Regeneração natural em clareiras após a colheita florestal na Amazônia Oriental.

Abstract

The forest restoration process, both in terms of richness and species diversity. The first chapter of the study evaluated the richness, diversity, similarity, and ecological groups of tree species from natural regeneration in logging clearings in different size classes of clearings. From the formation of clearings caused by logging in 2014, 40 clearings were randomly selected. The clearing areas were calculated by the ellipse function, using the length and width dimensions (larger and smaller diagonals). Within each clearing all seedlings with height ≥ 30 cm were identified by species by scientific nomenclature and measured total height (HT), neck height diameter (CAD), or breast height (DBH). Additionally, a label with numerical identification was fixed in each individual and the ecological group was classified. Each clearing was classified as small (area <100 m²), medium (area 100 m² - 200 m²) and large (area> 200 m²). In detail the abundance of the species Bagassa guianensis, Cecropias ssp., Jacaranda copaia, Pourouma guianensis, Scheffera morototoni, Schizolobium parahyba and Zanthoxylum ssp. The floristic composition, similarity, phytosociological composition and ecological groups in different sizes of clearing seedlings of natural regeneration of the year 2015 were analyzed. The existence of significant difference in density by clearing size was verified by ANOVA. The second chapter evaluated the effect of the application of post-harvest silvicultural treatments on the dynamics of natural regeneration in anthropogenic forest clearings in southeastern Pará. Among the selected clearings, four silvicultural treatments were randomly selected (T0 - witnesses no interference; T1- cutting vines; T2- cutting vines and undesirable species; T3- applying T2 and cutting species compete for space). Each treatment. Evaluations were performed in 2015, 2016 and 2017. Silvicultural treatments were applied in 2016. To analyze the dynamics, only individuals from 100 cm of total height were included. The analysis of the community forest dynamics in the different silvicultural treatments was performed. The eight most abundant species were analyzed in more detail. The existence of significant difference between the different silvicultural treatments was verified by ANOVA. In the sample universe 4,474 individuals were sampled distributed in 95 species, 72 genera and 29 families. The abundance of individuals and richness in the small, medium and large clearings were 7,722.6, 7,512,1 and 5,601 ind / ha and 54, 79 and 57 species, respectively. Small clearings had higher diversity indexes, Shannon-Wiener (3.08) and Pielou (0.78). Pioneer species had the highest densities in the three clearing size classes. In the small and medium clearings the shade tolerant ones presented the largest number of species, while in the large clearing were the light ones. Species Bagassa guianenses, Cecropias ssp, Jacaranda copaia, Pourouma guianensis, Scheffera morototoni, Schizolobium parahyba and Zanthoxylum ssp were the most abundant species in the three clearing classes, although the average clearings in the first year of evaluation stood out. For forest dynamics the survival and entry rates were not statistically different between silvicultural treatments in the period from 2015 to 2016 and 2016 to 2017, only in the entry rate between T1 and T3 in the period from 2016 to 2017. In the comparison of growth Among the treatments applied, until now the treatments presented similar responses, there was no effect of treatments on growth. Evaluation of natural regeneration is important to understand species dynamics in the area, biodiversity, forest restoration and maintenance of timber stocks for future harvests.