Ecology and Biology of Melaleuca quinquenervia Cheryl McCormick-Rote Center for Aquatic and Invasive Plants UF-IFAS Gainesville, Florida

Background Native range and introduction history Distribution in FL (and beyond) Native Range – NE AustraliaHost Range – South of Okeechobee Regulatory status

About Melaleuca Related to “tea tree oil” species, M. alternifolia Large, evergreen tree up to 100’ tall Large tap root (similar to a carrot) Success in FL attributed to “climate matching”

Identifying Features

Tolerant & Resilient Soils Drought Flooding Nutrients Light Fire

Seasonal Patterns Flowers produced w/in 1 yr of germination Year-round; mostly fall-winter (Oct-March) Individual trees flower up to five times per year New Shoot growth Begins in mid winter; extends into spring Plant Mating Systems – “Monecious” Self-compatible & out-crossing; insect pollinated

Seed Production Massive seed production seed capsules/twig Average 264 seeds/capsule Over 500,000 seeds/twig/year! Why is this significant? 3x more than native range Contributes to rapid colonization High germination Release triggered by fire/girdling/stem damage

Seed Dispersal No adaptations to facilitate seed dispersal High germination of seeds floating – long distance Most fall close to parent tree – short distance Wind – Almost all disperse no farther than ~ 500’ Hurricane-force winds: ~ 11 miles No animal vectors (birds – exception?)

Seeds Everywhere… Continuous, light seed rain Mature stand: bi-weekly rain = ~2300 seeds/m 2 Aerial seed bank estimates: 100 million seeds! 15% embryos  62% viable  75% germinate ~ 7 million germinated = lots of saplings! High percentage of dormant seeds Germination Saturated soil (w/in 3 days) Optimum in full sun, but not required Can germinate underwater on soil Favors “Noisy hydroperiods” & wet conditions

Habitat Requirements Climate Warm, but tolerates infrequent frost Survived severe freeze in Jan Soils Flooded, saturated, and well-drained; also always or never flooded soils Acid sand, organic soils, alkaline marl, limestone Saline tolerant Low nutrient soils – deep tap root

Invaded Communities Virtually south FL upland/wetland communities Undisturbed pine flatwoods, disturbed sites, sawgrass marshes, cypress swamps, savannahs, mangroves, and wet prairies. Typically invades open-canopy forests, sparse ecotones, wetlands, and fire-damaged forests Xeric communities resistant, not immune Dense hammock communities – too shady

Population Dynamics MQ estab. in FL >> vigorous than in AUS No co-evolved natural enemies to check populations High-frequency FL fires and low areas + human disturbance  explosive growth! MQ infests wet marsh: structure/richness PRE: Low structural diversity (grasses dominate) Initial: Savannah: temp. increase in both S/R POST: Closed-canopy stand/sparse understory w/ low structural diversity and community richness.

Implications for Native Species Competitive superiority for resources Light: Dense stands inhibit understory dev. Nutrients: Tap roots exploit nutrients at water table Water: Same as above Soil Properties: Decomposition rate change Soil Fauna: Soil micro- and macroarthropod shift Fire: Frequency and intensity changes Wildlife: Foliage/biomass not utilized; birds roost

… Thank You!