REGENERAÇÃO NATURAL EM DIFERENTES FRAGMENTOS DE FLORESTA OMBRÓFILA MISTA NO ESTADO DO PARANÁ

Abstract

The objective of this study was to evaluate the natural regeneration of tree species in conserved forest fragments and in properties in the Mixed Ombrophilous Forest. The study was carried out in two distinct areas, both in the municipality of Fernandes Pinheiro, Parana state, one of them being Irati National Forest (FLONA), characterized as a preserved fragment and the other, forest fragments of small rural properties, being that in one of the fragments belonging to a property, there are areas of gaps from scientific research on sustainable selective management. Natural regeneration was evaluated by means of size classes in which plants with height from 0.3 m to 1.0 m were classified in Class I, height of 1.01 m to 3.0 m belonging to Class II and plants with height from 3.01 m up to 9.9 cm in diameter at breast height, belonging to Class III. The natural regeneration survey was carried out by means of the installation of permanent transects of 10 m in length and according to the size class, the individuals were sampled in plots of different size; for Class I, II and III, one meter, three and seven meters were established for each side of the transect, totaling 20, 60 and 140 m², respectively. For FLONA de Irati, for forest fragments of small rural properties and gaps areas, 13, 23 and seven sample units were installed, respectively. In the joint analysis of the data, were found 118 species belonging to 42 botanical families, in which the most representative family in number of individuals and richness of species was Myrtaceae; with respect to ecological groups, 45.7% of the individuals belong to the initial secondary group. In the sampling carried out in the FLONA of Irati, 65 species were found in which the Rubiaceae family was the one with the highest abundance of individuals and Myrtaceae the greatest species richness, with Coussarea/Rudgea with the highest natural regeneration potential and the Class I with the highest density of individuals (6923 ind.ha-1); in relation to the individuals of the tree communities, Araucaria angustifolia was the species with the highest IVI. In forest fragments of small rural properties, 99 species were found in which the family with the highest abundance of individuals and species richness was Myrtaceae, with Curitiba prismatica as the species with the highest potential for natural regeneration and Class I with the highest density of individuals (8652 ind.ha-1); in relation to the arboreal stratum, Araucaria angustifolia was also the species with the highest IVI. In the areas of gaps, 54 species were found where the Myrtaceae family presented greater abundance of individuals and species richness. The Jaccard similarity index indicated, in general, that there is no floristic similarity between the regenerative and arboreal regenerator in FLONA of Irati and in the forest fragments of small rural properties. In both areas the diametric distribution assumed the form of negative exponential or J-inverted. The cluster analysis using as a variable the relative density of the species found in FLONA of Irati and in the forest fragments of small rural properties, formed three groups, in which Group 1 consisted of 8 plots representing 22.3% of the grouping, Group 2 for 21 plots representing 58.3%, Group 3 for 7 plots representing 19.4%; the discriminant analysis showed that there were 94.4% of correct classification of the plots within the groups, having two poorly classified plots, in which the cluster analysis classified as belonging to Group 3 and the discriminant analysis indicated that these belong to Group 2. With the plots reclassified within the groups, a new discriminant analysis was performed obtaining 100% of correct classifications, with Group 1 Coussarea/Rudgea as the main discriminant species, Group 3, Curitiba prismatica and Group 2 did not obtain any species to discriminant it.