  A set of kinetic equations is used to study equilibration of the anisotropic
quark-gluon plasma produced by decays of color flux tubes possibly created at
the very early stages of ultra-relativistic heavy-ion collisions. The decay
rates of the initial color fields are given by the Schwinger formula, and the
collision terms are treated in the relaxation-time approximation. By connecting
the relaxation time with viscosity we are able to study production and
thermalization processes in the plasma characterized by different values of the
ratio of the shear viscosity to entropy density, eta/s. For the lowest (KSS)
value of this ratio, 4 pi eta/s = 1, and realistic initial conditions for the
fields, the system approaches the viscous-hydrodynamics regime within 1-2 fm/c.
On the other hand, for larger values of the viscosity, 4 pi eta/s greater or
equal to 3, the collisions in the plasma become inefficient to destroy
collective phenomena which manifest themselves as oscillations of different
plasma parameters. The presence of such oscillations brings in differences
between the kinetic and hydrodynamic descriptions, which suggest that the
viscous-hydrodynamics approach after 1-2 fm/c is not complete if 4 pi eta/s is
greater or equal to 3 and should be extended to include dissipative phenomena
connected with color conductivity.
