Yes, to ensure public safety, entire parks or parts of parks are closed in the event of reduction burns or bushfires. This will include any affected walking tracks.
Tracks stay closed until they have been checked for dangerous tree limbs. Burnt bushland areas remain off limits until the vegetation is re-established.
Check with the park if the track you want to walk has been re-opened. Anyone planning camping or four-wheel drive access into national parks should also get the latest information from NPWS.