Leaf area index

Leaf area index (LAI) is a dimensionless quantity that characterizes plant canopies.

It is an important variable used to predict photosynthetic primary production, evapotranspiration and as a reference tool for crop growth.

Indirect methods measure canopy geometry or light extinction and relate it to LAI.

[10] Direct methods can be easily applied on deciduous species by collecting leaves during leaf fall in traps of certain area distributed below the canopy.

It is very difficult (and also unethical) to apply such destructive techniques in natural ecosystems, particularly in forests of evergreen tree species.

The LAI-2200 calculates LAI and other canopy structure attributes from solar radiation measurements made with a wide-angle optical sensor.

Such indirect methods, where LAI is calculated based upon observations of other variables (canopy geometry, light interception, leaf length and width,[13] etc.)

are generally faster, amenable to automation, and thereby allow for a larger number of spatial samples to be obtained.

The disadvantage of the direct method is that it is destructive, time consuming and expensive, especially if the study area is very large.