For the New South Wales State Emergency Service in Australia, it is sometimes hard to find a tree in a desert.
To practice falling trees, we dig a hole and put up a fence post instead. We use fence posts up to 30cm around and of various lengths. We place them into the hole with wedges for support and fell the post to a preset direction to hone chainsaw skills.
For cross-cutting, we use the same posts once they have been felled and place them on a saw horse to hone the cross-cutting skills.