Climatic Periodicity, Phenology, and Cambium Activity in Tropical Dry Forest Trees

Abstract

The seasonal time course of vegetative phenology and cambium growth is compared for tree species from Central America and Asia growing in tropical climates with a long, severe dry season. Although the inhibition of plant growth by water stress is weH established, responses to seasonal drought vary widely among such trees, and their annual development is not weH synchronized by climatic seasonality. In deciduous trees growing at microsites with low soil moisture storage, phenology and cambium growth are weH correlated with each other and with seasonal rainfall, and most trees have distinct annual rings. Phenology and cambium growth are progressively uncoupled from climatic seasonality in brevideciduous and evergreen trees growing at microsites with large soil water reserves which buffer trees against seasonal drought and thus may prevent the formation of distinct annual rings. There is some experimental evidence conceming the control of growth initiation in apical meristems and the cambium, but little is known about the mechanisms which arrest growth and deterrnine qualitative changes in organ development and cambium cell differentiation.

Fenologia da copaíba (Copaifera langsdorffii Desf. -- Leguminosae, Caesalpinioideae) em uma floresta semidecídua no sudeste do Brasil

“…Entre os indivíduos que não perderam folhas neste período, vários estavam estabelecidos em áreas de baixadas ou próximos a locais mais úmidos (mata de brejo) onde provavelmente existe disponibilidade permanente de água e ausência de estresse hídrico. Borchert (1999) observou que as mudanças foliares são progressivamente mais independentes da sazonalidade climática à medida em que as árvores crescem em microambientes com maior suprimento de água no solo, o qual protegeria as plantas contra o estresse hídrico sazonal. LemosFilho & Mendonça-Filho (2000) investigando as relações entre estresse hídrico e eventos fenológicos numa floresta em Caratinga, MG, verificaram que para três espécies de leguminosas arbóreas estudadas a queda de folhas foi maior em locais mais secos da floresta.…”

Phenology of Woody Species Along the Climatic Gradient in West Tropical Africa

“…Periodic observations identified variations in leaf shedding, and band dendrometers were used to measure variations in trunk girths. Annual variations in cambial activity (Liming, 1957) and periods of water stress undergone by trees (Borchert, 1999) can be deduced from the latter. An important study was carried out in the semi-deciduous forest at Lamto (Guinean bioclimate) by Devineau (1984Devineau ( , 1991.…”

Reproductive phenology of an herbaceous-subshrub layer of a Savannah (Campo Sujo) in the Cerrado Biosphere Reserve I, Brazil

“…According to Borchert (1999), a prolonged dry period in a seasonal tropical climate is the main climatic determinant of the foliar phenology. According to Sarmiento (1984) the phenology of the herbaceous tropical Savannah grasses is determined by the seasonality of those ecosystems.…”