Not true!! I was assured by the Attorney General's staff that Landscapers and Tree Companies do need to be licensed as they are doing improvements to the property. Here's the link to the law:
http://www.attorneygeneral.gov/uploadedFiles/Consumers/HIC/Act_132_Home_Improvement.pdf
Page 2 covers what you're talking about:
“Home improvement.”
(1) The term includes all of the following done in connection with land or a portion of the land adjacent to a private residence or a building or a portion of the building which is used or designed to be used as a private residence for which the total cash price of all work agreed upon between the contractor and owner is more than $500:
(i) Repair, replacement, remodeling, demolition, removal, renovation, installation, alteration, conversion, modernization, improvement, rehabilitation or sandblasting
It's the state, they can make the laws work for them. Demolition and removal can be synonyms. Any kind of pruning work to trees can easily be viewed as 'alterations, conversions, or improvements.' And plantings are definitely looked at as 'installations'.
The only part I'm not sure of is if PHC needs to be covered under this, as well. I know there's a provision in this law for the Plant Pest Act, but it's not clear if that includes all PHC activities. But, once your companies licensed, you're good.