United States Department of Weed Risk Assessment Agriculture for quinquenervia Animal and Health () – Melaleuca Inspection Service

May 9, 2020

Version 1

Left: Melaleuca are showing light-colored, spongy bark (David Nance, USDA Agricultural Research Service, Bugwood.org). Top right: Population on a ridge off of the Hana Highway in Maui (20.8675272,-156.176852; Google, 2020); Bottom right: and fruit capsules (Forest and Kim Starr, Starr Environmental, Bugwood.org); Additional images are shown in Appendix B.

AGENCY CONTACT Plant Epidemiology and Risk Analysis Laboratory Science and Technology

Plant Protection and Quarantine (PPQ) Animal and Plant Health Inspection Service (APHIS) United States Department of Agriculture (USDA) 1730 Varsity Drive, Suite 300 Raleigh, NC 2760 Weed Risk Assessment for (Melaleuca)

Executive Summary

The result of the weed risk assessment for Melaleuca quinquenervia is High Risk. Melaleuca quinquenervia is a tropical woody that grows in coastal swamps and wetlands. It was introduced to the United States in 1886 by a nursery for cultivation, and by the early 1900s, it was being promoted and used for multiple purposes in the state. It first started to escape and spread in the 1920s, but it was not until the 1970s that experts recognized it as a significant threat to natural areas in Florida. Melaleuca has a high reproductive capacity and produces millions of small seeds. It retains the seeds in woody capsules in the canopy until a disturbance, such as fire, stimulates the release of the seeds. The seeds then germinate and grow to produce dense populations that exclude native plant . Melaleuca is particularly well adapted to the Florida , where periodic natural fires are an important process in plant communities. In that ecosystem, it transforms many plant communities into monospecific dense forests. Furthermore, because it changes the natural fire regime by increasing fire intensity, it is able to promote its own invasion. Melaleuca also poses a fire-safety risk to people and dwellings, and in agricultural areas, it reduces the productivity of rangelands and pastures. Considerable amounts of resources have been spent on control in Florida. Several biological control agents that have been released in the state are helping to reduce population growth and reproduction. Florida and other states regulate M. quinquenervia as either, a state noxious weed or a prohibited aquatic plant.

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Plant Information and Background

PLANT SPECIES: Melaleuca quinquenervia (Cav.) S. T. Blake (Myrtaceae) (NGRP, 2020)

SYNONYMS: Basionym: quinquenervia Cav. (NGRP, 2020)

COMMON NAMES: Melaleuca, broadleaf paperbark (NGRP, 2020), punk tree (Dray et al., 2006), cajeput, bottle-brush-tree, paper-bark tree (Godfrey and Wooten, 1981)

ADDITIONAL NOTE: Melaleuca quinquenervia is a member of the M. leucadendra species complex which includes 14 species, all of which are broad-leaved paperbarks that occupy sites subject to flooding (Cook et al., 2008). Melaleuca leucadendron (L.) L. has been misapplied to this species (Blake, 1968; Godfrey and Wooten, 1981). During the early 1900s, M. quinquenervia was introduced into the United States and sold under the names of Melaleuca leucadendron (L.) L., M. viridiflora (L.f.) Byrnes, and Cajeput leucadendra (Stickm). Rusby, which are similar to M. quinquenervia (Dray et al., 2006). Melaleuca quinquenervia can be distinguished from other members in this group based on and floral traits (cited in Serbesoff-King, 2003).

BOTANICAL DESCRIPTION: Melaleuca quinquenervia is a large, evergreen subtropical tree, growing up to 33 m tall with ascending branches on young trees and drooping and irregular on older trees (Godfrey and Wooten, 1981; Serbesoff-King, 2003). The bark is thick and very spongy, whitish at first, and exfoliating in buff to pale cinnamon-colored papery layers in mature trees (Godfrey and Wooten, 1981). The are aromatic, narrowly elliptic to lanceolate-elliptic in shape, 4 to 12 cm long, and with the principal veins parallel (Blake, 1968; Godfrey and Wooten, 1981; Serbesoff-King, 2003). The whitish flowers are arranged in terminal spikes or panicles of spikes on woody axes (Blake, 1968). The fruit are short cylindrical to squarish woody capsules, 3 to 5 mm long, arranged along the stem and may persist for a while (Godfrey and Wooten, 1981). The capsules dehisce to release many reddish brown seeds that are 0.5 to 1 mm long (Godfrey and Wooten, 1981; Serbesoff-King, 2003). The apices of flowering twigs resume growth after flowering, leading to the appearance of woody fruits being sandwiched between groups of leaves (Godfrey and Wooten, 1981).

INITIATION: This assessment was done as part of a review of the U.S. status of this federal noxious weed.

WRA AREA1: United States and Territories

FOREIGN DISTRIBUTION: Melaleuca quinquenervia is native to , Papua , and (NGRP, 2020). It has become naturalized in India, the , Guyana, (NGRP, 2020), and South (Jacobs et al., 2015). In the Bahamas, it is currently naturalized but

1 The “WRA area” is the area in relation to which the weed risk assessment is conducted (definition modified from that for “PRA area”) (IPPC, 2017).

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appears to be spreading as there are numerous juvenile trees on the periphery of populations (Pratt et al., 2007). It was introduced to Madagascar for reforestation and cultivation for its essential oils, but has since escaped and become invasive in eastern lagoons and wetlands (Kull et al., 2019; Miandrimanana et al., 2014). It is considered to be invasive in the Dominican Republic and Bahamas (Kairo et al., 2003), and is becoming invasive at a seasonally inundated savanna in French Guiana (Delnatte and Meyer, 2012). Melaleuca quinquenervia has been introduced for cultivation to several other countries including Benin, Costa Rica, Egypt, Mexico, Senegal, Taiwan, Uganda, and the Dominican Republic (Dray et al., 2006; Pratt et al., 2005; Sánchez-Silva, 2004). It has been widely introduced to the Caribbean (Kairo et al., 2003).

U.S. DISTRIBUTION AND STATUS: Melaleuca quinquenervia is naturalized in Florida, , Puerto Rico, and Guam (Kartesz, 2020; NRCS, 2020; Sherley, 2000). It has been reported from the U.S. Virgin Islands (Pratt et al., 2005) and specimens from cultivated have been collected from (Baldwin, 2020; Ritter, 2020; SEINet, 2020), Louisiana (Doffitt, 2020; Hardy, 2020; Kartesz, 2020), and Texas (Dray et al., 2006; Singhurst, 2020). It is primarily distributed in peninsular Florida where it has been reported from 29 counties (Anderson, 2020; EDDMapS, 2020; Wunderlin and Hansen, 2020) and documented to infest at least 499,000 acres of wetlands in South Florida (Bodle et al., 1994 in Turner et al., 1997). Melaleuca is regulated as a U.S. federal noxious weed (7 CFR § 360, 2019), and as a state noxious weed or invasive aquatic plant in Florida (FDACS, 2016), Louisiana (LAC 76 § VII-1101, 2020), Mississippi (NPB, 2020), Puerto Rico (DRNA, 2008), South Carolina (NPB, 2020), and Texas (NPB, 2020; TAC, 2013). In Florida, considerable effort has been invested in mapping and controlling this species over the years (Laroche, 1999; Laroche and McKim, 2004). Three biological control agents that were released between 1997 and 2008 have become established in Florida, and have since suppressed melaleuca populations (Center et al., 2012; USDA-ARS, 2018). Resource managers emphasize the use of integrated weed management strategies that combines biological control with mechanical and chemical control (Laroche, 1999; Tipping et al., 2018). Recently, three government agencies, including USDA-ARS, entered into a new long-term collaborative effort to continue developing and promoting the use of biological control agents (Lake et al., 2017). The South Florida Water Management District has budgeted for fiscal year 2019-2020 almost $5,000,000 (including matching funds from the Fish and Wildlife Commission) for ongoing control efforts (SFWMD, 2019).

