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assessment of the forest productivity like model based 
on biome types only (Whittaker and Likens, 1975), 
model utilising the meteorological parameters (Lieth, 
1973) and Forest BGC model (Running and Coughltan, 
1988). 
With the recent advances in remote sensing for 
ecological research the Production Efficiency Model 
approach has come up which takes into account the most 
versatile parameter of vegetation i.e. APAR. Thus, 
models utilising the direct relationship of APAR with 
satellite parameters seem to attract the most. The 
physical basis of these models is that the measurements 
of light interception by canopy can be related 
empirically to dry matter production over time to 
produce predictive models of productivity as a function 
of intercepted radiation. The relationship between dry 
matter production and intercepted radiation under 
relatively constant environmental conditions at a single 
site usually is linear (Monteith, 1972; Linder, 1985; 
Canned et cil., 1987). 
W(t) — 8 C p X<(tPabs) t 
Where, W (t) is the dry matter accumulation during time 
interval t, 8,p is the conversion efficiency of plant to 
convert light into dry matter and cp a b s is the absorbed 
photosynthetically active radiation during time interval t. 
Fig. 7. Approach for biomass estimation using remote sensing. (Statistical Sampling Technique)