THE LIGHT INTERCEPTION INDEX - A POTENTIAL TOOL FOR ASSISTING IN VEGETATION MANAGEMENT DECISIONS

Light interception by vegetation canopies surrounding white spruce (Picea glauca (Moench) Voss) was studied for four different vegetation complexes on two sites near Prince George, British Columbia. Measurements of canopy percent cover and height, and canopy proximity to the tree, were combined to provide an index that could predict light interception by the canopy. Rates of foliage development of the different vegetation canopies studied had a significant effect on their degree of light interception over the growing season. Canopies dominated by fireweed (Epilobium angustifolium L.) developed foliage at a faster rate than canopies dominated by other species, especially those dominated by thimbleberry (Rubus parviflorus Nutt.). Understanding the light interception characteristics of different vegetation canopies along with crop tree light requirements should allow the use of the light interception index for assessing the severity of competition for light in young plantations.