Analysis

ESTABLISHMENT/SPREAD POTENTIAL: Melaleuca quinquenervia’s ability to establish and spread has been well documented in Florida (Serbesoff-King, 2003) and elsewhere (Delnatte and Meyer, 2012; Kull et al., 2019; Miandrimanana et al., 2014; Pratt et al., 2007). It is self-compatible (Rayamajhi et al., 2002), begins flowering within a few years of germination (Dray et al., 2006), may several times per year (Serbesoff-King, 2003), and produces millions of seed (Rayachhetry et al., 1998; Rayamajhi et al., 2002). The seeds are small and dispersed by wind (Woodall, 1982) and

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water (Wade et al., 1980). Plants form dense, shallow or deep root systems that tolerate fluctuating water regimes and competing vegetation (Silvers et al., 2007). They also have several traits that make them well adapted to periodic fire (Turner et al., 1997). In particular, they retain most of their seeds in woody capsules in the canopy. When fire, stem damage, girdling, or any other disturbance occurs that interrupts vascular flow, plants release their seeds. When stressed, a single tree may release as many as 20 million seeds at a time, which presents a big challenge for management (Serbesoff-King, 2003). Thus, its biology makes it well-suited to invade fire-prone wetlands. Because its biology is well-understood, we had low uncertainty for this risk element.

Risk score = 18.0 Uncertainty index = 0.08

IMPACT POTENTIAL: Melaleuca quinquenervia causes a wide range of impacts in natural, anthropogenic, and agricultural systems. In Florida natural communities, it readily transforms open herbaceous wetlands into closed-canopy forests within 25 years (Laroche and Ferriter, 1992), excluding most of the native plant community (Schmitz and Hofstetter, 1999) and affecting animal communities as well (O'Hare and Dalrymple, 1997). Expansion into seasonal wetlands in the water conservation districts in southern Florida eliminates critical habitat for the U.S. Threatened stork (Mycteria americana) (Bancroft et al., 1992). It also alters ecosystem processes such as fire regime (Schmitz and Hofstetter, 1999) and soil accretion (Center et al., 2012; Mazzotti et al., 1988). Hotter fires in pine and cypress stands cause canopy fires that can kill native trees but minimally damage melaleuca, which then further promotes the invasion (Center et al., 2012; Tipping et al., 2009; Weston, ND). In anthropogenic systems, the fires promoted by melaleuca also pose a safety risk to people (Schmitz and Hofstetter, 1999; Weston, ND). An economic study commissioned by the Florida Department of Environmental Protection concluded that unchecked spread of the species would severely restrict use of south Florida’s parks and recreation areas by local residents and tourists, resulting in a potential loss of about $168.6 million annually (Diamond et al., 1991 in Mazzotti et al., 1988). Because M. quinquenervia also invades agricultural areas such as rangelands and pastures, it reduces agricultural productivity and forces landowners to control it through various means (Blanfort and Orapa, 2008; Finn, 2006). In a survey of Florida agricultural managers, seven percent of the respondents reported spending $244,000 on special equipment to control melaleuca (Finn, 2006). Melaleuca has also been reported to be a respiratory irritant, causing sinus and nasal congestion, coughs, sneezing, headaches, and nausea (Morton, 1966); however, one clinical study found no evidence to support this claim (Stablein et al., 2002).

Risk score = 4.3 Uncertainty index = 0.05

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RISK MODEL RESULTS: The risk scores for establishment/spread and impact potential were used to estimate the probabilities of invasiveness and overall risk result.

Model Probabilities: P(Major Invader) = 93.7% P(Minor Invader) = 6.1% P(Non-Invader) = 0.2% Risk Result = High Risk Risk Result after Secondary Screening = Not Applicable

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Figure 2. Risk and uncertainty results for Melaleuca quinquenervia. The risk score for this species (solid black symbol) is plotted relative to the risk scores of the species used to develop and validate the PPQ WRA model (Koop et al., 2012). The results from the uncertainty analysis are plotted around the risk score for M. quinquenervia and show other possible risk scores should some of our WRA answers change. The smallest, black box contains the inner 50 percent of the simulated risk scores, the second 95 percent, and the largest 99 percent. The black vertical and horizontal lines in the middle of the boxes represent the medians of the simulated risk scores (N=5000). For additional information on the uncertainty analysis used, see Caton et al. (2018).

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GEOGRAPHIC POTENTIAL: Using the PPQ climate-matching model for weeds (Magarey et al., 2017), we estimate that about 6.3 percent of the United States is suitable for the establishment of M. quinquenervia. This area (Fig. 1) represents the joint distribution of Plant Hardiness Zones 9-13, areas with 20-100+ inches of annual precipitation, and the following Köppen-Geiger climate classes: Tropical rainforest, tropical savanna, Mediterranean, humid subtropical, and marine west coast (App. A). If we only considered those climates for which we have the greatest certainty of suitability, then the percentage of the United States that is suitable decreases to 0.9 percent (Fig. 1). The three climatic variables, specifically, cold plant hardiness zones, annual precipitation, and Köppen-Geiger climate classes were used to determine areas of suitability in the United States. Other factors, such as soil, hydrology, disturbance regime, and species interactions may alter the areas in which this species is likely to establish. In Florida and Australia, M. quinquenervia generally occurs in wet areas such as wetlands, freshwater marshes, brackish swamps, and water corridors (Dray et al., 2006; Mazzotti et al., 1988; Pratt et al., 2007; Silvers et al., 2007).

While estimating its geographic potential, we came across several records of melaleuca from southern California (GBIF, 2020; SEINet, 2020), which receives about 0-20 inches of annual precipitation. However, because most of these records are from cultivated plants, we disregarded them as these plants may be growing in areas that are watered or were watered initially to help them establish. Based on our analysis, we do not believe that southern California is generally suitable for melaleuca to naturalize in, except perhaps in very moist microhabitats. For example, in a small region of , which is climatically similar to southern California, a small naturalized population of about 300 individuals was recently detected in a mountain seep (Jacobs et al., 2015). A separate climate suitability analysis, using the program CLIMEX, did not find any areas in California as climatically suitable (Watt et al., 2009).

We determined that M. quinquenervia can grow in plant hardiness zone 9 (see Appendix A), but perhaps only in its warmest regions. This is based on the species’ minimum temperature range (CABI, 2020; SelecTree, 2020; Serbesoff-King, 2003) and comments and observations about the impact of freezing temperatures on plants (Baldwin, 2020; Landry, 2020; Serbesoff-King, 2003; Turner et al., 1997). Melaleuca is tolerant of infrequent frost and can recuperate from a significant freeze down to -5 °C and below 0 °C for a few hours (Serbesoff-King, 2003). Its southernmost distribution in Australia is around , which is climatically similar to New Orleans (Serbesoff- King, 2003). Because our data layer for plant hardiness zones does not categorize the data at a finer scale, our map (Fig. 2) overestimates the areas in zone 9 that are climatically suitable. Thus, Georgia, South Carolina, central Louisiana, parts of Texas, and the coastal regions of the western United States are most likely not suitable for establishment.

Melaleuca is naturalized on five of Hawaii’s main islands: Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi; (Wagner et al., 1999). Images from the island of Maui show large populations along the Hana Coast (Starr and Starr, 2020a); however, our analysis indicated that only the islands of Hawaiʻi, Kauaʻi, and Oʻahu are suitable for establishment. Our analysis does not accurately reflect the regions that are climatically suitable in Hawaii because our global data layer for average annual precipitation is

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relatively coarse (10 k resolution). That layer shows all of Maui and Molokaʻi as receiving 20 inches or less of annual precipitation (Magarey et al., 2017) when, in fact, high-elevation areas on these islands receive much more rainfall (Giambelluca et al., 2013). For example, the windward side of the volcano Haleakala, above Hana, receives about 400 inches of annual precipitation, while the leeward side around Kihei, which is about 15 minutes further by car, receives only about 10 inches of rainfall (Anoymous, 2020b).

ENTRY POTENTIAL: Because M. quinquenervia is already naturalized in the United States, we did not evaluate its entry potential.

