LAI2000

LAI-2000 Plant Canopy Analyzer, commonly referred to as LAI-2000, is a portable optical instrument used to estimate leaf area index (LAI) and study canopy structure in vegetation. It operates on the gap fraction principle, assessing how much sky is obscured by leaves when viewed from beneath the canopy.

The device samples diffuse skylight from multiple zenith angles using a hemispherical sensor head that houses several photodiodes or detectors. By comparing light measurements taken beneath the canopy with reference measurements above the canopy, the instrument computes LAI through a logarithmic relationship related to light transmission and leaf distribution. The method is designed to minimize the influence of direct sunlight by focusing on diffuse radiation and is often used under overcast conditions.

Manufactured by LI-COR, the LAI-2000 is a handheld or field-deployable instrument. Its sensor head is mounted on a pole or carried by the user, enabling measurements at multiple locations within a stand or plot. Data are typically processed with accompanying software to produce LAI values and related metrics such as canopy openness.

Applications for the LAI-2000 span forestry, ecology, agronomy, and remote sensing. It is used to characterize vegetation structure, monitor seasonal changes in leaf area, support carbon and water cycle studies, and calibrate satellite or airborne vegetation indices.

Limitations include sensitivity to canopy clumping and horizontal heterogeneity, which can bias LAI estimates. Accurate results require appropriate measurement conditions (preferably diffuse light), representative sampling across the study area, and careful calibration. The LAI-2000 has been superseded in some contexts by newer models, but remains a widely cited tool in ecological canopy analysis.