Avaliação dos impactos da severidade de queimadas sobre a estrutura, composição florística e diversidade da regeneração natural lenhosa do Miombo do Parque Nacional de Gilé

Abstract

The natural regeneration of tree species is one of the most sensitive strata to the impacts of wildfires in the Miombo forest. Among the factors of the wildfire regime, that influence regeneration, wildfire severity stands out, directly affecting the post-fire restoration capacity of the vegetation. This study aimed to evaluate the influence of wildfire severity on the structure, floristic composition, and diversity of natural woody regeneration in the Miombo forest of Gilé National Park. The impacts of wildfire severity on vegetation were assessed based on the wildfire severity map for 2022, which was categorized into three classes: low, medium, and high severity. The three severity classes were used as sampling units, with 29 subplots established to assess established natural regeneration (5 ≤ DBH < 10 cm) in 10 × 10 m subplots, and non-established regeneration (DBH < 5 cm) in 5 × 5 m subplots. All living and dead individuals were recorded in the subplots, including their structural characteristics and origin. The analysis included structural variables (abundance, diameter, height, and basal area), richness, and diversity indices (Shannon, Simpson). The influence of fire severity, environmental factors, and anthropogenic activities on vegetation structure and composition was also analyzed. The results showed that fire severity significantly influences vegetation structure, with medium-severity fires favoring certain fire-tolerant species, while low-severity areas showed better performance of more sensitive species. Furthermore, it was found that fire severity, combined with temperature and soil type, negatively impacts forest structure, reducing the diameter, height, and basal area of trees. Floristic composition showed little variation in initial regeneration, but changes were observed in established regeneration under high severity. Species richness was higher in areas of low and medium severity, and reduced in areas of high severity. It is concluded that severe fires compromise the structure and diversity of natural regeneration, while moderate levels of severity can favor certain groups of species. Thus, controlled fire management is essential for the conservation and sustainability of miombo forests.