You can find the estimation of biomass and productivity in Savanna ecosystem in my uploaded papers Effect of fire on biomass and nutrient concentration of savanna ecosystems published in Vegetatio 1993. Attached is the same. Further, you can also download the papers from our Supervisor and Guide Professor J.S. Singh, BHU, Varanasi

Dear Mounir

You can use the following book: Bonham, C. D. 1989. Herbaceous biomass. In :

Measurements for Terrestrial Vegetation.John Wiley and Sons, New York.

Dear Dr. Mounir, 

Those following references could be helpful:

• Pastures monitoring and assessment methods ( book in french "Méthodes d'inventaire et d'évaluation des pâturages")  P.DONADIEU, 1984;
• Natural resources assessment and charting in arid and semi-arid area (field manual in french " Evaluation et cartographie des ressources naturelles en zones arides et semi-arides") C.FLORET et al., 1987.   

Dear Dr. Mounir, this work probably has things that can help you:

Sala, OE y Austin AT. Methods for estimating aboveground net primary production. 

http://en.agro.uba.ar/users/sala/pdfs/088-sala.pdf

You can estimate biomass by using dimensional parameters, i.e., canopy cover, length and width of diameters as has been done by Gholami Baghi et al. (2013). You can download the full pdf , Journal of Rangeland Science, 2013, Vol. 3, No. 4 Gholami Baghi et al.

You can use remote sensing techniques to get information on aboveground biomass and make measurements on large scales. For details see Mundava et al (2014). 

Remote sensing techniques have been used by Porter et al. (2014). They have developed regression models for estimating biomass yields using data from satellite and ground based remote sensing platforms in pasturelands of Montana.

Dear Gupta, Many thanks for these useful papers. Best, Mounir

Mounir 

See THOMSON, E.F., S.N. MIRZA, and J. AFZAL. 1998. Technical note: Predicting the components of aerial biomass of fourwing saltbush from shrub height and volume. Journal of Range Management 51:323-325.

may help ? 

Use to be plenty literature on the subject in the 1960-80 and work in Central Asia too by soviet scientists 

Rgds 

Gus