Abstract
The relationship between reed ( Phragmites australis) live shoot biomass and the infrared (IR-800 nm)/red (R-680 nm) reflectance ratio was investigated in two south Swedish reed stands using a hand-held digital instrument with the sensors approximately 4 m above ground level. The best linear correlations ( r 2=0·85, 0·93) were achieved with measurements made early in the growing season (beginning of June), while correlations were poorer in August ( r 2=0·79, 0·45) for both lakes. Measurements made under windy conditions gave a better correlation if the sky was overcast rather than in full sunlight. Above a reed shoot biomass of 800–900 g DW m −2 the IR/R reflectance ratio was constant. Clonal differences (phenotype) did not seem to influence the biomass-reflectance relationship. For reed standing in water, the relationship between biomass and reflectance ratio showed a different slope early in the season (when vegetation cover was low) compared to a stand without free water. There was a marked phenological influence on the biomass-reflectance ratio relationship, probably caused by increased leaf area index, the yellowing of lower leaves and stems, and panicle development. Spectral reflectance measurements can give a good (±10%) estimate of the average shoot biomass in a reed stand, although such estimates are not reliable in highly productive stands late in the growing season.
Sign-in/Register to access full text options 
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
