Comparison of Differential Environmental Responses of Colliguaja odorifera

Abstract

Summary C. odorifera , a dominant species of Central Chile, presents a highly developed lateral superficial rooting and a moderately deep tap-root system. This shrub occurs on the wet and shady south-facing slopes and also on the sunny and more xeric north-facing slopes. Solar radiation, air and soil moisture are quite different on both slopes. Hence, plants respond according to their particular environmental conditions. Shrubs growing on north-facing slopes have a higher diurnal and seasonal water stress as compared with the ones observed on the south-facing shrubs. This stress is partially overcome by a stomatal closure in the morning, a more xeromorphic leaf structure and a significant reduction of leaf size. The lesser water stress on south-facing shrubs enables them to maintain an adequate water balance. This situation is reflected on an earlier, greater and longer vegetative growth period.