nity or group, which characterizes the mean rate of energy consumption in a community. Models 1 and 2 generate peaked distributions of biomass spectral density whereas Model 3 generates a flat distribution. In Model 4, the distributions of biomass spectral density and of abundance spectral density depend on the Lagrangian multipler (λ2). When λ2 tends to zero or equals zero, the distributions of biomass spectral density and of abundance spectral density correspond to those from Model 3. When λ2 has a large negative value, the biomass spectrum is similar to the empirical flat biomass spectrum organized in logarithmic size intervals. When λ2>0, the biomass spectral density increases with body mass and the distribution of abundance spectral density is an unimodal curve.