According to AZDA.gov
Cactus wood, the skeletal remains of some cacti, is not protected under the Arizona native plant law. However, it is suggested that written permission be obtained from the landowner before entering any private property, especially to remove resources.
Skeletal remains of the Saguaro and Cholla cacti being taken from private, State, and Public lands in Arizona may have an adverse impact on the fragile desert environment. The removal of cactus wood is an increasing practice that may have a cumulative negative effect on wildlife habitats and populations, as well as injury to plant seedlings.
The organic content of the desert soil is very low, and decomposition of cactus remains plays a vital role in maintaining soil fertility. Dead and decaying cactus also provide food and habitat for a wide variety of wildlife and perch sites for raptors. Written authorization from the State Land Department must first be obtained before entering State Trust lands. Questions regarding natural resources on State land, please call the State Land Department at (602) 542-2119. Written authorization for the commercial removal of natural resources from Public Land (Bureau of Land Management, National Forest Service) must first be obtained from the land managing agency. For more information regarding Public Land, please call the Bureau of Land Management at (602) 650-0200 or the National Forest Service at (505) 842-3292 in Albuquerque, New Mexico. Remember, open land in Arizona belongs to, or is controlled by someone. Be sure to have written permission in hand before entering any land to remove natural resources.
Again, cactus skeletons (or any dead plant or plant parts) are not protected under the Arizona native plant law. However, we encourage that at least verbal permission be obtained from the landowner before entering private property.
For additional information, please call Scott Schade , Office of Special Investigations at (520) 628-6317, or e-mail at [email protected]
Taken from a PDF on their site