Uso alternativo do solo como forma de recuperação de área degradada.

Abstract

The increasing degradation of the Amazon biome, especially due to intense deforestation in the state of Pará, consequently generating degraded areas and forest fragmentation, which leads to the emergence of secondary forests with different dynamics and diversity from the original forest, generating impacts on biodiversity. The objective of the study was to compare the floristic diversity of two forest fragments: SAFs and capoeira, as a way of recovering degraded areas. The study was conducted at Fattoria Piave, a 125h property located in the city of Igarapé-Açu / PA. For floristic and structural analysis of the two forest fragments, two censuses were carried out, the first in 2018 and the second in 2020 in SAFs and in capoeira the two areas have a size of 1 ha. Which was broken up into 100 plots of 100 m2 (10x10 m2) or forest plot (PF), where all the arboreal individuals that had a chest height circumference (CAP)> 15.7 cm were inventoried, using a measuring tape that in diameter the height of the chest (DBH) is equivalent to 5 cm, the height (h) of all individuals was estimated. In both treatments, 20 sub-plots of 50 m2 (5x10 m2) were allocated within the forest plot for the sample of juvenile tree individuals, where individuals with CAP> 7.8 cm and <15.7 cm were measured, and estimated height, within of these 20 subplots, it has a further 10 m2 (1x10 m2) subplot to sample the seedlings of the tree individuals, in which all individuals that had height> 30 cm and CAP <7.8 cm were calculated, using a measure tape. In the second census in 2020, there was an incorporation of new species and an accounting of the species that died in both treatments. Based on the field data, phytosociological variables were calculated, such as: density, dominance, frequency and sociological position, relative and absolute values for the evaluation of the species expanded importance value index (IVIA), species coverage value index (IVC), Shannon-Weaver diversity index (H'), Simpson dominance index (C), Pielou equitability index (J') and Jaccard similarity index, the mean annual periodic increase (IPMA) was necessary and the mortality rate of capoeira and SAFs species. The two forest fragments diametric distribution in the form of an “inverted J”, the Shannon-Weaver index (H') varied from 3.08 in 2018 to 3.03 in 2020 in capoeira and from 2.91 in 2018 to 2.83 in 2020 at SAFs, in both treatments the index was considered low, showing a medium diversity, the most expressive species in capoeira were Myrcia sylvatica, Myrciaria tenella, Myrcia bracteata, Tapirira guianensis, Attalea maripa, no longer SAFs were Jacaranda copaia, Acacia mangium, Lacistema pubescens, Myrcia sylvatica, Vismia guianensis. The mortality rate of capoeira was 10.7% higher compared to that of SAFs. However, both treatments have a high coverage value index, which constitutes soil covered by biomass, plants mainly of the middle and upper strata and can correlate with superficial and deep roots, facilitating water infiltration and nutrient cycling and reducing erosion. therefore recovering a degraded area, nevertheless these two forest fragments are still far from reaching the recovery of biodiversity.