The short answer is Yes, most forums without a moderator rarely succeed.
You will need to have a good think as to who will moderate the forum, think about the purpose of the forum.
Course trainers would be an obvious candidate or a subject matter expert would be good choices.
What can a moderator do?
So they can have a range of responsibilities that you may want them do below are a few suggestions:
answering questions
moving posts to appropriate threads
removing inappropriate posts
starting discussions
sharing interesting content
asking questions to prompt further discussions
encouraging conversations and prompting quieter users to bring them into the conversations
But you can chose what the moderator does.