This is a pun on 'log'. Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits, so you'd definitely be dealing with literal wood logs, but 'log' also means to enter information to a system, like what you'd do if you had to log your time
If you work in a forestry company you will probably have to log your time .