According to The State of Alabama you have a lot of freedom in the area of ATV Regulations. ATV's do not even need to be titled, of course just because it is not an ATV regulation does not mean that you shouldn't do so. In the sad event your ATV is stolen, you will have a much better chance for proof of ownership if you title your machine. There is great riding to be done all over Alabama just find out the ATV regulations and you are on the trail to enjoying them all.
If you wish to do so according to ATV regulations you may apply for a title and register your ATV. If you wish to title or register your ATV, your vehicle needs to meet the Federal and state safety, emissions and anti-theft standards. To determine if your vehicle abides by these ATV regulations read your Manufacturer's Statement of Origin. Having your ATV titled and registered will give you permission to ride on public roads and highways and provide you with a license plate and registration tag, very simple ATV regulations are in place in Alabama.
There is no age limitation in Alabama helmet laws. Even if these are not ATV regulations in this state doesn't mean that you should not follow all safety rules for your own protection. This state leaves a lot up to the ATVers own commonsense. Use yours and never let young riders on their ATVs unattended and always make sure all riders of ATVs wear their safety gear. This also holds true for riding in state parks and trails find out what the The ATV regulations are for that particular trail and stick to them.