Estimation of the LAI [leaf area index] in a cultivated maritime pine eco system starting with directional gap measurement of stands

Spatial and temporal variations of LAI (leaf area index) in managed stands of maritime pine (Pinus pinaster Ait.) were estimated from directional gap fraction measurements using the DEMON instrument. We show that crown cover generally has a regular spatial distribution. Under these conditions, the LAI can be correctly estimated by taking into account only one scale of foliage clumping, that of needles in a shoot. The studied stands, 20 years old or more, had summer LAI values between 2 and 4. Variation of LAI with age was small and accompanied by a reduction in crown leaf area density. The measurement system does not permit accurate monitoring of phenological changes in leaf area, which are relatively slight.