  We have measured the spectral correlations and intensity statistics of random
lasing modes in weakly scattering systems, and compared them to those of the
amplified spontaneous emission spikes. Their dramatic differences revealed the
distinct physical mechanisms. We find that local excitation of a weakly
scattering system may greatly reduce the number of lasing modes even without
absorption outside the pumped region. The lasing modes can be very different
from the quasimodes of the passive system due to selective amplification of the
feedback from the scatterers within the local gain region.