Discussion

The result of the weed risk assessment for Melaleuca quinquenervia is High Risk. Relative to the other 204 species that were used to develop and validate this WRA model, melaleuca obtained a very high risk score. Two independent weed risk assessments of this species using the Australian WRA model resulted in high risk scores as well (Jacobs et al., 2015; UH, 2020). Since the majority of information used in this WRA was obtained from U.S. sources, the species’ risk score can also serve as an indicator of its invasive status in the United States. We are confident (low uncertainty) in our results because the species is relatively well-studied.

Suggested Citation

PPQ. 2020. Weed risk assessment for Melaleuca quinquenervia (Cav.) S. T. Blake (Myrtaceae) – Melaleuca. United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (PPQ), Raleigh, NC. 31 pp.

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Figure 1. Current and potential distribution of Melaleuca quinquenervia in the United States. Climatic suitability was determined using the APHIS-PPQ climate matching tool for invasive plants (Magarey et al., 2017). The known distribution of M. quinquenervia was based on county distribution records from online databases (EDDMapS, 2020; Wunderlin and Hansen, 2020) and other sources (Anderson, 2020). Map components are shown at different scales. Variation in climatic suitability is based on the uncertainty ratings assigned to climate levels (App. A). Thus, very high climate suitability corresponds to areas where the uncertainty rating for all three climate variables was negligible. In contrast, low climatic suitability corresponds to areas where the uncertainty for one or more of the climate variables was high. See text under U.S. Distribution and Status for a discussion about the distribution of cultivated plants.

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Lake, E. C., P. W. Tipping, M. B. Rayamajhi, P. D. Pratt, F. A. Dray Jr., G. S. Wheeler, M. F. Purcell, and T. D. Center. 2017. The role of melaleuca control in Everglades restoration: Accomplishments and future plans. Pages 53-58 in R. G. Van Driesche and R. C. Reardon (eds.). Suppressing Over-Abundant Invasive Plants and Insects in Natural Areas by Use of Their Specialized Natural Enemies (FHTET-2017-02). United States Department of Agriculture, Forest Service, Forest Health Technology Enterprise Team, Morgantown, West Virginia. Landry, G. 2020. Status of Melaleuca quinquenervia in Louisiana. Personal communication to A. Koop on May 6, 2020, from Garrie Landry, Botanist, University of Louisiana at Lafayette. Laroche, F. B. (ed.). 1999. Melaleuca Management Plan: Ten Years of Successful Melaleuca Management in Florida: 1988 - 1998. Florida Exotic Pest Plant Council, Forida. 106 pp. Laroche, F. B., and A. P. Ferriter. 1992. The rate of expansion of melaleuca in South Florida. Journal of Aquatic Plant Management 30:62-65. Laroche, F. B., and J. McKim. 2004. Cost comparison of melaleuca treatment methods. Wildland Weeds Spring:12-15. Mabberley, D. J. 2008. Mabberley's Plant-Book: A Portable Dictionary of Plants, Their Classification and Uses (3rd edition). Cambridge University Press, New York. 1021 pp. Magarey, R., L. Newton, S. C. Hong, Y. Takeuchi, D. Christie, C. S. Jarnevich, L. Kohl, M. Damus, S. I. Higgins, L. Millar, K. Castro, A. West, J. Hastings, G. Cook, J. Kartesz, and A. L. Koop. 2017. Comparison of four modeling tools for the prediction of potential distribution for non-indigenous weeds in the United States. Biological Invasions 20(3):679–694. Martin, P. G., and J. M. Dowd. 1990. A protein sequence study of the dicotyledons and its relevance to the evolution of the legumes and nitrogen fixation. Australian Systematic Botany 3:91-100. Mazzotti, F. J., T. D. Center, A. Dray, and D. Thayer. 1988. Ecological consequences of invasion by Melaleuca quinquenervia in South Florida wetlands: Paradise damaged, not lost. University of Florida, Department of Wildlife Ecology and Conservation, Gainseville, Florida. Last accessed April 10, 2020, https://edis.ifas.ufl.edu/pdffiles/UW/UW12300.pdf. Meskimen, G. F. 1962. A silvical study of the melaleuca tree in South Florida. Master's of Science Thesis (Forestry), University of Florida, Gainesville, FL. Miandrimanana, C., N. Solovavy, R. Marinjakasandrata, and C. B. Birkinshaw. 2014. Approche expérimentale de l’utilisation de glyphosate dans le contrôle de Melaleuca quinquenervia (Myrtaceae), une espèce envahissante dans la réserve communautaire de la forêt d’Analalava- Foulpointe (Madagascar). Madagascar Conservation & Development 9(1):49-53. Morton, J. F. 1966. The Cajeput tree—A boon and an affliction. Economic Botany 20(1):31-39. Neal, M. C. 1965. In Gardens of Hawaii. Bishop Museum, Honolulu, Hawaii. 924 pp. NGRP. 2020. Germplasm Resources Information Network (GRIN). United States Department of Agriculture, Agricultural Research Service, National Genetic Resources Program (NGRP). https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx?language=en. Nickrent, D. 2016. Parasitic plant classification. Southern Illinois University Carbondale, Carbondale, IL. Last accessed 09/28/2018, http://www.parasiticplants.siu.edu/ListParasites.html. NPB. 2020. Laws and regulations. The National Plant Board (NPB). Last accessed January 21, 2019, http://nationalplantboard.org/laws-and-regulations/. NPS. 2020. Off-road vehicle use. National Park Service (NPS), Big Cypress National Preserve, Florida. Last accessed April 17, 2020, https://www.nps.gov/bicy/planyourvisit/orv-use.htm. NRCS. 2020. The PLANTS Database. United States Department of Agriculture, Natural Resources Conservation Service (NRCS), The National Plant Data Center. https://plants.usda.gov/java/nameSearch.

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O'Hare, N. K., and G. H. Dalrymple. 1997. Wildlife in southern Everglades wetlands invaded by Melaleuca (Melaleuca quinquinervia). Bulletin of the Florida Museum of Natural History 41(1):1- 68. Page, S., and M. Olds (eds.). 2001. The Plant Book: The World of Plants in a Single Volume. Mynah, Hong Kong. 1020 pp. Pratt, P., V. Quevedo, L. Bernier, J. Sustache, and T. Center. 2005. Invasions of Puerto Rican wetlands by the Australian tree Melaleuca quinquenervia. Caribbean Journal of Science 41:42-54. Pratt, P. D., M. B. Rayamajhi, C. S. Silvers, and A. P. Ferriter. 2007. Naturalization and biomass allocation of the invasive tree Melaleuca quinquenervia in wetlands of the Bahamas. Journal of Aquatic Plant Management 45(JAN):8-16. Randall, R. P. 2017. A Global Compendium of Weeds, 3rd edition. Department of Agriculture and Food, , Perth, Australia. 3654 pp. Rayachhetry, M. B., T. K. Van, and T. D. Center. 1998. Regeneration potential of the canopy-held seeds of Melaleuca quinquenervia in south Florida. International Journal of Plant Sciences 159(4):648- 654. Rayamajhi, M. B., P. D. Pratt, P. W. Tipping, T. D. Center, J. G. Leidi, and L. R. Rodgers. 2019. Natural- enemies affect the seed and litter fall dynamics of Melaleuca quinquenervia in the wetlands, and influence long-term species diversity in leaf-litter. Wetlands Ecology and Management 27(1):125-139. Rayamajhi, M. B., T. K. Van, T. D. Center, J. A. Goolsby, P. D. Pratt, and A. Racelis. 2002. Biological attributes of the canopy-held melaleuca seeds in Australia and Florida, U.S. Journal of Aquatic Plant Management 40(2):87-91. Ricketts, T. H., E. Dinerstein, D. M. Olson, C. J. Loucks, W. Elchbaum, D. DellaSala, K. Kavanagh, P. Hedao, P. T. Hurley, K. M. Carney, R. Abell, and S. Walters. 1999. Terrestrial Ecoregions of North America: A Conservation Assessment. Island Press, Washington, D.C. 485 pp. Ritter, M. 2020. Status of Melaleuca quinquenervia in California. Personal communication to A. Koop on Mary 4, 2020, from Matt Ritter, Professor, Biological Sciences Department, California Polytechnic State University. Sánchez-Silva, R. 2004. Presencia de Melaleuca quinquenervia (Cav.) Blake (Myrtaceae). Un problema en México. Número Especial 1:67-75. Santi, C., D. Bogusz, and C. Franche. 2013. Biological nitrogen fixation in non-legume plants. Annals of Botany 111(5):743-767. Schmitz, D. C., and R. H. Hofstetter. 1999. Environmental, economic and human impacts. in F. B. Laroche (ed.). Melaleuca Management Plan: Ten Years of Successful Melaleuca Management in Florida: 1988 - 1998. Florida Exotic Pest Plant Council, Forida. SEINet. 2020. Herbarium Data Portal Network. SEINet. http://swbiodiversity.org/seinet/index.php. Serbesoff-King, K. 2003. Melaleuca in Florida: A literature review on the , distribution, biology, ecology, economic importance and control measures. Journal of Aquatic Plant Management 41(2):98-112. SERNEC Data Portal. 2020. Collections Database. SouthEast Regional Network of Expertise and Collections (SERNEC). http://sernecportal.org/portal/index.php#. SFWMD. 2019. Fiscal year 2019-2020 adopted budget division line item report. South Florida Water Management District (SFWMD), West Palm Beach, Florida. 358 pp. Sherley, G. 2000. Invasive species in the Pacific: A technical review and draft regional strategy. South Pacific Regional Environment Programme, . 190 pp.

