First off before I really start looking further into it, I love this photo and it's hard me to find anything that needs fixing! The colors are vivid and the warmth of the sun is some really wonderful lighting! But as much as I love this and keep looking at the tree as the center point, I keep going to white out area that is distracting me from everything thing else as it is the brightest area in this photo. Maybe you should try upping the contrast some, upping the warmth *yellow toned*, and give it a little bit more saturation. Not only do I think that will help, it will make you look at the colors and note the white out spot and you can pay attention to the details I believe.
Vision-With this how it is already, it's totally frame worthy, regardless of the white out. I love that you caught the shadow of the tree and how it expands to the edge of your photo. I'm always on the look out for that because if the shadow is not caught in lighting's such as these, it makes it hard to look at the photo because I normally see half of a shadow which means half of a photo. But I'm very happy to see a full shadow of the tree!
Originality- Not often do I see a photo like this. It caught my eye immediately and I had to take a closer look. The detail in the tree is very good in focusing and the grass looks like you can reach out and touch it. The top of the tree looks like 3D to me, so vivid and it kind of moves with you as you move around the room.
Technique- Using your Nikon D3100 in ISO 100, was a brilliant thing. Most of the time I see people using 600 or more for a warm shot such as this. You definitely know how to use your camera and you made this photo regardless of the machine. You caught this at almost the golden hour of the day, but the impact before that hour still made it warm. I like it.
Impact- Overall, I have to say after my critique, I still love this photo and I am very happy you shared it with all of us deviant artists to see It's rare sight indeed and I could get lost happily in your photo.