The ratio of transmitted near-infrared radiation to photosynthetically active radiation (PAR) increases in proportion to the adsorbed PAR in the canopy

Atsushi Kume, Kenlo N. Nasahara, Shin Nagai, Hiroyuki Muraoka

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

The daily total photosynthetically active radiation (400-700 nm, PAR) and near-infrared radiation (700-1000 nm, NIR) were measured in the understory beneath the canopy (PARt and NIRt) and above the canopy (PARi and NIRi) of a Japanese cool-temperate deciduous broad-leaved forest during the snow-free period (May to November). The integration of spectral radiation for NIR and that for PAR, and the daily integrations of instantaneous NIR and PAR, reduced the noises from the optical difference in spectrum and from canopy structure heterogeneity, sky condition and solar elevation. PARi/PARt was linearly related to NIRt/PARt (R2 = 0.96). The effect of cloudiness was negligible, because the fluctuation of NIRi/PARi was quite small regardless of season and weather conditions compared with the range of NIRt/PARt in the forest. The ratio of NIRt/PARt beneath the canopy was log-linearly related to the in situ leaf area index (LAI) with a wide range from 0 to 5.25 (R2 = 0.97). We conclude that seasonal changes in fAPAR (= 1 - PARt/PARi) and LAI of a canopy can be estimated with high accuracy by transmitted NIRt and PARt beneath the canopy.

Original languageEnglish
Pages (from-to)99-106
Number of pages8
JournalJournal of Plant Research
Volume124
Issue number1
DOIs
Publication statusPublished - Jan 2011

All Science Journal Classification (ASJC) codes

  • Plant Science

Fingerprint Dive into the research topics of 'The ratio of transmitted near-infrared radiation to photosynthetically active radiation (PAR) increases in proportion to the adsorbed PAR in the canopy'. Together they form a unique fingerprint.

Cite this