Persistent fire effect on forest dynamics and species composition of an old-growth tropical forest

Abstract

Aim of the study: To assess structure, recruitment and mortality rates of tree species over almost three decades, 14 years before and 15 years after a forest fire. Material and methods: All trees ≥ 5 cm in DBH were identified and measured in 12 permanent plots (50 m x 50 m), in 1983, 1987, 1989, 1995, 2008, and 2012 of a dense ombrophilous forest in Eastern Amazon, Brazil. The analyses were carried out including all sampled species and their ecological groups: shade-tolerant, light-demanding, and pioneer species. Treatments were compared through a Linear Mixed Effect Model. Main results: The 15-year post-fire period is not enough for the old-growth tropical forest to recover its pre-fire conditions of recruitment and mortality rates. The post-fire recruitment and mortality rates increased, mainly the recruitment of pioneer species (p-value < 0.05). Research highlights: In a period of 15 years after the occurrence of a surface fire, the old-growth tropical forest still has high recruitment rates of shade-tolerant and light-demanding species and high incidence of pioneer species, confirming the persistent fire effects on forest dynamics and species composition in this ecosystem. Keywords: pioneer tree species; species dynamics; forest resilience; Tapajós National Forest; Amazonian forests. Abbreviations used: DBH (diameter at 1.3 m from the ground); D (density); BA (basal area); EG (ecological group); ST (shade-tolerant); LD (light-demanding); Pi (pioneer); Ni (non-identified ecological group); MR (mortality rates); RR (recruitment rates); LMM (Linear Mixed Effect Model).