Shipping any wood to some countries (including Australia) requires that the wood be fumigated and be accompanied by a fumigation certificate for entry. Be sure to check the specific rules for the country you are shipping to by checking the customs information for that country.
If you are shipping a large and heavy item, it may be packaged on top of a wooden pallet. The pallet still counts as a shipping item and must adhere to the country-specific rules on shipping wood.