Basically sunlight comes from one direction, so all the shadows fall the same way. So you might think that all you need to do is put up o e light and that's the job done. But often what happens is that you get deep shadows and can't see detail in them. So you can add a reflector board - which is just a piece of white board that reflects the light back . You have to fiddle around to get it at the right angle and distance from the set, but if you do it well it won't cast any backward shadows. Put it in and out quickly to see the difference it makes.
Another tool that will make the sunlight look really good is to use a cello cucoloris. They are usually called cookies, and the fancy name is just the proper term for a patterned flag with holes I it that creates a pattern of light. Easiest example is shutter shadows, or perhaps the shadow created by a window frame. For a forest you need dappled light, so you can make a cello cucoloris by taking some metal mesh and adding silicone to it in a pattern (look them up online) to create the dappled effect. You then mount it in front of the light. Alternative method is to draw the patterning Photoshop and photocopy it onto a sheet of acetate, such as used for overhead projectors. This will need some sort of mount.
Have a look at this video to see what I mean https://m.youtube.com/watch?v=eQSgbHzw3Rk&t=299s