The dependence of the relative population inversion in Er3+-doped fiber amplifiers (EDFAs) upon temperature and cross-sections, taking into account the amplified spontaneous emission (ASE), are investigated theoretically by the modified rate equation model for 980 and 1470 nm pumping conditions. For the temperature range from 0 to +/- 50 degrees C and at the different signal wavelengths, the temperature and cross section-dependent gain characteristics with respect to pump powers are also examined in detail for the both conditions. As a consequence, the dependence of the performance of EDFAs on temperature for 980 nm pumping is weaker than that for 1470 nm pumping, not only at room temperature but also at the temperature range from 0 to +/- 50 degrees C. However, the performance of EDFAs is more efficient at the pumping wavelength of 1470 nm than that of 980 nm for a wide range of temperature and higher-pump power levels. The results of this theoretical model are a good agreement with the experimental ones in the literature. (c) 2005 Elsevier B.V. All rights reserved.