The predominance of secondary forest-species in Brazilian subtropical forests highlights the importance of understanding the ecology of these taxa, and dendrochronology provides valuable information about the growth and climate response of tree species. The wide distribution of Alchornea triplinervia (Spreng.) Mull. Arg. (Euphorbiaceae), and the presence of growth rings in its wood, leds to its selection for this study. Samples were collected from 34 trees growing in rainy dense forest fragments in the cities of Blumenau and Brusque, in southern Brazil, and subjected to standard dendrochronological techniques. The local chronology spanned from 1889 to 2013 and the age of the trees ranged from 32 to 125 years. The mean age was 73 years and annual increment was 1.13 mm year À1 ; the diameter and age showed a weak correlation. The results suggest that A. triplinervia growth responded negatively to hot summers and increased rainfall in the previous spring and winter. The high perdiodicity trend characteristic of ENSO activity was reflected in wavelet power spectra of A. triplinervia chronology, affecting positively its growth after strong ENSO events . Negative influences occurred before 1970 during normal ENSO events. Also, there is evidence of the existence of a connection between Pacific and Atlantic sea surface temperatures influencing on tree growth.
O comportamento germinativo das espécies florestais nativas tem exigido atenção no meio científico, principalmente na obtenção de informações referentes às condições ideais de germinação e utilização em ambientes de restauração e recuperação de áreas degradadas. Dessa forma, o presente estudo teve como objetivo avaliar o efeito da idade das árvores matrizes de Vernonanthura discolor (Spreng.) H. Rob. (Asteraceae) sobre o poder germinativo e o índice da velocidade de germinação (IVG) de sementes submetidas a diferentes períodos de armazenamento. Foram selecionadas quatro árvores matrizes para a coleta de sementes, das quais duas de aspecto adultosenil (A1 e A2) e duas de aspecto adulto-jovem (B1 e B2). Foram avaliados o poder germinativo e o IVG com períodos de 30 e 75 dias de armazenamento. Nas sementes armazenadas por 30 dias, o percentual germinativo foi estatisticamente superior para as matrizes A, porém o IVG foi superior nas matrizes B. O experimento apontou que as espécies adulto-senis mostraram melhores condições de germinação, assim como que fatores associados a características fenológicas e maturidade das matrizes podem alterar a taxa germinativa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.