I guess the type of feedstock matters for the pore structure of the final product. I would use any wood because the wood has plenty of pores for soil life to use and greatly increases the surface area. This larger surface area allows more contamination to be adsorbed (not absorbed). There are other benefits as well. This is a deep rabbit hole to go down let me know if you want suggestions for podcasts or videos on the subject. Here is a picture under a microscope