Time to extinguish the exotic flame: Lessons from the 2021 Cape Town fire

• Published in: South African journal of botany Vol. 184; pp. 1163 - 1173
• Main Authors: MacAlister, Dunja, Chimphango, Samson BM, Hattas, Dawood, Muasya, A Muthama
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2025
• Subjects: biodiversity; Climate change; Exotic species; flammability; indigenous species; infrastructure; introduced plants; Leaf flammability; Leaf functional traits; leaves; national parks; Native species; risk; South Africa; species; specific leaf area; surface area; vegetation; Wildfire; wildfires; South Africa; Leaf flammability; Climate change; Exotic species; Leaf functional traits; Wildfire; Native species
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2025.07.026

•Leaf traits and flammability differences are strongly associated with plant origin.•Species that burned were associated with higher combustibility and SLA.•Exotic species, such as Phoenix canariensis, exhibit highly flammable leaf traits.•Thinner leaves and higher SLA were associated with faster ignition times.•Leaves with more surface area were associated with higher combustibility. Wildfire risk is increasing globally, particularly in Mediterranean-type ecosystems, due to climate change and the proliferation of flammable exotic plant species. A wildfire in April 2021 started on the slopes of Table Mountain National Park, South Africa, causing extensive destruction to the surrounding areas. This study examined how leaf functional and flammability traits influence flammability in native and exotic species within an urban setting in Cape Town, South Africa. Forty-two species (22 native, 20 exotic) were assessed for leaf functional traits and key flammability components: ignitibility, sustainability, and combustibility. Results showed that exotic species generally ignited faster and exhibited higher combustibility than native species. Conversely, native species tended to burn longer but at lower intensities. Leaf functional traits such as thickness, specific leaf area, and leaf surface area were significantly correlated with flammability measures. Exotic plants were particularly flammable due to traits like large leaf surface area, higher specific leaf area and thin leaves. Further results show that plants that burned in the 2021 fire were mainly associated with combustibility and moderate ignitibility, while those that partially burned tended to have thicker leaves, and those that didn’t burn were associated with longer ignition times. The findings emphasize the critical role of some exotic ornamental plants in increasing fire risk in urban areas. These results advocate for fire-conscious urban landscaping that prioritizes native, low flammability species to mitigate the spread of wildfires. As climate-driven fire regimes intensify, proactive vegetation management in urban zones will be essential to reduce fire hazards and protect infrastructure and biodiversity.