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Silvers, C. S., P. D. Pratt, A. P. Ferriter, and T. D. Center. 2007. T.A.M.E. Melaleuca: A regional approach for suppressing one of Florida's worst weeds. Journal of Aquatic Plant Management 45(JAN.):1-8. Singhurst, J. 2020. Melaleuca quinquenervia in Texas. Personal communication to A. Koop on May 11, 2020, from Jason Singhurst, Botanist, Texas Parks and Wildlife Department. Stablein, J. J., G. A. Bucholtz, and R. F. Lockey. 2002. Melaleuca tree and respiratory disease [Abstract]. Annals of Allergy, Asthma & Immunology 89(5):523-530. Starr, F., and K. Starr. 2020a. Starr and Starr Images. Starr Environmental. http://www.starrenvironmental.com/images/search/. Starr, F., and K. Starr. 2020b. Status of Melaleuca quinquenervia in Hawaii. Personal communication to A. Koop on May 4, 2020, from Forest and Kim Starr, Consultants, Starr Environmental. TAC. 2013. Rule §19.300 - Noxious and Invasive Plant List. Texas Administrative Code (TAC), Texas. Last accessed May 4, 2020, Tipping, P. W., M. R. Martin, K. R. Nimmo, R. M. Pierce, M. D. Smart, E. White, P. T. Madeira, and T. D. Center. 2009. Invasion of a West Everglades wetland by Melaleuca quinquenervia countered by classical biological control. Biological Control 48(1):73-78. Tipping, P. W., M. R. Martin, M. B. Rayamajhi, P. D. Pratt, and L. A. Gettys. 2018. Combining biological and mechanical tactics to suppress Melaleuca quinquenervia. Biological Control 121:229-233. Turner, C. E., T. D. Center, D. W. Burrows, and G. R. Buckingham. 1997. Ecology and management of Melaleuca quinquenervia, an invader of wetlands in Florida, USA. Wetlands Ecology and Management 5(3):165-178. UH. 2020. Weed risk assessments for Hawaii and Pacific Islands [Online Database]. University of Hawaii (UH). http://www.botany.hawaii.edu/faculty/daehler/wra/default2.htm. UNESCO. 2020. . United Nations Educational, Scientific, and Cultural Organization (UNESCO). Last accessed April 10, 2020, https://whc.unesco.org/en/list/76. USDA-ARS. 2018. Melaleuca quinquenervia (Melaleuca). United States Department of Agriculture, Agricultural Research Service, Ft. Lauderdale, Florida. Last accessed April 10, 2020, https://www.ars.usda.gov/southeast-area/fort-lauderdale-fl/iprl/docs/melaleuca-quinquenervia- melaleuca/. USFWS. 2008. 5-Year review for the endangered Viola helenae. United States Fish and Wildlife Service (USFWS), United States. 6 pp. Van, T. K., M. B. Rayachhetry, T. D. Center, and P. D. Pratt. 2002. Litter dynamics and phenology of Melaleuca quinquenervia in South Florida. Journal of Aquatic Plant Management 40(1):22-27. van Wyk, E. 2020. . South African National Biodiversity Institute, Pretoria, South Africa. Last accessed April 17, 2020, https://www.sanbi.org/resources/infobases/invasive-alien- plant-alert/melaleuca-ericifolia/. van Wyk, E., L. Jacobs, and J. Wilson. 2010. The value of context in early detection and rapid response decisions: Melaleuca invasions in South Africa. Pages 213-222 in S. Brunel, A. Uludag, E. Fernandez-Galiano, and G. Brundu (eds.). Proceedings of the 2nd International Workshop on Invasive Plants in the Mediterranean Type Regions of the World. Steering Committee, Trabzon, Turkey. Vardaman, S. M. 1994. The reproductive ecology of Melaleuca quinquenervia (Cav.) Blake. Master's Thesis, Florida International University, Miami, Florida. Wade, D., J. Ewel, and R. Hofstetter. 1980. Fire in South Florida ecoystems. United States Department of Agriculture, Forest Service, Southeastern Forest Experiment Station, Asheville, North Carolina. 125 pp.

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Wagner, W. L., D. R. Herbst, and S. H. Sohmer. 1999. Manual of the Flowering Plants of Hawai'i (Revised ed., vols 1 & 2). University of Hawaii Press & Bishop Museum Press, Honolulu, Hawaii, U.S.A. 1919 pp. Watt, M. S., D. J. Kriticos, and L. K. Manning. 2009. The current and future potential distribution of Melaleuca quinquenervia. Weed Research 49(4):381-390. Weston, M. ND. Melaleuca and fire: A growing menance [PowerPoint presentation]. Florida Department of Agriculture and Consumer Services, Florida Division of Forestry, Florida. 18 pp. Woodall, S. L. 1982. Seed dispersal in Melaleuca quinquenervia. Florida Scientist 45(2):81-93. Wunderlin, R. P., and P. F. Hansen. 2020. Atlas of Florida Vascular Plants. University of South Florida, Department of Biology, Institute for Systematic Botany. http://florida.plantatlas.usf.edu/Default.aspx.

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Appendix A. Weed risk assessment for Melaleuca quinquenervia (Cav.) S. T. Blake (Myrtaceae)

The following table includes the evidence and associated references that were used to evaluate the risk potential of this taxon. We also included the answer, uncertainty rating, and score for each question.

