  We present a survey of lithium abundances in 185 main- sequence field stars
with Teff between 5600 and 6600 K and [Fe/H] from -1.4 to +0.2 based on
high-resolution spectra of 130 stars and a reanalysis of data from Lambert et
al. (1991). The survey takes advantage of improved ways of determining
effective temperature, metallicity, mass and age, offering an opportunity to
investigate the behaviour of Li as a function of these parameters. An
interesting result is the presence of a large gap in the Li-Teff plane, which
distinguishes `Hyades-like, Li-dip' stars from other stars. These Li-dip stars
have a well-defined mass, which decreases with metallicity. Stars above the
gap, when divided into four metallicity groups, may show a correlation between
Li abundance and stellar mass, but with a large dispersion that cannot be
explained by observational errors or differences in metallicity and age, which
ranges from 1.5 to 15 Gyr. This suggests that Li depletion occurs early in
stellar life and that other parameters, e.g. initial rotation velocity and/or
the rate of angular momentum loss, affect the degree of depletion. A comparison
of the distribution of stars in the Li-[Fe/H] plane with evolutionary models of
Romano et al. (1999) suggests that novae are a major source for the Li
production in the Galactic disk.
