Max, overall i think it's a good site. Pretty clean and simple. Some suggestions however:
The pictures I feel should be more tree-related. The photos of native plants is all good for a botany class or plant nursery sight, but you're a tree care company, so maybe pics of mulching around the trees, proper pruning cuts vs. improper, climbing shots, etc.. etc.. Just my inital thought when seeing. (Think about what the customer will think seeing those photos, and who you are targeting)
Also, I would again mess with the layout a bit, the photos border right up against the side of your layout, it looks a bit tacky... I would try to clean things up a bit to appear more professional. Maybe consider having your toolbar that is at the bottom of the web page moved to the top. When I loaded the page initially I didn't notice it for quite a while because it was below my field of vision on the computer.
Consider changing your font colors and styles on the other pages as well, all green is extremely monotonous, and makes the brain think, oh I don't really want to read that. But the same text with different colors fonts lends itself naturally to reading.
Those are just some suggestions. Don't take this negatively, I do like the sight but there's always room for improvement. Good luck!
ps. don't loose the pic of the girl and the chainsaw
jp