There are some ideal choices of wood to make your yurt door from. In my workshop, I always use air dried oak for yurt doors keeping the boards to no more than 6.5” and allowing plenty of room in the tongue and groove for expansion. If you want to use wider boards I would recommend only using quarter sawn (boards cut at 90 degrees to the surface of the tree) to minimise the possibility of the boards ‘cupping’ and don't forget to still allow space in the tongue and groove. Oak also stands up very well against rot and wood beetle infestation.
Another very good choice would be Chestnut. Again air dried. Chestnut has very similar qualities to oak but is not subject to as much movement, it is however subject to shake (splits) so be sure to check the boards over carefully before buying. It is also excellent against rot and wood beetle infestation. Chestnut is the preferred wood for fence posts as it lasts for a long time in the ground.
If you are wanting a soft wood I would say Douglas Fir would be a good choice, it’s a very stable wood and one of the hardest of our native soft woods. The beautiful figuring in the wood can make for a very attractive yurt door but it can be susceptible to wood beetle infestation so keep a careful watch for any tell tale signs and treat immediately.
If you’re tempted to use ash (especially as you will probably have some left over after completing the frame) don’t forget that it will turn black if it is exposed to the elements so it’s really important to keep the door protected with a good quality oil or varnish at all times. The frame of course is protected from the elements being on the inside of the canvas, whereas the door isn’t. Any oils and varnishes that are applied will require maintenance to be sure they keep out any water. Ash can also be susceptible to wood beetle infestation.
Good luck with your door and don’t forget to send a photo when its finished and we’ll share it on here.