Biochemical components of vegetation canopies, such as chlorophyll and nitrogen, are among the parameters controlling physiological processes and therefore essential for the characterization of these processes and their integration in hydrological or vegetation modeling.
AVIS (Airborne Visible/near Infrared imaging Spectrometer), built at the department for environmental sciences of the Ludwig-Maximilians-University Munich, is a cost-effective tool for environmental monitoring. Its spectral range lies between 550 and 1000nm and its multitemporal application enables observation of the development of chlorophyll and nitrogen content of plants throughout a vegetation period.
Twelve and nine airborne data sets were gathered between April and September 1999 and 2000 respectively from three maize fields in a test site south-west of Munich in the Bavarian Alpine foothills, Germany (48° 6’, 11° 17’ E). Weekly ground-based measurements of plant parameters (plant height, phenology, biomass, nitrogen content, chlorophyll content) during the vegetation periods provided data validation.
The chlorophyll and nitrogen content of the maize canopies were derived using the Chlorophyll Absorption Integral (CAI), which exhibited a high correlation with the chlorophyll content per area and the nitrogen content, both per area (g/m2) and in percentage of dry matter (nitrogen=%DM; chlorophyll=mg/g), during vegetative growth before emergence of the ear. The chlorophyll content per mass cannot be derived with the CAI, due to distinct variations of the chlorophyll per mass during plant growth caused by the low chilling tolerance of maize.
The mean field values and the spatial distribution of parameter values within one of the fields will be presented, demonstrating the capabilities of AVIS.