Question ID Answer - Score Notes (and references) Uncertainty ESTABLISHMENT/SPREAD POTENTIAL ES-1 [What is the taxon’s f - negl 5 Melaleuca quinquenervia is native to Australia, establishment and spread status , and New Caledonia (NGRP, outside its native range? (a) 2020). It has become naturalized in southern Introduced elsewhere =>75 Africa, India, the Philippines, Guyana, (NGRP, years ago but not escaped; (b) 2020), Madagascar (Kull et al., 2019; Introduced <75 years ago but Miandrimanana et al., 2014), and Puerto Rico not escaped; (c) Never moved (Pratt et al., 2005). In the Bahamas, it is currently beyond its native range; (d) naturalized but appears to be spreading as there Escaped/Casual; (e) are numerous juvenile trees on the periphery of Naturalized; (f) Invasive; (?) populations (Pratt et al., 2007). Melaleuca was Unknown] introduced into southern Florida in 1886 (Dray et al., 2006) and by 1994, had infested about 0.61 million hectares (Bodle et al., 1994 in Tipping et al., 2009). In southern Florida, it has invaded most types of terrestrial and aquatic communities, including those where the vegetation appears to be healthy (Serbesoff-King, 2003). Once the level of infestation in an area reaches 2 to 5 percent, it usually takes about 25 years for 95 percent infestation to occur (Laroche and Ferriter, 1992). The spread and infestation of melaleuca is best characterized by a logistic function, where there are three phases of growth and spread (Laroche and Ferriter, 1992). Alternate answers for the uncertainty simulation were both "e." ES-2 (Is the species highly n - negl 0 Although melaleuca has been cultivated for over a domesticated) hundred years (Dray et al., 2006; Neal, 1965; Page and Olds, 2001; Pratt et al., 2005), we found no evidence that it has been bred for reduced weediness potential (also cf. CABI, 2020). Furthermore, natural populations of this species are distributed throughout its native range in Australia (Balciunas et al., 1994). ES-3 (Significant weedy y - low 1 There are about 250 species in the congeners) Melaleuca (Mabberley, 2008). Randall (2017) provides evidence that about two dozen species have been identified to be weedy, but none of these appear to be significant weeds based on the number of supporting sources. In South Africa, an 80-hectare infestation of M. parvistaminea was detected in a forestry plantation and deemed high risk, resulting in the initiation of an Early Detection and Rapid Response program (Jacobs et al., 2014; van Wyk et al., 2010). It "grows along watercourses and seasonally inundated wetlands

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and will form dense thickets in wetlands. This poses a threat to water resources and water- dependent biodiversity and related ecosystem services" (van Wyk, 2020). Also, this species promotes fire (Jacobs et al., 2014). ES-4 (Shade tolerant at some y - negl 1 While mature trees are considered to be shade- stage of its life cycle) intolerant (Geary and Woodall, 1990), seedlings and juvenile trees < 10 cm at breast height can survive and grow within mature stands (Van et al., 2002). Furthermore, seeds don't need full sun to germinate (Serbesoff-King, 2003). ES-5 (Plant is a or n - negl 0 No, plant is a tree (Godfrey and Wooten, 1981). scrambling plant, or forms tightly appressed basal rosettes) ES-6 (Forms dense thickets, y - negl 2 It forms dense stands (Center et al., 2012; patches, or populations) Delnatte and Meyer, 2012; O'Hare and Dalrymple, 1997). A young population may have as many as 25 three-to-four meter tall trees in a square meter, but as the populations mature, density is reduced to about 0.5 12-meter tall trees per square meter (cited in Turner et al., 1997). ES-7 (Aquatic) n - negl 0 Although this species occurs in freshwater habitats (Dray et al., 2006) and has a root system that is well-adapted to periodic inundation (Serbesoff- King, 2003), it is not an obligate aquatic plant. This species is a large tree and can grow in terrestrial habitats (Dray et al., 2006). Mature trees and saplings can withstand prolonged periods of inundation (Pratt et al., 2005). ES-8 (Grass) n - negl 0 This species is not a grass. It is a tree in the Myrtaceae (NGRP, 2020). ES-9 (Nitrogen-fixing woody n - negl 0 We found no evidence that this species fixes plant) nitrogen. Furthermore, it is not in a plant family known to contain nitrogen-fixing species (Martin and Dowd, 1990; Santi et al., 2013). ES-10 (Does it produce viable y - negl 1 It reproduces through seed production (Gifford, seeds or spores) 1945; Serbesoff-King, 2003). ES-11 (Self-compatible or y - low 1 In Florida, it is self-compatible and autogamous, apomictic) though the species' flowering system promotes outcrossing (Vardaman, 1994 cited in Dray et al., 2009; Rayamajhi et al., 2002; Serbesoff-King, 2003). ES-12 (Requires specialist n - low 0 It is pollinated by insects, including bees pollinators) (cited in Serbesoff-King, 2003). ES-13 [What is the taxon’s b - mod 1 Melaleuca reproduces through seed production. In minimum generation time? (a) Florida, trees can begin flowering within a year of less than a year with multiple germination (Meskimen, 1962 cited in Center et al., generations per year; (b) 1 year, 2012) and may flower profusely within three years usually annuals; (c) 2 or 3 years; (Dray et al., 2006). We answered "b," but with (d) more than 3 years; or (?) moderate uncertainty because we could not obtain unknown] the original reference and because it is somewhat difficult to believe a woody tree species can flower within its first year. Answers for the uncertainty simulation were both "c."

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ES-14 (Prolific seed producer) y - negl 1 A single may produce 30 to 70 sessile seed capsules and each one contains an average of 264 seeds; approximately 7900 seeds per inflorescence. Given that trees flower profusely, a single twig could result in the production of over 500,000 seeds per year. "An individual tree may flower as many as five times per year and a given twig may flower three or more times per year (reviewed in Serbesoff-King, 2003). Usually 10 to 20 percent of seeds released from capsules germinate (cited in Laroche and Ferriter, 1992). From a six-month seed trap study, Woodall (1982) found there was a constant seed rain over this period and estimated that the average deposition of viable seeds to be about 301 - 339 per square meter per week. Thus over a single year, over 15,000 viable seeds per square meter would be deposited, exceeding the threshold of 1000 for this question. Another study, which examined seed deposition patterns over a 16-year period, found average seed fall to cover a range of 2,000 - 16,000 seeds per month (Rayamajhi et al., 2019). It is generally believed that constant propagule pressure has facilitated the extensive recruitment of this species into native plant communities (Tipping et al., 2009). The number of seeds in the canopies of 21-meter tall trees has been estimated to cover a range of 50 to 100 million seeds (Rayachhetry et al., 1998; Rayamajhi et al., 2002). ES-15 (Propagules likely to be y - high 1 We found conflicting information for this question. dispersed unintentionally by A Florida Department of Agriculture website notes people) that seeds may be dispersed by vehicles (FDACS, 2020), and a Hawaiian WRA answered yes to this question because it grows along roads (UH, 2020). CABI (CABI, 2020) does not list unintentional human dispersal as a dispersal mechanism, nor does a South African weed risk assessment (Jacobs et al., 2015). We answered yes with high uncertainty because there is ample opportunity for the small seeds to get transported on mud on vehicles. For example, in Florida this species occurs in rangelands, improved pastures, and other farmlands (Dray et al., 2006; Mazzotti et al., 1988; Silvers et al., 2007). Vehicles operating in these agricultural areas are likely to pick up seeds in the mud. Also, the use of an ATV in natural areas in Florida is a popular recreational activity (NPS, 2020). ATVs are often used in the same kinds of habitats that melaleuca invades, and are likely to get picked up in the mud and be transported to other sites.

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ES-16 (Propagules likely to n - high -1 We found no evidence for this type of dispersal. disperse in trade as Between 2002 and 2018, federal inspectors have contaminants or hitchhikers) intercepted M. quinquenervia and Melaleuca spp. eight times in personal baggage and in the mail. Most of those interceptions were for plant material for propagation (AQAS, 2020). Given the types of habitats melaleuca invades, it seems unlikely that it would come into contact with most agricultural goods. However, it is possible it could be transported in some landscape products such as pine straw, but we found no specific evidence of this. ES-17 (Number of natural 2 0 Fruit and seed traits for questions ES-17a through dispersal vectors) ES-17e: Melaleuca produces small, sessile woody capsules that contain small, wedge-shaped seeds that are about 0.5 to 1 mm in size (Godfrey and Wooten, 1981). They have variable sizes and shapes (Woodall, 1982). Seeds are released from capsules when fire, frost, wind breakage, natural pruning, or human activities such as herbicide application, girdling, etc., interrupt the continuity of the capsules' moisture supply, causing the walls to dry and dehisce (Woodall, 1982). Other than possibly flotation, seeds possess no obvious adaptation for dispersal (cited in Serbesoff-King, 2003). ES-17a (Wind dispersal) y - negl Most seeds fall from the tree within a short distance from the trunk, and have no obvious adaptation for wind dispersal, other than their small size (Woodall, 1982). Terminal velocity for seeds ranges between 0.6 and 1.8 m/s, while that of most wind-dispersed species is less than 0.3 m/s. A study examining seed terminal velocities, average wind speeds, and seeds caught in traps surrounding isolated trees estimated that in most cases, seeds would disperse no further than 170 m (Woodall, 1982). Although melaleuca seeds are heavier than most seeds of wind-dispersed species and have no specific adaptions for wind dispersal, we answered yes with negligible uncertainty because seed deposition patterns are clearly influenced by wind directions and could disperse seeds well-beyond canopy boundaries (Woodall, 1982). The ability of melaleuca populations to rapidly expand and fill in an area has been well documented (Laroche and Ferriter, 1992). In hurricane force winds, seeds may be dispersed as far as seven kilometers (cited in Serbesoff-King, 2003). ES-17b (Water dispersal) y - negl Seeds are dispersed by water (CABI, 2020; Wade et al., 1980). Newly fallen seed can resist wetting and rest on top of the surface tension of water for days (Laroche and Ferriter, 1992). They can also survive submersion in water for up to six months

