Abstract
The objective of this study was to determine whether leaf area index (LAI) in temperate mixed forests is best estimated using multiple-return airborne laser scanning (lidar) data or dual-band, single-pass interferometric synthetic aperture radar data (from GeoSAR) alone, or both in combination. In situ measurements of LAI were made using the LiCor LAI-2000 Plant Canopy Analyzer on 61 plots (21 hardwood, 36 pine, 4 mixed pine hardwood; stand age ranging from 12-164 years; mean height ranging from 0.4 to 41.2 m) in the Appomattox-Buckingham State Forest, Virginia, USA. Lidar distributional metrics were calculated for all returns and for ten one meter deep crown density slices (a new metric), five above and five below the mode of the vegetation returns for each plot. GeoSAR metrics were calculated from the X-band backscatter coefficients (four looks) as well as both X- and P-band interferometric heights and magnitudes for each plot. Lidar metrics alone explained 69% of the variability in LAI, while GeoSAR metrics alone explained 52%. However, combining the lidar and GeoSAR metrics increased the R2 to 0.77 with a CV-RMSE of 0.42. This study indicates the clear potential for X-band backscatter and interferometric height (both now available from spaceborne sensors), when combined with small-footprint lidar data, to improve LAI estimation in temperate mixed forests.
Highlights
Leaf area index (LAI) is an important canopy descriptor used to estimate growth and productivity in forest ecosystems
This study indicates the clear potential for X-band backscatter and interferometric height, when combined with small-footprint lidar data, to improve LAI estimation in temperate mixed forests
Mean leaf area index values estimated on the ground, for all forest types, were between 3.1 to 4.1 (Table 2)
Summary
Leaf area index (LAI) is an important canopy descriptor used to estimate growth and productivity in forest ecosystems. Watson [1] stated one of the early definitions of LAI as the total one-sided area of leaf tissue per unit of ground surface area. LAI is a dimensionless index that represents an important method to quantify the amount of photosynthesizing tissue in forests. Leaves are radiation receivers (depending on the amount of productive leaves and their specific surface area, they absorb between 80 to 90% of the light assimilated by forests). Leaves are the main photosynthesizing organ in forest stands, variations in leaf production and light interception are directly related to forests growth and development. LAI is a key variable that can be used to monitor current forest stand growth and has become a key explanatory variable for ecosystem process models
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call