Cable logging is a way of logging steep slopes.  There are various ways of doing it, but essentially logs are attached to cables and winched off the ground up the hill to a de-branching area and/or down the hill to a yarding area. You can see the cable tower on the right below. It allows logging steep and fragile slopes.  Of which NZ has a lot.  Makes a bit of a mess of the hillsides, and allows pine trees – introduced species – to spread into the native forest.

In the Marlborough sounds they are trying to remove the pine trees by felling and poisoning, hence the dead pines on some of the slopes.