Out of steady state: Tracking canopy gap dynamics across Brazilian Amazon

Canopy gaps are evidence of disturbances on forest landscapes. A forest stand is in constant flux, with long stretches of biomass accumulation punctuated by episodic disturbances. We used multitemporal airborne laser scanning data to compare the gap dynamics of four Amazon forest sites. We assessed gap dynamics over 1.9–3.8 years between 2017 and 2020 at sites in the central, central eastern, southeastern, and northeastern regions of the Brazilian Amazon, over areas ranging from 590 to 1205 ha at each site. Gap size ranged from a minimum of 10 m2 to a maximum of about 10,000 m2. We analyzed four stages of gap dynamics: formation, expansion, persistence, and recovery based on two consecutive airborne laser scanning surveys. The gap fraction at our study sites varied between 1.26% and 7.84%. All the sites have similar proportion of gaps among gap size classes. What notably differed among sites was not the gap size‐distribution, but the relative importance of stages of gap dynamics. Expansion and persistence rates ranged from 12 to 118 m2 ha−1. The gap formation rate (formation + expansion) was lower than the recovery rate for three of the four study sites. In contrast, the southeastern site has 1.44 times more area in formation and expansion compared to gap recovery. Over the 2–4 years interval of our study, no site was close to steady state. Multitemporal analyses of large areas over many years are needed to improve our understanding of tropical forest dynamics. Resumo As clareiras são evidências de distúrbios em paisagens florestais. A floresta está em constante mudança, com longos períodos de acúmulo de biomassa interrompidos por distúrbios episódicos. Usamos dados multitemporais de levantamento laser aerotransportado para comparar a dinâmica de clareiras de quatro sítios na Amazônia, ao longo de 1,9 a 3,8 anos, entre 2017 e 2020. Os sítios estavam localizados nas regiões central, centro‐leste, sudeste e nordeste da Amazônia brasileira, com áreas variando de 590 a 1205 ha. O tamanho das clareiras estudadas variou entre o mínimo de 10 m2 a um máximo de aproximadamente 10.000 m2. Analisamos quatro estágios da dinâmica de clareiras: formação, expansão, persistência e recuperação a partir de dois levantamentos laser aerotransportado consecutivos. A fração de clareiras em nossos locais de estudo variou entre 1,26% e 7,84%. Todos os locais apresentaram proporção semelhante de clareiras entre as classes de tamanho. O que diferiu notavelmente entre os locais não