Forage production monitoring system: parameterization of fPAR and RUE

GONZALO GRIGERA; MARTÍN OESTERHELD

Missoula MT, USA

Workshop; Global Vegetation Workshop 2006; 2006

University of Montana

With the aim of enhance management of grazing livestock production systems of the Pampas in Argentina, we developed a monitoring system that routinely estimates forage above-ground net primary production (ANPP) at the managerial unit level and with a monthly step. Farmers adopted the system as a managerial support tool and currently ~500,000 ha in 300 farms are being monitored. The system is based on the radiation use efficiency (RUE) logic. We derive the fraction of incident photosynthetically active radiation absorbed by the canopy (fPAR) from MODIS normalized difference vegetation index (NDVI). RUE was empirically estimated with ground ANPP estimates for the two principal forage resources of the region: upland sown pastures, and lowland naturalized pastures.   The objectives of this work are to evaluate (1) the suitability of fPAR-NDVI relationship with field data and (2) the relative response of RUE and absorbed PAR (APAR) to stresses regularly occurring in these systems.