Explanation of Indicator
Many ecosystems, particularly those in tropical and subtropical regions, are vulnerable to disturbance and invasion by introduced non-indigenous plant species. Such invasions have social, economic, and environmental impacts and focus attention on the threats these plants place on unique and irreplaceable ecosystems. Melaleuca, Brazilian pepper, Australian pine, and Chinese tallow are four of the problem upland exotic plants in Florida.
Melaleuca was introduced into Florida as an ornamental at the beginning of this century. Later, it was purposely introduced into the Everglades in an ill-advised attempt to turn “useless swamps” into valuable land. During the last several decades, melaleuca has rapidly expanded its range into wetland habitats and urban and rural landscapes. Melaleuca infestations have increased fifty-fold at many sites over a period of 25 years. Melaleuca infests pine flatwoods, hardwood bottomlands, cypress forests, freshwater marshes, sawgrass prairies, and mangrove communities as well as improved pasture, natural rangeland, idle farmland, urban areas, and other areas.
The Brazilian pepper tree is an aggressive perennial weed in southern Florida. Introduced as an ornamental in Florida, Brazilian pepper forms dense, ten-meter high thickets in poorly managed pastures, abandoned agricultural land, along roadsides, on canal banks, and in pine woods and hammocks. The tangled branches makes it difficult to clear the land. In Everglades National Park, its rapid invasion threatens the destruction of part of the natural ecosystem. It covers thousands of acres in south and central Florida, the Florida keys, and other islands off the state’s east and west coasts.
Australian pine has invaded large sections of the remaining undeveloped portions of the barrier islands along the Atlantic and Gulf coasts in southern Florida. This exotic poses the greatest threat to native beach plant communities of southern Florida. It is resistant to salt spray and can grow close to the high tide line. The species tends to invade newly exposed sand and calcareous rubble, such as newly accreted beaches, areas where dredge spoil has been dumped, and beaches where storms have destroyed existing vegetation. It has been suggested that the Australian pine may interfere with the nesting of the American crocodile and sea turtles.
The Chinese tallow, native to eastern Asia, is a popular landscaping plant that has become naturalized in numerous places in Florida. Chinese tallow possesses the classic characteristics of most invasive pest species: it grows quickly, fruits when young, produces abundant seeds, resists native insects and diseases, grows in a wide range of soils, invades disturbed habitats, and is promoted and distributed by humans for its attractive ornamental qualities. Furthermore, the high content of allelopathic chemicals in the Chinese tallow are toxic to native fish, aquatic invertebrates, and macrofauna.
Data Characteristics
SOURCE
Information on melaleuca, Brazilian pepper, and Australian pine is in the report An Assessment of Invasive Non-Indigenous Species in Florida’s Public Lands, obtained from Don Schmitz, Wetland and Upland Alien Plant Coordinator, Bureau of Aquatic Plant Management, Florida Department of Environmental Protection (DEP), Collins Building, 2051 East Dirac Drive, Tallahassee, Florida 32310, or at (904) 488-5631. Chinese tallow information can be obtained from Greg Jubinsky, Environmental Administrator, Bureau of Aquatic Plant Management, Florida Department of Environmental Protection, 3917 Commonwealth Boulevard, MS 710, Tallahassee, Florida 32399-3000, or at (904) 487-2600.
ACQUISITION
This data can be obtained in a hard copy format for melaleuca, Brazilian pepper, and Australian pine at no cost. Acreage estimates for Chinese tallow are not available.
COLLECTION
The data are collected on an annual basis, statewide.
Data Limitations
The biggest limitations to this data are that the information is collected statewide, not by county, and that there are currently no data available on Chinese tallow. The data in this indicator should be used as a benchmark until further data are available.
Data Analysis
Melaleuca is among the most problematic of 33 major exotic pest plant species that are destroying the biological diversity of Florida's natural wetland and upland areas. Most threatened among these is Florida's Everglades. Congressionally mandated efforts to establish more natural hydrologic cycles, improve water quality, and preserve unique species will cost millions of dollars over the next decade. Melaleuca, already present on 448,824 acres in southern Florida, threatens these efforts to restore this natural resource. Melaleuca also occurs in southern California and Hawaii and could survive in most coastal areas along the Gulf Coast.
In the south Florida region (from the north rim of Lake Okeechobee south to Florida Bay), melaleuca has infested 448,824 acres, the Brazilian pepper over 600,000 acres, and the Australian pine 373,723 acres. Generally, melaleuca, Brazilian pepper, and the Australian pine are found from mid-Brevard County transecting to mid-Pinellas County and extending to the southern border of Florida. The acreage estimates presented are not a comprehensive assessment because the area north of Lake Okeechobee has not yet been assessed.
In the last decade the Chinese tallow tree has aggressively invaded many wetlands, lake, and river margins, as well as disturbed and undisturbed uplands. Several small trees have been observed in tidal estuarine and coastal wetlands. Originally introduced into South Carolina, it is now naturalized in the southern coastal plain from South Carolina to Florida and west to Texas. According to a 1993 survey by DEP, the tree was found in 38 of the 67 counties in Florida (57 percent). Of those 38 counties, 25 counties have trees that are primarily associated with ornamental landscapes with only occasional outlier trees. Thirteen counties had numerous populations of trees present that are outside of the ornamental landscape and numbered more than fifty trees per cluster. Preliminary observations during the spring and summer of 1994 indicate a substantial increase in numbers of individuals in existing populations and considerable increase in new infestations. An acreage estimate on Chinese tallow is not available at this time.
Species Infested Acres Melaleuca 448,824 Brazilian pepper 602,504* Australian pine 373,723