ESTIMATING BIOMASS THROUGH TRANSFER-FUNCTIONS BASED ON SIMULATION-MODEL RESULTS - A CASE-STUDY FOR THE SAHEL

Current methods to estimate biomass as a basis for carrying capacity a nd secondary production include biomass measurements in the field, use of rainfall/biomass relations and simulation models. Each of the meth ods have their drawbacks. Collection of field data is laborious, rainf all/biomass relations lack precision and models, which simulate proces ses, are highly-demanding in input data, expertise and advanced equipm ent. An approach is presented to bridge the gap between those simulati on models and the need for more accuracy in simple biomass estimates a t less detailed scales. Transfer functions are developed using the res ults of a process-simulation model called SAHEL. The transfer function s allow estimation of the depth of wetting of the soil profile and per colation in relation to the water content at field capacity (pF 2.5), In comparison with simple rainfall-biomass relations, application of t ransfer functions allow more accuracy in estimating biomass production at a less detailed scale, With the transfer functions length of growi ng periods could be established more accurately, allowing for more pre cision in agro-ecological zoning methods.