  A full appreciation of the role played by gas metallicity (Z), star-formation
rate (SFR), and stellar mass is fundamental to understanding how galaxies form
and evolve. The connections between these three parameters at different
redshifts significantly affect galaxy evolution, and thus provide important
constraints for galaxy evolution models. Using data from the Sloan Digital Sky
Survey-Data Release 7 (SDSS-DR7) and the Galaxy and Mass Assembly (GAMA)
surveys we study the relationships and dependencies between SFR, Z, and stellar
mass, as well as the Fundamental Plane for star-forming galaxies. We combine
both surveys using volume-limited samples up to a redshift of z ~ 0.36. The
GAMA and SDSS surveys complement each other when analyzing the relationships
between SFR, Mass and Z. We present evidence for SFR and metallicity evolution
to z ~ 0.2. We study the dependencies between SFR, Mass, Z, and specific
star-formation rate (SSFR) on the M-Z, M-SFR, M-SSFR, Z-SFR, and Z-SSFR
relations, finding strong correlations between all. Based on those
dependencies, we propose a simple model that allows us to explain the different
behaviour observed between low and high mass galaxies. Finally, our analysis
allows us to confirm the existence of a Fundamental Plane, for which Mass=f(Z,
SFR) in star-forming galaxies.
