Dinâmica de crescimento radial de Ceiba speciosa (A. St.-Hil.) Ravenna em ambientes florestal e urbano no estado do Rio de Janeiro, Brasil: estrutura anatômica do câmbio e do lenho, dendrocronologia e dendroquímica

Abstract

Urban pollution is one of the most significant environmental problems of world, that threatens human and environmental health. Studies evaluating the impact of environmental pollution on tree species found changes in the structure and duration of cambium activity, in xylogenesis and consequently in the production and quality of the wood. In this context, the aim of this study was evaluate the impact of urban pollution on the cambial structure of Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae) and effect in the wood structure and wood formation. The elementary chemical concentrations wood samples and soil samples of the study sites were also evaluated. Two study sites were selected: a forest and another under urban pollution. The stem samples were collected with the Pressler probe and processed and analyzed according to the usual techniques of plant anatomy and dendrochronology. The chemicals present in the growth rings and soil samples were determined from the Energy Dispersive X-ray Fluorescence technique (EDXRF). The results showed significant differences in the cambium and the wood structure of trees located in the two study sites. In urban area, the cambium showed lower fusiform initial cells and enlargement of the radial initial clusters, future parenchyma rays. The results observed in the cambium were reflected in wood anatomy. In urban area, the trees showed the shorter vessels and fibers, and rays more frequent and with larger width. Regarding dynamics of radial growth, the trees of the urban site had higher growth rates since the early growth and showed lower ages. The trees of both sites reaching values similar accumulated increment with a difference of about 20 years of age. The correlation between the chronologies and climatic factors showed a positive association between radial growth and hot and rainy periods. However, it was observed an immediate response of urban trees in relation to these factors. On the soil of both sites were observed 16 chemical elements, including highly toxic heavy metals such as copper, nickel and lead. The urban site showed the ground lower concentration of essential elements for plant nutrition, such as potassium and manganese, and higher levels of heavy metals: chromium, copper and lead. Chemical analysis of growth rings revealed the presence of 11 chemical elements fixed in the wood of both sites, among which are brome and heavy metals, such as zinc, and rubidium. The accumulation of air pollutants from urbanization and urban climate dynamics, as rising temperatures and decreasing rainfall, directly influence plant physiology. These urban features are the main causes of the observed differences in growth dynamics and the accumulation of chemicals in theC. speciosaw