Diameter and basal area increment of arboreal species from an Ombrophyllous Mixed Forest located at the south of Parana state in the period from 1979-2000

Abstract

This researd intend to study the diameter and basal area increment of the species from an Ombrophyllous Mixed Forest located in São João do Triunfo (Parana State - Brazil). Nine plots of 1 ha, first evaluated in 1979, were recovered and measured in 2000. In 1979, all trees with diameter (dbh) ≥ 20 cm were identified, numbered and had its dbh measured. In 2000, based on the same criteria, trees which had not been counted in 1979 were considered as ingrowth, the missing ones were considered dead. In 1979, the sample (9 ha) had 2,133 trees of 51 species. In 2000, the number of trees increased to 2,202 and the species to 55. The distribution of the diameter increment is bimodal and the individual basal area is unimodal of all species. In both cases, the distribution is skewed to the right. During the period between 1979-2000, regarding to the median of the arboreal trees, they increased 5,3 cm (0.25 cm/year) of the dbh and 0.02882 m2 (0.0014 m2/year of the basal area. The Nectandra megapotamica and Cedrela fissilis species showed the highest increments. On the other hand, Eugenia sp. and Allophylus edulis species showed the lowest increments. The trees increment changed due to the diameter size, vitality, sociological position and stem quality classes, being higher in classes which present averaged dbh (40 to 80 cm), better vitality, superior stratum and better quality stem. The forest aged during the studied period, for it presented a net growth in basal area of 45.3055 m2 (5.0339 m2/ha or 0.2397 m2/ha/year). This fact confirm that the forest still had available space to allow growth, therefore it was not full-stocked in 1979.