Why do Invasive Species Succeed?

Many things can change to allow for the invasion.  Healthy ecosystems with intact ecosystem processes are more resilient against invasions.

Natural controls are often absent (predators, parasites, diseases) therefore invasive plants can put energy into reproduction and growth

Changes include:

1. • Ecosystem fragmentation

   • Suppression of fire

   • Humans (residential sprawl, turf grass, industrial growth)

   • Climate change (changes to seasonal patterns)

   • Hydrology alteration

Some can regrow from plant parts

• “Plant Fragmentation” – Each fragment can grow into mature individual

Prolific seed production:

• Multiflora rose: 500,000 seeds /year

• Purple loosestrife: 2.7 million seeds produced per plant 

Effective Dispersal

• Spread by humans, wind, water, fur from animals, and birds

Many green up earlier and stay green longer

• capture sunlight, nutrients, water

• more photosynthesis

• more energy

• competitive edge

Display rapid vegetative growth, allowing establishment over large areas

• rhizomes (underground stems send shoots)

• root tips

• suckering