Mapping NPP for a Coniferous Forest in Southern Sweden using data from Terra/MODIS

Net primary production (NPP) is modeled for a coniferous forest in southern Sweden for 2001. The model is based on the light-use efficiency concept where NPP is calculated as a product of absorbed photosynthetically active radiation (APAR) and a lightuse efficiency factor (ε). APAR is estimated from the fraction of APAR (FAPAR) multiplied with the daily total amount of incoming PAR. FAPAR is obtained by linear transformation of 250 m NDVI from Terra/MODIS. Prior to the transformation, the NDVI has been seasonally adjusted by fitting local asymmetric Gauss functions to the time series. ε is modeled daily as a function of temperature, latitude and time. The model is evaluated against an NPP time series obtained from flux measurements of net ecosystem exchange (NEE) and measurements of respiration carried out simultaneously at the site (r = 0.78 for modeled and measured NPP). FAPAR is evaluated against measurements 2004.