If I manage to get not 'a' single tree, but plural 'trees' in the frame, I am guessing I am NOT gonna be all that close to them!
In olden days, cameras had to be focused manually, by eye or by scale... I still have a few, and the non-SLR's DO need you to work-out or guesstimate the focus distance to set on the scale, either with a range-finder or a tape measure or "Err, how many Estate cars could I park between ma and that tree?"
NOW, on a Medium-Format film camera, the 'sensor' size is around 6cm by 6cm.. the 'normal' angle lens length on that is about 75mm enter the crop factor.... you shrink the sensor to that of a 35mm film camera, 24mm x 36mm.... the normal angle lens is about 50mm.... shrink that sensor some more for an APS-C sized sensor, about 16x24mm, the normal angle lens is about 35mm..... B-U-T a 50mm lens is a 50mm lens, and it dont know and dont care what size of sensor is behind it.... it has a closest focus distance and a range of critical focus from there to infinity, regardless... A-N-D on shorter focal length lenses, both the close-focus limit and the range of critical focus before infinity, both tend to be closer to the camera....
So IF you are using a very small sensor camera, like a smart-phone or action cam, this is probably a non-issue.... my little action-cam has a sensor so small, that it has a mere 4.5mm lens, which is a fish-eye on my APS-C Digi-SLR... and with a focal length that short, the close focus distance and the range of critical focus is so small and so close to the camera, its effectively 'focus free'....
Same phenomena, is used on 'zone-focus' film campact cameras; where with a lens of just 35mm to give a not # 'so' wide angle of view, the near focus and range of critical focus is still so short that with a moderate, say f3.5 aperture, focus doesn't have to be very critical, and you can get away with perhaps just three overlapping settings, near, middle and far.......
If I picked up my Olympus XA2 zone-focus film compact..... it has three icons for each 'zone'; close focus denoted by a single person's head-and shoulders, middle distance, by two toilet door people, full length, and far distance by a mountain icon..... near focus is nominally 3-6 feet, middle 4feet to infinity, far, 20 feet to infinity.... fastest aperture is f3.5, and this is a 'full-frame' film-camera....
This suggests, to get more than just one tree in the frame, unless they are bonzia's! You are going to be using a more moderate wide-angle lens, and at something probably tending towards a 'far' focus distance, and even on a full-frame digital camera, you SHOULD be able to pretty much set the lens to 'manual focus', set the hyper-focal focus distance, and NOT have to worry about focusing the dang thing what-so-ever.....
Of course, what the hyper-foal distance will be, will depend on your exact camera and lens combo, as well as the aperture you select; BUT, it wont be far off the far end of the focus travel on the lens, even if the lens has no scale to go by.
For the suggested situation, this is probably how I would go about it, and just turn 'off' the AF, and set focus to something close to the end of the focus ring's travel. Or I might start checking the web for clues, depending on whether my intended lens had any sort of user focus scale... but I'd probably also be using an old manual focus lens... if not the camera it was native to, and I WOULD litterally just set it to 'hyper-focus', where even looking through the thing in the dark to compose the shot probably isn't all that accurate or critical!
Your call... how much of the technology in your hand do you want to be dependent on?
Focus at around 20 feet, keep aperture over say f-4 and you should be good to go, on almost any Digi-SLR, with any lens or zoom-setting, shorter than about 50mm.