No abstract

This study is aimed to understand responses in growth rhythm to different climatic conditions of the widespread deciduous species Cedrela odorata. Our own research was conducted in Nova Iguaçu. Rio de Janeiro State, Brazil) and compared with literature data from Aripuanã. Mato Grosso State, Brazil), Manaus. Amazonas State, Brazil) and Barinas. Barinas State, Venezuela). Growth periodicity was evaluated through leaf phenological behavior and radial growth. In Nova Iguaçu, leaf phenology was monitored monthly and radial growth was evaluated by cambial histological analysis of samples collected in wet and dry seasons. In the other sites, the authors evaluated the growth rhythm by dendrometer bands. Growth always occurs in the wet season, even when there is no water deficit during the dry season. Thus, the species is considered conservative concerning the maintenance of growth seasonality. Nevertheless, C. odorata was able to change its growth period, following local seasonality of its different growth sites. Therefore we suggest caution when performing climate analysis from a chronology using trees that grow in different periods of the year.

The lack of specific research on the sequence of events that determine plant growth from meristem until wood formation represents a gap in the knowledge of growth dynamics in woody species. In this work, we surveyed published studies concerning cambial activity of Brazilian native species aiming at allowing the comparison of applied methods and obtained results. The annual cambial seasonality was observed in all the investigated species. Nevertheless, we found high heterogeneity in the used methodologies. As a result from this analysis, our opinion points to the need for standardizing sampling protocols and for discussing the suitability of experimental designs. This will help to define with greater precision the factors that determine the radial growth in the different tropical ecosystems.

Knowledge about growth rhythm and longevity of tropical trees is essential to understand life strategies of native species, and consequently, of forest remnants. This study aims to investigate the growth dynamics of Centrolobium robustum, a representative species from Atlantic Forest. For this purpose, radial growth was examined through tree rings and cambium analysis, from macroscopical, anatomical, and ultrastructural perspectives. The apical and radial stem growth was evaluated through leaf and cambium phenology, respectively. Leaf and cambium behaviors were associated with environmental seasonality. The results showed that the period of cell production and cambial development occurred in association with leaf expansion and during the wet, warm, and long-day season. Seasonality of cambial and leaf phenology in response to the environment determined the annual formation of tree rings, and it allowed to evaluate C. robustum growth rates and longevity. Species seasonality also responded to abnormal climatic events during the study period, which shows its sensitivity to environmental changes and represents a factor to be considered in the forest management programs.

Studies of cambial dynamics have been employed to investigate the growth behavior of trees. In these investigations, however, spatial variation in cambial rhythm within the stem is usually not taken into account. This study aims to evaluate the contribution of multiple sampling scales on the cambial dynamics of Cedrela odorata L. (Meliaceae) in different seasons. The effects of slope orientation were also tested. Samples were processed and analyzed with standard plant histology techniques. Data from multiple sampling scales were analyzed with nested ANOVA for each season, and the total variance was partitioned according to the fraction related to each scale. The main sources of variability were associated with the scale of tree and scales smaller than 1 cm. Radial growth was not significantly related to acclivity orientation. Thus, to obtain samples that represent total variability in cambial dynamics, it is preferable to increase the number of sampled trees; to take multiple samples from a few millimetres apart from each other, or to assess multiple histological sections. Samples on scales greater than a few centimetres apart should not be given priority.