Leaf acclimation strategies to contrasting light conditions in saplings of different shade tolerance in a tropical cloud forest.

To study the acclimation responses of the leaves of saplings of six tree species when changed to low or high levels of irradiance, we carried out a light exposure experiment. Species representative of contrasting shade tolerance groups were identified across a light gradient in the understorey of a Venezuelan Andean cloud forest. Measured traits included gas exchange, chlorophyll fluorescence, and morphoanatomical, biochemical and optical properties.

[Light environment in the understory of an Andean cloud forest: canopy structure and climatic seasonality].

The light environment in the understory of cloud forests is highly heterogeneous and determined by species composition, canopy structure, site conditions, and seasonality. This study was carried out at San Eusebio cloud forest, Venezuela (2 300 - 2 500 masl). The impact of canopy structure variations on understory light availability was estimated in the dry (December-February) and rainy (March-November) seasons, in sites under continuous canopy cover and gaps of various sizes.