Theory 26/Temperate Forest/Understory invasion
Invasion Tips on Light
The claim
Invasive shrub dominance occurs above a threshold in canopy openness, so a thinned forest can be invaded without any change in propagule pressure.
01Mechanism
Shrubs need light to establish; below the threshold they persist but do not spread, above it they outgrow regeneration.
02Prediction
Invasion should track openness.
03Refutation
Invasion tracking propagule pressure would remove light.