. In addition, dune sunflowers are adapted to a dry environment and worked well at this location.

During construction of this project, the earthwork contractor was challenged by several torrential rains and Hurricane Irene. This clearly showed us the stormwater runoff pattern from the adjacent road. As a result two stormwater flumes were added. The flumes were designed as "beds" approximately 20 x 12 ft. with filter fabric under 6 in. of bedding stones (1-4 in. diameter) covered with limerock boulders ranging in sizes from 12-18 in. diameter. The design funneled the stormwater over the rocks to slow the flow rate to prevent washouts and to trap solids in the rocks before entering the lake.

The initial project plan left shallow open water areas to experiment with relocating eelgrass (Vallsineria americana) into the project. We discovered that the eutrophic condition of the lake water coupled with the muck soils in the northern portion of the project caused the herbaceous plants, specifically pickerelweed, bulrush and spikerush, to quickly fill in these open areas, leaving no place for the eelgrass.

Janet Phipps, Ph. D./Environmental Resources Management

Wildlife Use:

More trees were added to expand the existing hardwood wetlands in the hopes that a heronry would develop. Two pairs of tricolor herons (Egretta tricolor) had previously nested in the pond apples, and following completion of construction, a limpkin (Aramus guarauna) pair fledged young from the pond apples, too. The endangered wood stork (Mycteria americana) and other herons, egrets and ibis began foraging in the shallows while heavy equipment was still on site and before installation of plant material. A platform was installed on an inactive utility pole that was left on site in the hopes of attracting osprey (Pandion haliaetus). So far, ospreys are using the platform for resting and feeding.

During and after construction several American alligators (Alligator mississippiensis) have been observed regularly at the project. A pair of river otters (Lutra canadensis) have adopted the area and are observed regularly, and a pair of large green iguanas (Iguana iguana), exotic releases from the pet trade, have also adopted the area. The college's environmental science group also releases rehabilitated wildlife at the project. To date, turtles and several bird species have been successfully released, and a recently-released red-shouldered hawk (Buteo lineatus) continues to hang around the project.

Maintenance and Monitoring

For the first year after construction, maintenance and monitoring were conducted monthly. With all the exotic plants around and our warm climate, a constant vigil is essential while the native plants are getting established. Melaleuca is the most aggressive species, and by having a frequent schedule of monitoring early on, eradication is easier and cheaper by handpulling seedlings. Torpedo grass (Panicum repens), is also aggressive and must be treated with herbicides. In addition, control of primrose willow (Ludwigia sp.) and cattails (Typha sp.), both natives, is necessary as these species, like the exotics, will form monocultures in open disturbed areas.

Funding

The total costs of the project was $123,000. Funding was provided by the Florida Fish & Wildlife Conservation Commission's Lake Restoration Fund, County vessel registration fees, the Palm Beach Community College, and in-kind services by the County for project plan/design development, permit acquisition, contract development, project management, and long-term maintenance. Project construction was initiated August, 1999 and completed 3 months later.

Conclusions

The project has been an overwhelming success. One of the most important aspects for a project like this is to have it adopted by the community. In this project we had full and enthusiastic support from our partners, the Florida Fish & Wildlife Conservation Commission and the Palm Beach Community College, and our sister department, Parks & Recreation. The college not only provided funding toward the exotic removal, but the faculty and students have become the project's long-term caretakers. Since environmental science classes are taught at the college, this project also provides an outdoor classroom.

The project has become a jewel to enjoy by the students, visitors, and residents of the County. Local fishermen now regularly use this finger canal. The Florida Native Plant Society awarded the project first place in their statewide competition for ecosystem restoration in 2000. In addition, the Treasure Coast Chapter of the Florida Association of Environmental Professionals also awarded the project first place for habitat restoration in 2000.

This presentation was given at the North American Lake Management Society Conference 2000, held in Miami, Florida.