Leaf Area Index (LAI) is one of the most widely used measurements for describing plant canopy structure. LAI is also useful for understanding canopy function because many of the biosphere-atmosphere exchanges of mass and energy occur at the leaf surface. For these reasons, LAI is often a key biophysical variable used in biogeochemical, hydrological, and ecological models. LAI is also commonly used as a measure of crop and forest growth and productivity at spatial scales ranging from the plot to the globe.
In the past, measuring LAI was difficult and time consuming. However, theory and technology developed in recent years have made measuring LAI much simpler and more feasible for a wide range of canopies. Download this application guide for a brief introduction to the theory and instruments used to measure LAI. Several scenarios and special considerations are discussed, which will help individuals choose and apply the most appropriate method for their research needs. Below is a list of topics covered.
- What is LAI?
- How to measure LAI
- Direct measurement
- Indirect measurement
- Hemispherical photography
- Radiation transmittance
- Radiation reflectance
- Using the LP-80 ceptometer to measure LAI
- Short canopies
- Tall canopies
- Clumping and spatial sampling
- Atmospheric conditions
- Influence of non-photosynthetic elements
- Using the SRS-NDVI sensor to measure LAI
- Developing field-based NDVI-LAI regression models
- SRS-NDVI sampling considerations
- Influence of soil background on NDVI measurements
- Dealing with NDVI saturation in high LAI canopies