The effects of fire frequency on leaf and bark flammability strategies in subtropical semi-humid evergreen broadleaved forests in China.

Lack of knowledge of plant flammability has impeded the understanding of ecological feedbacks between fire and vegetation. We measured flammability traits of 263 woody plant species in the subtropical semi-humid regions of China to identify plant flammability strategies and assess the impact of fire frequency on different plant flammability syndromes that were defined as combinations of flammability strategies of leaves and bark. The results indicated that 40.0%, 39.1% and 20.9% of woody plant species had hot-, fast- and low-flammable leaves, respectively, and 28.2%, 35.7% and 36.1% of species had hot-, fast- and low-flammable bark, respectively. Tree species (47.5%) had a higher percentage of flammability strategy separation between leaves and bark than large shrubs (19.7%) and shrub species (18.2%). Community-level evidence showed that species with fast- or hot-flammable leaves and bark may gain a notable advantage with repeated fires. Structural equation models indicated that more frequently burned forests were associated with infertile soil, shrub enrichment and lower species richness, subsequently leading to favour on flammable plant species. Thus, a positive feedback loop would be generated between the dominance of flammable species in the plant communities and fire frequency, fostering the characteristics of fire regimes in the semi-humid evergreen broadleaved forests.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.