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and still be viable to germinate. Seeds can also germinate in water or on the soil surface (Serbesoff-King, 2003). ES-17c (Bird dispersal) n - low A thorough review of the biology of this species did not find any evidence of this kind of dispersal (Serbesoff-King, 2003). ES-17d (Animal external n - mod A thorough review of the biology of this species did dispersal) not find any evidence of this kind of dispersal (Serbesoff-King, 2003). One website notes that seeds may be dispersed by small animals (FDACS, 2020). ES-17e (Animal internal n - low A thorough review of the biology of this species did dispersal) not find any evidence of this kind of dispersal (Serbesoff-King, 2003). ES-18 (Evidence that a y - negl 1 Melaleuca is able to hold seed capsules for several persistent (>1yr) propagule bank years on the tree, resulting in an aerial seed bank (seed bank) is formed) (Woodall, 1982). Seeds may remain viable in the capsules for several years (Laroche and Ferriter, 1992), and even the oldest capsules on a tree had an average germination rate of 15 percent (Laroche and Ferriter, 1992). Another study showed that of the viable seeds in a capsule, 27 percent of them did not germinate under greenhouse conditions suggesting there may be some underlying dormancy (Rayachhetry et al., 1998; Rayamajhi et al., 2002). Seeds can remain viable for at least 10 months and up to 2 years in the soil (Serbesoff-King, 2003). ES-19 (Tolerates/benefits from y - negl 1 Melaleuca has several traits that make it well- mutilation, cultivation or fire) adapted to periodic fire: 1) it has a thick, spongy bark that is well-saturated with water in the deeper layers and protects the cambium; 2) it has epicormic trunk bunds capable of sprouting new shoots; and 3) it also possesses serotinous fruit capsules that release seeds following fire (Turner et al., 1997). Adult trees that are damaged by fire re-sprout vigorously (Wade et al., 1980). Trees can also bloom a few weeks after a fire event (cited in Serbesoff-King, 2003). When disturbed by either fire, stem damage, or tree girdling, trees release seeds from their capsules, resulting in carpets of seedlings (Wade et al., 1980; Weston, ND). When stressed, a single tree may release as many as 20 million seeds at a time, which represents a big challenge for management (cited in Serbesoff- King, 2003). A large fire at one site in 1998 resulted in a major recruitment event where seedling densities exceeded 1000 per square meter (Tipping et al., 2009). Trees readily coppice if left untreated (Tipping et al., 2018). ES-20 (Is resistant to some n - negl 0 We found no evidence that this species is resistant herbicides or has the potential to to herbicides (e.g., Heap, 2020; Hutchinson et al., become resistant) 2007). The preferred method of controlling light to moderately infested tracts involves applying a

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solution of imazapyr and glyphosate at 25 percent each (Laroche and McKim, 2004). For large dense tracts, these same herbicides are applied aerially by helicopters (Laroche and McKim, 2004). ES-21 (Number of cold 5 0 hardiness zones suitable for its survival) ES-22 (Number of climate types 5 2 suitable for its survival) ES-23 (Number of precipitation 9 1 bands suitable for its survival) IMPACT POTENTIAL General Impacts Imp-G1 (Allelopathic) y - high 0.1 One study examined the allelopathic potential of melaleuca in two ways (Di Stefano and Fisher, 1983). First, the researchers used melaleuca leachates in a lab experiment to determine whether it affected the germination of pine and cypress seeds. Although their results were somewhat variable, they found some evidence indicating that the leachates decreased either germination or radicle length relative to controls. Second, the same authors conducted a greenhouse study where 1 to 2 month-old seedlings of pine and cypress were watered with leachates from older melaleuca seedlings whose pots were allowed to drain into the test pots. The authors found that the leachates generally reduced seedling growth and shoot and root biomass relative to controls; however, a mulch treatment with melaleuca leaves either had no effect or increased seedling growth. The authors also did the same greenhouse study on melaleuca seedlings; they found that both melaleuca leachates and mulch reduced the growth of melaleuca seedlings (Di Stefano and Fisher, 1983). This data suggests that melaleuca may have an allelopathic effect on native species. Without additional evidence, we answered “yes”, but with high uncertainty. Imp-G2 (Parasitic) n - negl 0 We found no evidence that this species is parasitic. Furthermore, it is not in a family known to contain parasitic species (Heide-Jorgensen, 2008; Nickrent, 2016). Impacts to Natural Systems Imp-N1 (Changes ecosystem y - negl 0.4 Melaleuca changes fuel conditions in invaded processes and parameters that habitats (Schmitz and Hofstetter, 1999). Compared affect other species) to fires in herb-dominated marshes, "fires in melaleuca forests burn at temperatures high enough to dry out and ignite surficial organic soils" (Schmitz and Hofstetter, 1999). Hotter fires in pine and cypress stands, can cause canopy fires that can kill native trees but minimally damage

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melaleuca, which then further promotes the invasion by melaleuca (Center et al., 2012; Tipping et al., 2009; Weston, ND). Melaleuca is also able to "alter soil topography through the accumulation of leaf litter in the absence of normal fire regimes" (Schmitz and Hofstetter, 1999). Soil accretion can potentially lead to shorter hydroperiods over extensive areas (Center et al., 2012; Mazzotti et al., 1988). Even if trees are removed, changes to soil profile and ground level remain, which makes it difficult to fully restore native plant communities (Center et al., 2012). Imp-N2 (Changes habitat y - negl 0.2 As melaleuca invades South Florida wetland structure) prairies, it first converts the prairies into savanna- like communities that are more structurally diverse, but eventually these are replaced by dense, closed-canopy forested wetlands with a sparse understory (O'Hare and Dalrymple, 1997). Dense melaleuca stands, especially in prairie marshes, are devoid of most ground cover plants due to the ability of these stands to block out sunlight (Schmitz and Hofstetter, 1999). As of 1994, it resulted in an estimated loss of 0.2 to 0.61 million hectares of native habitats out of a 3.04 million hectares surveyed (Bodle et al., 1994 cited in Serbesoff-King, 2003). Imp-N3 (Changes species y - negl 0.2 In Florida, melaleuca replaces native vegetation diversity) (Godfrey and Wooten, 1981), particularly in the genera Andropogon, Eragrostis, Eupatorium, Rhynchospora, , Panicum, Pluchea, Erianthus, and Setaria (Schmitz and Hofstetter, 1999). In the Bahamas, there is a negative correlation between native wetland plant species and melaleuca density (Pratt et al., 2007). In Madagascar, it forms monodominant forests with little diversity (Eppley et al., 2015). A 16-year Florida study that examined litterfall in a melaleuca forest, where biocontrol agents had established, showed that the proportion of melaleuca leaf litter decreased by 15 percent over the study period, while the non-melaleuca leaf litter increased by 81 percent (Rayamajhi et al., 2019). Thus, as the influence of melaleuca trees decreased, native species were able to return (Rayamajhi et al., 2019). As melaleuca invades wetland areas, it increases the structural diversity of habitats, resulting in an increase in some bird species (O'Hare and Dalrymple, 1997). Along a gradient of open wetland prairies to closed forests, the habitat became suitable to non-wetland species at a faster rate than it became unsuitable to wetland species. In dense melaleuca forests, fish communities and other species that depend on wetlands were much less abundant. Finally, while a similar diversity of

