Plantation agriculture is a significant contributor to the economy of many countries in Southeast
Asia and the Pacific.
This paper examines the effects of the plantation canopy on the environment of the herbage
understorey and its capacity for growth. A logical model which provides a basis for discussing plant
adaptive changes to decreasing light levels is described. This model in a simplified form allows
calculations to be made of the potential growth of grass or legume under various light levels; several
examples are presented. Calculated growth rates of pasture are then compared with animal
requirements to help assess. in the first instance. what animal production potentially can be
supported. Finally, further research needs to provide inputs for this model are suggested.