Post-fire dynamics of tree vegetation in forests with and without a history of selective logging in the Eastern Amazon.

Worldwide, forests are susceptible to fire. Forests with fire and selective logging interactions require monitoring and evaluation. This study evaluated the phytosociology and dynamics of tree vegetation in a disturbed forest (DF) and an undisturbed forest (UF) in selective logging areas affected by fire, in the Brazilian East Amazon. All trees with DBH ≥ 5 cm were measured and identified botanically in 93 plots (5 X 50 m) in the DF area and 58 plots (5 X 50 m) in the UF area, in 2010 (before logging), 2011, 2015 and 2017 (two years after the fire). Analysis of species and tree composition, diversity, similarity, mortality and recruitment were carried out. The fire affected the DF and UF areas in a similar proportion in terms of trees loss and basal area, intensifying the mortality rate. In the short term (2 years), the fire did not cause a significant reduction in species diversity, but there was a tendency towards a similarity loss in species composition in the area disturbed by logging. Subsequent assessments are necessary to understand the forest's recovery mechanisms.

Post-fire recovery of a dense ombrophylous forest in Amazon.

The fires that occur in the Amazon are as damaging as the deforestation is. There is a need for further long-term studies on dynamics of tree communities in forests affected by fires. In the present study we evaluated the dynamics of tree species, before and after an accidental fire that occurred in 1997 in an experimental area of terra firme forest in the Floresta Nacional do Tapajós, in western Pará State, Brazil. Approximately 3500 trees with diameter measured at 1.30 m above ground (DBH) ≥ 5 cm were botanically identified and measured in 12 permanent plots of 0.25 ha (50 m x 50 m), in 1983, 1987, 1989, 1995, 2008 and 2012. Analyses of survival, mortality and recruitment of trees were performed. The results showed that although the fire has increased the mortality and recruitment rates after 15 years, the highest mortality occurred on trees with smaller diameters (DBH < 30 cm), so the fire did not affect the survival of large trees in the long term, explaining why the reduction in density of living trees has not greatly influenced the decrease in basal area in the burned forest.