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Measuring Crown Characteristics Using LIDAR and Multi-Spectral Imagery

Foresters have long recognized the potential for remote sensing tools to assist in forest stand assessment. Spectral imagery has been used to create cover type maps, assess relative forest health, estimate leaf area index, measure crown closure and even estimate timber volume. A new tool being researched for forest stand assessment is LIDAR (LIght Detection And Ranging). Laser based systems can provide a 3-dimensional representation of the forest canopy structure as well as accurate digital elevation models of the terrain surface.

Our project involves an effort to combine the capabilities of both LIDAR and high-resolution multi-spectral imagery. Funding from a NASA Earth Science Applications Research Program grant will provide for LIDAR data acquisition and the development of image analysis techniques. Acquisition of multi-spectral imagery and development of approaches for fusing the LIDAR and spectral data is being funded through a grant from the Remote Sensing Technologies Center. The ultimate goal of the our study is to provide accurate estimates of leaf area index and stand volume in plantations of loblolly pine through remote sensing of crown and canopy characteristics.

LIDAR data will be used to provide direct estimates of tree heights, crown dimensions, and stem density. Mean leaf area per tree will be estimated through empirically derived relations expressing leaf area as a function of crown dimensions and canopy density. Mechanical beam principles will be employed to estimate mean stem diameter as a function of tree height, live crown ration, and mean tree leaf area.

Two sites are being used in this study. The first site is on Temple-Inland Corp. land in east Texas. This site was established in 1996 as part of a study investigating impacts of harvesting and site preparation methods on long-term loblolly pine productivity. The second site is located within the John W. Starr Memorial Forest on Mississippi State University school forest property in Mississippi. The Mississippi sites were established to study the effects of different genetic families and planting spacing on loblolly pine productivity.