Everglades Cooperative Invasive Species Management Area

ECISMA NEWSLETTER VOLUME 6 JULY 2015 Managing at the wrong end of the Invasion Curve: Shoebutton ardisia in the Miami-Dade County South Dade Wetlands Preserve By Gwen Burzycki and Cynthia Guerra, Miami-Dade County Environmentally Endangered Lands (EEL) Program (Graphic courtesy of SFWMD and ECISMA) Shoebutton ardisia (Ardisia Counties. In the 1980s, Ardisia elliptica) is an evergreen shrub elliptica was found to be invasive or small tree native to Asia. It is within Everglades National Park. a summer-flowering, fall-fruiting Since then, the extent and range species that is closely related of Ardisia elliptica has expanded to the native marlberry (Ardisia as it displaces both native and escallonioides), an uncommon invasive exotic plant species. shrub found in South Florida Because it impacts community hammocks. The native marlberry is structure and ecological function not abundant due to the presence of native habitats, Ardisia elliptica of a native seed predator which is a Category 1 invasive on the renders up to 90 percent of its Florida Exotic Pest Plan Council seed non-viable. There is no known Invasive Plant List. Category 1 seed predator in South Florida for plants are defined as “Invasive Ardisia elliptica and birds and other exotics that are altering native wildlife disperse the seeds. plant communities by displacing native species, changing Originally imported as an community structures or ecological ornamental plant in the early functions, or hybridizing with 1900s, Ardisia elliptica has become natives.” The desired outcome in a prolific invasive species that is managing this invasive species very expensive to control. Ardisia is to find and implement a cost- elliptica is now commonly found effective control. in short hydroperiod wetlands, hammocks and tree islands in First spotted outside Everglades Miami-Dade, Broward, Palm National Park during vegetation Beach, St. Lucie and Brevard mapping in 1990, Ardisia elliptica to Triclopyr amine but Imazapyr is not appropriate for all habitats and can result in high non-target damage to surrounding plants like buttonwood (Conocarpus erectus) and white mangrove (Laguncularia racemosa). Detection of Ardisia elliptica by aerial survey is not effective. Finding infestations can be difficult in remote areas and requires ground verification. On average, initial control of Ardisia elliptica has cost up to $11,000 per acre for selective hand treatment by a crew of six individuals, walking an area looking for and treating seedlings, saplings and trees. After initial treatment opens up the canopy, the Ardisia elliptica seed bank responds to increased light levels, and second Mechanical clearing in the south Dade wetlands. (Photo courtesy Miami-Dade County year treatments can cost up to Environmentally Endangered Lands Program) $9,000 per acre to address all of expanded to several hundred South Dade Wetlands Preserve, the new seedlings. By the third acres by 1996. Today, there and that work continues today. year, most of the seed bank is are approximately 4,000 acres The control effort is limited exhausted and the cost decreases of Ardisia elliptica within and because not all of the land within to less than $6,000 per acre, with adjacent to the Miami-Dade the Preserve has been acquired. subsequent annual maintenance County South Dade Wetlands Invasive species present on treatments averaging between Preserve, an important wetland private lands, including Ardisia $1,000 and $1,500 per acre. In system in the southern part of elliptica, are not being treated, native-dominated wetlands, the County. Land in this area so the private parcels act as a treatments must occur every is targeted for acquisition and seed source. Control of Ardisia three to four years because the management by the County’s elliptica is further complicated Ardisia elliptica is co-located Environmentally Endangered because field identification is with listed and rare species that Lands (EEL) Program because of difficult as the invasive strongly will be displaced if the habitat is its strategic location between two resembles the native marlberry not maintained free of invasive national parks, Everglades National and dahoon holly (Ilex cassine). species. The EEL Program has Park and Biscayne National Field crews must undergo training treated more than 350 acres Park, and within the watersheds and gain practical experience through selective hand treatment of Florida Bay, Biscayne Bay, so they properly identify the and follow-up maintenance Card Sound and Barnes Sound. correct species to treat. In activities. Ardisia elliptica extends up the controlled studies, the chemical coast within Miami-Dade County, Triclopyr amine was over 90 especially in coastal wetlands that percent effective at reducing are already impacted by Brazilian cover of Ardisia elliptica with one pepper or in areas that have been application. The effectiveness rate farmed in the past. Ardisia elliptica of Triclopyr amine is diminished spreads rapidly in nutrient enriched in the field when plants in dense soils such as those that have been stands are inadvertently missed altered by farming, and tolerates during treatment. Re-sprouting longer hydroperiods than Brazilian plants and massive seed pepper. germination with increased light after initial treatment requires Beginning in 2002, the EEL Program Ardisia elliptica is a fall-fruiting species. (Photo repeated follow-up treatments. by Anne Murray, courtesy University of implemented a concerted effort The chemical Imazapyr has been Florida/IFAS Center for Aquatic and Invasive to treat Ardisia elliptica within the used as an alternative supplement Plants) ECISMA NEWSLETTER VOLUME 6 JULY 2015 With selective hand treatment by biological control in development between whether to maintain crews, the control costs for Ardisia due to the presence of a closely what has already been restored elliptica were too high to be related native species in the same or respond to new or expanding sustainable over the entire 4,000 genus. In total, the EEL Program threats. ♦ acres. To reduce costs in areas has spent almost $5 million to that are dominated by invasive control Ardisia elliptica and other To learn more about Shoebutton vegetation, treatment efforts are associated invasive species in ardisia (Ardisia elliptica), visit the now being used to manipulate the the South Dade Wetlands since University of Florida IFAS website: habitat to make it less suitable for 2000. More research on the http://plants.ifas.ufl.edu/node/43 Ardisia elliptica. In dense stands demographics and life cycle of of Ardisia elliptica, the current Ardisia elliptica is needed. Specific strategy is to use heavy machinery information on the relationship such as a gyrotrack or brontosaurus to soil nutrient characteristics, mulcher to grind up both native response to prescribed fire, seed and exotic woody material, with banks and dispersal vectors can follow-up mowing and aerial all inform management decisions spraying. The land is allowed to and help to reduce management convert to prairie, which then costs. Most importantly, consistent can be maintained through the and sustained funding is needed application of prescribed fire. By to help bring this species under early 2014, the EEL Program had permanent control. Funding comes successfully converted 26 acres to in cycles, but the invasion doesn’t prairie, and had another 22 acres slow down or stop without active in process. This treatment method management. Lacking sustained has averaged about $3,000 per and sufficient funding, land acre for mulching, and not more managers are forced to prioritize Shoebutton ardisia (Ardisia elliptica) is a than $300 per acre for mowing their management strategies, summer-flowering species. (Photo by Anne or aerial spraying. In treated which often means choosing Murray, courtesy University of Florida/IFAS Center for Aquatic and Invasive Plants) areas, there has been significant recruitment of native grasses. While not yet applied, prescribed fire is expected to cost less than $100 per acre. As a side note, it is important to use proper phytosanitation and equipment decontamination practices when using heavy equipment. Some exotic grasses can be brought in unintentionally, especially on mowers. Additionally, mulching is preferable to land clearing and grubbing because soil disturbance may also result in new infestations of undesirable species like cattail (Typha species). A primary management goal of the EEL Program is to reduce the amount of exotics-dominated forested wetlands to provide for a diverse ecological community, including habitat for listed ferns, bromeliads and orchids. A critical component of this management goal is to reduce coverage of Ardisia elliptica to make control cost-effective and feasible in the long-term. This is especially The ripened fruit of Ardisia elliptica. (Photo by Anne Murray, courtesy University of Florida/IFAS important because there is no Center for Aquatic and Invasive Plants).

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