Mapping LAI in a Norway spruce forest using airborne laser scanning

Svein Solberg*, Andreas Brunner, Kjersti Holt Hanssen, Holger Lange, Erik Næsset, Miina Rautiainen, Pauline Stenberg

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

117 Citations (Scopus)

Abstract

In this study we demonstrate how airborne laser scanning (ALS) can be applied to map effective leaf area index (LAIe) in a spruce forest, after being calibrated with ground based measurements. In 2003 and 2005, ALS data and field estimates of LAIe were acquired in a Norway spruce forest in SE Norway. We used LI-COR's LAI-2000® Plant canopy analyzer ("LAI-2000") and hemispherical images ("HI") for field based estimates of LAIe. ALS penetration rate calculated from first echoes and from first and last echoes was strongly related to field estimates of LAIe. We fitted regression models of LAIe against the log-transformed inverse of the ALS penetration rate, and in accordance with the Beer-Lambert law this produced a linear, no-intercept relationship. This was particularly the case for the LAI-2000, having R2 values > 0.9. The strongest relationship was obtained by selecting ALS data from within a circle around each plot with a radius of 0.75 times the tree height. We found a slight difference in the relationship for the two years, which can be attributed to the differences in the ALS acquisition settings. The relationship was valid across four age classes of trees representing different stages of stand development, except in one case with newly regenerated stands which most likely was an artifact. Using LAIe based on HI data produced weaker relationships with the ALS data. This was the case even when we simulated LAI-2000 measurements based on the HI data.

Original languageEnglish
Pages (from-to)2317-2327
Number of pages11
JournalRemote Sensing of Environment
Volume113
Issue number11
DOIs
Publication statusPublished - 16 Nov 2009
MoE publication typeA1 Journal article-refereed

Keywords

  • LAI
  • LIDAR
  • Norway spruce

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