You may have seen these, but just in case you haven’t
Temporary effect of mtb and hiker
http://got.net/~landauer/mtb/Guelph_MTB_study.pdf
https://www.uvm.edu/~snrvtdc/trails/Com … mpacts.pdf
see pages 555 -556
https://www.uvm.edu/~snrvtdc/trails/Com … mpacts.pdf
And here is one from the other side, high on emotion but short on facts
and science
http://www.culturechange.org/mountain_b … mpacts.htm
Google page results
https://www.google.com/search?q=mountai … gws_rd=ssl
Good Luck!