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herpetofauna occurred across all cover types, their abundances were lowest in the closed-canopy melaleuca habitats (O'Hare and Dalrymple, 1997). Imp-N4 (Is it likely to affect y - negl 0.1 Because of its ability to transform entire habitats federal Threatened and and replace native vegetation (see evidence in Endangered species?) Imp-N1 through Imp-N3), melaleuca poses a risk to rare and Threatened and Endangered species. In Hawaii, it poses a risk to the federally Endangered Viola helenae (USFWS, 2008). Melaleuca expansion into seasonal wetlands in the water conservation districts in southern Florida eliminates critical habitat for the U.S. Threatened wood stork (Mycteria americana) (Bancroft et al., 1992). In Madagascar, it is a threat to endemic plant species that grow in the Analalava Foulpointe forest (Miandrimanana et al., 2014). Imp-N5 (Is it likely to affect any y - negl 0.1 Florida and other portions of the southeastern globally outstanding United States are considered to be globally ecoregions?) outstanding ecoregions (Ricketts et al., 1999). Furthermore, Everglades National Park has been designated as a global heritage site by UNESCO (2020) for its unique biological and ecological diversity. Because melaleuca is able to invade and transform most types of habitats in southern Florida, it poses a significant threat to the ecological integrity of the ecosystem (Serbesoff- King, 2003; Turner et al., 1997). Imp-N6 [What is the taxon’s c - negl 0.6 Melaleuca is widely regarded as one of the most weed status in natural systems? harmful weeds of natural areas in Florida (Turner (a) Taxon not a weed; (b) taxon et al., 1997). In 1990, the Florida Exotic Pest Plant a weed but no evidence of Council and the South Florida Water Management control; (c) taxon a weed and District convened a special task force of land evidence of control efforts] managers, scientists, and others to develop a management plan (Laroche, 1999). Between 1988 and 1998, the melaleuca project had spent $25 million in control; 78 million stems had been treated and/or removed from the Florida Everglades (Laroche, 1999). In order to control this species, manual, cultural, herbicidal, and biological control techniques need to be integrated to effectively control it in natural areas (Schmitz and Hofstetter, 1999; Tipping et al., 2018). For manual and mechanical control of melaleuca stands, treatment costs range from about $1800 to $3700 per acre, depending on the specific control methods being used and the total biomass present (Laroche and McKim, 2004). Studies have shown that biocontrol agents effectively suppress melaleuca populations by increasing mortality of young trees and decreasing reproductive output of large trees (Tipping et al., 2009). In Madagascar, natural resource managers are seeking to find the best way to control this species (Miandrimanana et

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al., 2014). Alternate answers for the uncertainty simulation were both "b." Impact to Anthropogenic Systems (e.g., cities, suburbs, roadways) Imp-A1 (Negatively impacts y - negl 0.1 It readily colonizes areas that are disturbed by land personal property, human safety, clearing and development, resulting in new or public infrastructure) buildings being surrounded by melaleuca forests. These forests pose a fire hazard as they burn with great intensity and are difficult to control (Schmitz and Hofstetter, 1999). The Florida Division of Forestry recommends eliminating trees within 30 feet of homes and buildings, and to thin out nearby stands to lessen the risk of canopy fires (Weston, ND). Buildings that occur in tree stands are “exposed to a serious fire hazard” (Geary and Woodall, 1990). Imp-A2 (Changes or limits y - low 0.1 "An economic study commissioned by the Florida recreational use of an area) Department of Environmental Protection (DEP) stated that the unbridled spread of melaleuca would severely restrict use of south Florida’s parks and recreation areas by local residents and tourists. Potential losses to the local economy were estimated at about $168.6 million annually" (Diamond et al., 1991 in Mazzotti et al., 1988). A separate study by a graduate student showed that some survey respondents thought it reduced the recreational value of invaded lands (Finn, 2006). Imp-A3 (Affects desirable and n - low 0 We found no evidence of this impact. Because ornamental plants, and melaleuca proliferates in moist and wet habitats or vegetation) in disturbed or abandoned sites, it seems unlikely that it would have this impact, particularly when ornamental plants are located in areas that are regularly maintained. Consequently, we answered “no” with low uncertainty. Imp-A4 [What is the taxon’s c - low 0.4 Melaleuca is considered a weed and invasive plant weed status in anthropogenic of anthropogenic systems in South Florida systems? (a) Taxon not a weed; (Mazzotti et al., 1988; Silvers et al., 2007; Wade et (b) Taxon a weed but no al., 1980). In Maui, Hawaii, it is spreading in wet evidence of control; (c) Taxon a forests along the Hana Highway where road crews weed and evidence of control must continuously control it (Starr and Starr, efforts] 2020b). In Florida, “As dense stands of this species develop, south Florida resource managers are being faced, for the first time, with a vegetative type in which crown fires are common. Special safety procedures will be needed near urban areas and new fire prescriptions and control measures in rural areas" (Wade et al., 1980). The City of Ft. Lauderdale Florida has a policy to remove all trees from public property (City of Ft. Lauderdale, 2020). Both alternate answers were ‘b.’ Impact to Production Systems (agriculture, nurseries, forest plantations, orchards, etc.) Imp-P1 (Reduces crop/product y - low 0.4 Based on a 2003 survey on the impact of yield) melaleuca, agricultural managers in Florida reported that it reduced agricultural productivity by

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about 24 percent (Finn, 2006). In New Caledonia, where it is native, it takes over areas cleared for grazing (Blanfort and Orapa, 2008). Controlling it will improve cattle grazing areas (Silvers et al., 2007). Note that melaleuca is potentially beneficial for the bee industry as the trees help maintain wintering hives (Schmitz and Hofstetter, 1999). Imp-P2 (Lowers commodity n - mod 0 We found no evidence. value) Imp-P3 (Is it likely to impact n - mod 0 Melaleuca is regulated in , trade?) Mexico (APHIS, 2020), and South Africa (Department of Environmental Affairs, 2016). However, because we do not consider it likely to move in international trade (see evidence presented for ES-16) we answered no. Imp-P4 (Reduces the quality or n - mod 0 We found no specific evidence that it impacts availability of irrigation, or irrigation or that it strongly competes with plants for strongly competes with plants for water. The latter is not surprising given that the water) species prefers to grow in saturated soils, where water as a resource would not be limiting. We note that around 1937, seeds were dispersed over the eastern portion of the Florida Everglades to help drain the wetlands (Laroche and McKim, 2004). Imp-P5 (Toxic to animals, n - low 0 Although there is no significant herbivory of including livestock/range animals melaleuca by mammals or birds (Serbesoff-King, and poultry) 2003), we found no specific evidence that it is toxic to animals (e.g., Burrows and Tyrl, 2013). Imp-P6 [What is the taxon’s c - low 0.6 It is considered an agricultural weed of pastures in weed status in production New Caledonia (Blanfort and Orapa, 2008) and a systems? (a) Taxon not a weed; weed of agricultural systems in southern Florida (b) Taxon a weed but no (Silvers et al., 2007). A 2003 survey of agricultural evidence of control; (c) Taxon a managers showed that melaleuca was present on weed and evidence of control agricultural lands and that owners managed those efforts] populations to some extent using either mechanical or chemical methods, or a combination of the two (Finn, 2006). Seven percent of the survey respondents reported spending $244,000 on special equipment to control it (Finn, 2006). Alternate answers for the uncertainty simulation were both 'b.' GEOGRAPHIC POTENTIAL Unless otherwise indicated, the following evidence represents geographically referenced points obtained from the Global Biodiversity Information Facility (GBIF, 2020). Plant hardiness zones Geo-Z1 (Zone 1) n - negl N/A We found no evidence that it occurs in this hardiness zone. Geo-Z2 (Zone 2) n - negl N/A We found no evidence. Geo-Z3 (Zone 3) n - negl N/A We found no evidence. Geo-Z4 (Zone 4) n - negl N/A We found no evidence. Geo-Z5 (Zone 5) n - negl N/A We found no evidence. Geo-Z6 (Zone 6) n - negl N/A We found no evidence. Geo-Z7 (Zone 7) n - negl N/A We found no evidence.

