Fire feedbacks facilitate invasion of pine savannas by Brazilian pepper (Schinus terebinthifolius)

• Published in: The New phytologist Vol. 184; no. 2; pp. 365 - 375
• Main Authors: Stevens, Jens T., Beckage, Brian
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.10.2009; Blackwell Publishing; Blackwell Publishing Ltd
• Subjects: Anacardiaceae - physiology; Brazilian pepper; Burn units; cellular automata; disturbance regime; Ecological invasion; Ecosystem; Everglades; Fire ecology; fire suppression; Fires; Grassland fires; Models, Biological; Mortality; Peppers; pine rockland savanna; Pine trees; Pinus; Savannas; Schinus terebinthifolius; Temperature; United States; Vegetation; United States
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2009.02965.x

Fire disturbance can mediate the invasion of ecological communities by nonnative species. Nonnative plants that modify existing fire regimes may initiate a positive feedback that can facilitate their continued invasion. Fire-sensitive plants may successfully invade pyrogenic landscapes if they can inhibit fire in the landscape. Here, we investigated whether the invasive shrub Brazilian pepper (Schinus terebinthifolius) can initiate a fire-suppression feedback in a fire-dependent pine savanna ecosystem in the southeastern USA. We found that prescribed burns caused significant (30-45%) mortality of Brazilian pepper at low densities and that savannas with more frequent fires contained less Brazilian pepper. However, high densities of Brazilian pepper reduced fire temperature by up to 200°C, and experienced as much as 80% lower mortality. A cellular automaton model was used to demonstrate that frequent fire may control low-density populations, but that Brazilian pepper may reach a sufficient density during fire-free periods to initiate a positive feedback that reduces the frequency of fire and converts the savanna to an invasive-dominated forest.