Dinâmica da Floresta Ombrófila Mista Aluvial, análise estrutural, dendrocronológica e ecofisiológica de Zanthoxylum rhoifolium Lam

Abstract

The present study aimed to characterize the floristic composition and structure of an Alluvial Mixed Ombrophilous Forest fragment in the city of Guarapuava, PR; to evaluate the dynamics of the forest in the period from 2011 to 2017, as well as to evaluate the ecophysiological characteristics of the Zanthoxylum rhoifolium Lam species present in this fragment, in relation to the different levels of humidity and verify the morphometric and dendrochronological relationships of this species. For the floristic, phytosociological and forest dynamics assessments, 72 plots of 100 m² each were used. In 2017 the trees had the DBH remediated, being recorded the mortality and entry of new individuals. For the dendrochronological study of Z. rhoifolium, increment rolls of 37 individuals were collected with the Pressler test. The morphometric variables were measured in the same 37 individuals, the DBH, total height, crown insertion height and crown length were measured. For the analysis of the fluorescence, the portable fluorometer PAM-2500 (Portable Chlorophyll Fluorometer) was used, with slow kinetics and fast kinetics, in leaves previously adapted to the dark, in the four seasons of the year, between 2017 and 2018. There were 45 species in the study area, with the Shannon Diversity Index ranging from 2.14 in 2011 to 2.24 in 2017, reflecting the inclusion of Vernonanthura discolor (Spreng.) H. Rob. The most representative species were Gymnanthes klotzschiana Müll.Arg, with the highest values of density, dominance, frequency and, consequently, value of importance, in the two evaluations. The growth results of Z. rhoifolium obtained with the increment rolls correlated with precipitation, maximum temperature, minimum temperature and insolation, and showed a significant correlation with the precipitation. The individuals of Z. rhoifolium had a mean total height of 8.43 m and a mean DBH of 12.20 cm. The species exhibited a different behavior for chlorophyll a fluorescence emission in relation to humidity levels, and dry plants had higher levels of fluorescence and pigment contents in relation to humid environment plants.