I am working on the Leave No Trace Award with my Cub Scout Den and received the following information from The Leave No Trace Center for Out Door Ethics.
“The Leave No Trace Center for Outdoor Ethics do not have a recommendation either for or against tents and/or hammocks. We advocate for enjoying the outdoors responsibly.
The biggest different is that when properly used, hammocks can eliminate much of the impact generally associated with tent camping. When tent camping, you are impacting a larger area just by the sheer nature of a tent’s size and the additional impact of sleeping pads, sleeping bags and the campers inside.
As long as ‘tree saver straps’ (2-4” wide straps that go around the tree to minimize any girdling effects) are used, there is very little impact associated with hammock camping. Besides getting in and out of the hammock, the ground beneath is almost untouched. Additionally, a hammock allows for greater flexibility when choosing a campsite. When looking for a tent site, level ground is generally preferred. However, with a hammock, one can essentially camp wherever there are trees. This could be on a steep slope, over boulders, snow or other surface the might not be suitable for tent camping.
There is a book that you may find useful, and one that we helped review and provide Leave No Trace information for: Hammock Camping – A Guide to the New Comfort, Convenience and Freedom In the Great Outdoors, Written by Wade Edward Speer”