Good looking site man!
If you haven't already, learn to use google adwords.
Create or have your designer create pages for tree removal and tree trimming titled
"tree removal -insert main service city here - "
"tree trimming -insert main service city here - "
See if you can create a blog or have your designer start one. Make posts titled
"oak removal -insert main service city here -"
"maple tree trimming -insert main service city here -"
I built my business off the web and word of mouth from website customers. It's way cheaper then paper ads and easier to reach customers seeking your specific services. You have a great start with a clean, good looking site. All you have to do is get people to visit your site and it will sell for you.
Make sure you are on google maps, yahoo local, yelp, etc
Make an effort to tell your customers they can review your service on sites I listed above.
I should go to bed. Your site should help your business grow!