DENDROECOLOGICAL ANALYSIS OF Ocotea pulchella AND Nectandra maegapotamica ON TWO SITES NEAR SANTA MARIA, RIO GRANDE DO SUL (BRAZIL)

Abstract

A dendroecological analysis of Ocotea pulchella (n=5) and Nectandra megapotamica (n=2) was conducted on two sites near Santa Maria, Rio Grande do Sul (Brazil). Growth data were obtained by tree-ring analysis of stem disks at breast height (1,3 m). Radial increment was measured on four perpendicular radii using the 'LINTAB' measuring device. Mean growth sequences were standardised to highlight short-term variation. Air temperature, precipitation and compound climatic quantities like evapotranspiration and water balance were used to find indications about the climate-growth relationship. Variation of wood increment and climatic variation was compared by using sensitivity and correlation analysis. Some factors as regional climate (seasonality) in general, wood structure of the species and cross-dating of individual radii indicate that annual growth banding is likely. Due to a lacking correspondence between water balance and ring width indexes, water stress does not seem to be the synchronising factor of radial increment. In view of the measured periodical radial increments, it becomes evident that for Ocotea goal-diameters of 50-60 cm at breast height cannot be obtained in a short time without thinning. No medium-term growth release was found for both species.