Do plants roots attract to this type of material, leading to the breakdown of such products?
Asphaltic and asphalt coal tar based systems have shown good resistance to root growth/attack over the years. There is a recent test procedure used to qualify roof barriers for greens roof systems, ANSI/GRHC/SPRI VR-1 2011 Procedure for Investigating Resistance to Root Penetration on Vegetative Roofs.