First five or six pictures look like eucalyptus to me. The other ones might be Acacias but I have no clue, yu should look up the south african acacias in this thread:
https://www.dmt-nexus.me...spx?g=posts&t=23472
and then you should try to look up all the ones listed for south africa, see if you find close candidates and then suggest/ask for confirmation after youve done your part of the research. Also, for identification of plants, one needs close up of plants, and flowering/seedpods are very important too, so if you're in the wrong time of the year sometimes it will be impssible to get full identification.
The later pics with the cane-like plants seem like they might be Arundo donax, This plant is a cocktail of alkaloids and in some parts of the world were not found with DMT. You would be doing a kind of russian roullette there, I suggest looking into TLC if you want to work safely. Then the last pics might be phragmites australis or some phalaris, its really hard to say without flowers and close ups and so on.
Also, "mulcher" sounds like you'll be extracting big quantities of bark, which can kill a tree. Please read that acacia thread for 'sustainable harvesting'.
Check this wiki with all the DMT plants too:
https://wiki.dmt-nexus.m...T#Plants_containing_DMT
You should tell us which plants you think they are, do your own first screening so it helps out with the research.