非表示:
キーワード:
evergreen; deciduous; leaf shedding; leaf flush; flowering; fruiting; light measurements; floodplain forest; várzea; Amazonia; Brazil
要旨:
Amazonian várzea forests are seasonally flooded by whitewater rivers. Flood periods last up to 230 days every year. The aim of the present study was to analyze the vegetative phenology of six tree species and the extent to which the aquatic phase may represent an unfavorable period (‘physiological winter’) for the trees. Leaf amount on the trees was determined by measurements of light incidence using an integrating quantum photometer. The results show that there is a period of increased leaf loss during the aquatic phase, but timing of leaf shedding and of leaf flush, and the duration of the leafless period were not directly related to the time of highest water level. All species started to produce new leaves while they were still flooded. Leaf flush occurred several weeks to months before the end of the aquatic phase. For the species analyzed, there was no period of rest and stagnation of phenological and growth activities during the whole aquatic phase, indicating that flooding did not represent a high stress factor.
