Ecology and Biology of Melaleuca quinquenervia

Cheryl McCormick-RoteCenter for Aquatic and Invasive Plants

UF-IFASGainesville, Florida 32653

cheryl@ufl.edu

Background

Native range and introduction history

Distribution in FL (and beyond)

Native Range – NE Australia Host 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

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

30-70 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 dispersalHigh 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/m2

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. 1977

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, sparseecotones, 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/RPOST: 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!