Here are some of my thoughts, Will--
The site is visually gorgeous and having said that, I found the text difficult to read due to the letters and sentences being a bit crammed. I see you used SquareSpace as your website design tool and it does a terrific job with images and clean layouts, and I think you can adjust the text spacing and perhaps enlarge it a little. People do tend to gravitate to pictures and video first, yet it is important to connect the visual with a message they can understand clearly, otherwise it is like a really clever TV commercial that people remember but can't recall what the product was.
It is kind of hard to tell what you really want to do, who your ideal client is. Sometimes I would guess that it was quasi-governmental agencies and sometimes municipal and forest services, sometimes larger tree care companies. That may be where the critique comes from about feeling like you'd be expensive. I had some difficulty as well in thinking how I would "find" you in the internet world as there isn't a consistent phrase that shakes out from the text you provide. Searching the internet relies on text because pictures are invisible to the search engines.
I think you might consider renaming "Gallery" to "Portfolio" since you have combined the photos with a description of the work being done. I would think that for the level of work you are pitching, you might want to add a more in-depth 'case study' or two that shows off your specialization in terms of working with unusual tree species, growing conditions, or whatever is truly unique about your expertise. Are you the
Red Adair of climbing arborists, tackling complex situations or solving difficult problems? Or is it more about the ecology of the tree canopy, forests and sustainability, sort of a Jane Goodall in climbing gear and chainsaw? Is is both? I think it may be both!
I think your personal story of how you chose to travel this path would be a compelling bit of reading for people, and may prove valuable in marketing yourself without trying to obviously market yourself.
Testimonials from those who have recruited you to work on a job is going to be valuable, too, especially fellow arborists if you are strictly subcontracting. A detailed LinkedIn profile wouldn't hurt, either, with a link to and from your website. You can do that in SquareSpace. I also see that you should be able to now link to a Google+ profile which might be also good to have, and where you can join some arborist communities that are worldwide--good way to network with tree care companies around the globe (I've seen a lot in the UK who like to share photos and stuff on "Tree Care -- Arboriculture" Community on Google+).
Hope this is helpful in one way or another. I would be interested in how you make out with SquareSpace, it is not one of my favorites for website design because you tend to be stuck with the functionality that company decides you should have and I find that limiting compared with Wordpress and other 'open source' platforms. I also thought it was wicked expensive, too!
Cheers!