Milda Norkutė University of Natural Resources and Applied Life Sciences Wien, 2012

1. Melaleuca quinquenervia in Florida Milda NorkutėUniversity of Natural Resources and Applied Life SciencesWien, 2012

2. Origin • Family: Myrtaceae • Natural occurance: east coast of Australia • Habitats: • Coastal wetlands; • Riparian zones and Brakish estuaries.

3. Biology • Flowering periods: fall and winter; • Single 10 m high tree can hold up to 20 million seeds; • Seeds viable up to 2.3 years in soil, 6 months in water

4. Addaptation to invasion • Massive release of seeds after stress or increased bark thickness; • Dormant, lateral epicormic trunk buds under thick, spongy bark resprouting after fire or injury; Photo: http://learnline.cdu.edu.au/units/sbi263/ecology/individual.html

5. Impact on ecosystems • Nominated as among 100 of the “World's Worst” invaders; • Historical spread 2850 ha/y; • Occupies at least 200,000 ha of wetlands; • Threat to Everglades, which is International Biosphere reserve, a World Heritage Reserve and a Wetland of international importance • Has invaded almost all types of communities in south Florida.

6. Impact on ecosystems • Alteration of fire regimes • Elevated soil • Changed water table depth and soil physiology • Reduced nutrient mineralization • Out-competed native vegetation and loss of biodiversity Photo: http://learnline.cdu.edu.au/units/sbi263/ecology/individual.html

7. Photo: http://www.ens-newswire.com/ens/nov2004/2004-11-02-01.html

8. Introduction history • Why was melaleuca introuced? • Attractive exotic plant; • Landscape architecture; • Timber; • Mosquito repellent; • Prevention from erosion of Everglades levees;

9. Picture source: Dray et al., 2006

10. Eradication measures • Integrated approach: mechanical, biological and chemical methods • Legislative measures: US Federal Noxios Weed list; Florida prohibited Aquatic Plant List (Class I)

11. Biological Control • Release of Oxyops vitiosa Pascoe in 1997 Source: United States Department of Agriculture, Agricultural Research Serive

12. Biological Control • Release of Boreioglycaspis melaleucacae Moore in 2002 Source: United States Department of Agriculture, Agricultural Research Service

13. Herbicide application • Individual tree treatments most cost-effective and environmentally sound; • Herbicide in use – imazapyr; • Labor intensive, costly and slow

14. Herbicide application • Aerial application of glyphosate; • Cheap, but adverse effects on non-target vegetation; • Useful for treatement of pure stands. Photo: http://www.ens-newswire.com/ens/nov2004/2004-11-02-01.html

15. Physical methods • Prescribed burning and flooding; • Tree felling and manual removal of saplings; • Mechanical removal with heavy equipment not appropriate for natural areas; • Stumps and damaged roots require herbicide application.

16. Photo: http://www.ens-newswire.com/ens/nov2004/2004-11-02-01.html

17. Costs • Restoring system to its former state difficult and may be economically impossible; • $25 million on control efforts from 1989 to 1999 • Costs on biological control agents become lower over long time; • Benefit-Cost Analysis in 2003: Benefits – $23.3 million, Costs - $13.2 million

18. Costs Average cost per acre of Melaleuca treated in dense stands. Source: Hodges and Evans, 2007.

19. Thank you for your attention! Photo: Jack Liddon