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Geo-Z8 (Zone 8) n - high N/A Some points in Australia, but most are within 5 miles of Zone 9. Because winter freezes kill trees (Turner et al., 1997), we answered “no” with high uncertainty. Geo-Z9 (Zone 9) y - low N/A Australia. Florida (EDDMapS, 2020; GBIF, 2020). In Florida, it occurs from zones 9a to 10b (Serbesoff-King, 2003). Two points in South Africa. CABI reports that the absolute minimum temperature range is -3 to -1 °C (CABI, 2020). Serbesoff-King (2003) note that it is tolerant of infrequent frost and can recuperate from a significant freeze down to -5 °C and below 0 °C for a few hours (Serbesoff-King, 2003). Based on this evidence and additional horticultural information (Anderson, 2020; Doffitt, 2020; Hardy, 2020; SERNEC Data Portal, 2020), it appears that this species can grow in Zone 9. However, the information on minimum temperature and comments and observations about the impact of freezing temperatures on plants (Baldwin, 2020; Landry, 2020; Serbesoff-King, 2003), indicate that perhaps only the warmest temperatures of Zone 9 are suitable. As such, we answered “yes” but with low uncertainty to indicate that this zone is not fully suitable. Geo-Z10 (Zone 10) y - negl N/A Australia. Florida (EDDMapS, 2020; GBIF, 2020). In Florida, it occurs from zones 9a to 10b (Serbesoff-King, 2003) Geo-Z11 (Zone 11) y - negl N/A Florida (EDDMapS, 2020; GBIF, 2020). Some points in Australia. Some points in Madagascar. Geo-Z12 (Zone 12) y - negl N/A Australia. Some points in New Caledonia. Three points in Madagascar. Geo-Z13 (Zone 13) y - negl N/A Australia. Some points in New Caledonia. A few points in Papua New Guinea. Köppen -Geiger climate classes Geo-C1 (Tropical rainforest) y - negl N/A United States (southeastern Florida). Some points in New Caledonia. A few points in Papua New Guinea, Puerto Rico, Madagascar, and Central America. One point in Indonesia. Geo-C2 (Tropical savanna) y - negl N/A Australia. A few points in New Caledonia and Central America. Geo-C3 (Steppe) n - high N/A Two points in Australia, but one of these is close to tropical savanna, and the other may be in a protected spot. Consequently, we answered “no” with high uncertainty. Geo-C4 (Desert) n - mod N/A One point in Australia, but this is likely cultivated and watered. Geo-C5 (Mediterranean) y - high N/A A few points in Australia in and around the city of Perth where it is likely cultivated. A small naturalized population was discovered in a Mediterranean region of South Africa, but these were found in a moist mountain seep (Jacobs et al., 2015). It is cultivated in southern California

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(Baldwin, 2020; Kelch, 2020; Ritter, 2020). While this species can grow in Mediterranean climates, it appears to do so only under cultivation or in moist protected sites. Thus, we answered this question as “yes” but with high uncertainty. Geo-C6 (Humid subtropical) y - negl N/A Australia and the United States (Florida) Geo-C7 (Marine west coast) y - high N/A A few points in Australia. One point in South Africa. Geo-C8 (Humid cont. warm n - negl N/A We found no evidence that it occurs in this climate sum.) class. Geo-C9 (Humid cont. cool sum.) n - negl N/A We found no evidence. Geo-C10 (Subarctic) n - negl N/A We found no evidence. Geo-C11 (Tundra) n - negl N/A We found no evidence. Geo-C12 (Icecap) n - negl N/A We found no evidence. 10-inch annual precipitation bands Geo-R1 (0-10 inches; 0-25 cm) n - high N/A One point in southern California (cultivated). Two points on Maui HI, in a state park on a trail heading to an airport. Because Wagner et al. (1999) state that it has become naturalized in mesic forests in Hawaii, we answered this question as “no” with high uncertainty. . Geo-R2 (10-20 inches; 25-51 n - high N/A Several points around Los Angeles CA, all likely cm) cultivated. Two points in South Africa, a few miles from the next higher precipitation band. Two other points in South Africa, but it is like these are cultivated. Four points on the island of Maui HI, but Wagner et al. (1999) state that it has become naturalized in mesic forests in Hawaii. Because this species does not appear to naturally occur in this precipitation band, we answered this question as “no” with high uncertainty. Geo-R3 (20-30 inches; 51-76 y - high N/A One point each in South Africa, Puerto Rico, and cm) Mexico. Geo-R4 (30-40 inches; 76-102 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. Some points in New Caledonia. Three points in Madagascar. Geo-R5 (40-50 inches; 102-127 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. It is widely established throughout southern Florida which receives 40-90 inches of precipitation. Some points in New Caledonia. Geo-R6 (50-60 inches; 127-152 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. It is widely established throughout southern Florida which receives 40-90 inches of precipitation. Some points in New Caledonia. Two points in Madagascar. Geo-R7 (60-70 inches; 152-178 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. It is widely established throughout southern Florida which receives 40-90 inches of precipitation. Geo-R8 (70-80 inches; 178-203 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. It is

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widely established throughout southern Florida which receives 40-90 inches of precipitation. A few points in Honduras. Geo-R9 (80-90 inches; 203-229 y - negl N/A It is mostly distributed along the coast of Australia, cm) which receives 30-90 inches of precipitation. It is widely established throughout southern Florida which receives 40-90 inches of precipitation. One point in Madagascar. Geo-R10 (90-100 inches; 229- y - low N/A Four points in Papua New Guinea. A few points in 254 cm) Madagascar. Three points in Central America. Geo-R11 (100+ inches; 254+ y - low N/A Three points in Papua New Guinea. cm) ENTRY POTENTIAL Ent-1 (Plant already here) y - negl 1 Because M. quinquenervia is already naturalized in the United States, we did not evaluate its entry potential. Ent-2 (Plant proposed for entry, - N/A or entry is imminent ) Ent-3 [Human value & - N/A cultivation/trade status: (a) Neither cultivated or positively valued; (b) Not cultivated, but positively valued or potentially beneficial; (c) Cultivated, but no evidence of trade or resale; (d) Commercially cultivated or other evidence of trade or resale] Ent-4 (Entry as a contaminant) Ent-4a (Plant present in - N/A Canada, Mexico, Central America, the Caribbean or China ) Ent-4b (Contaminant of plant - N/A propagative material (except seeds)) Ent-4c (Contaminant of seeds - N/A for planting) Ent-4d (Contaminant of ballast - N/A water) Ent-4e (Contaminant of - N/A aquarium plants or other aquarium products) Ent-4f (Contaminant of - N/A landscape products) Ent-4g (Contaminant of - N/A containers, packing materials, trade goods, equipment or conveyances) Ent-4h (Contaminants of fruit, - N/A vegetables, or other products for consumption or processing) Ent-4i (Contaminant of some - N/A other pathway)

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Ent-5 (Likely to enter through - N/A natural dispersal)

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Appendix B. Additional images.

Figure B1. Top image: Interior of a Melaleuca forest is shown above (John M. Randall, The Nature Conservancy, Bugwood.org) Bottom image: A small population in the Florida Everglades (Randy Westbrooks, Invasive Plant Control, Inc., Bugwood.org).

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Figure B2. Top photo: Melaleuca stand is being treated with herbicides by helicopter in the Florida Everglades. Bottom photo: Crown fire in Melaleuca (Images by: Tony Pernas, USDI National Park Service, Bugwood.org)

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