.
Here are some online resources and links to help you understand the didgeridoo better.
General links:
A virtual museum of sound and a sonic exhibition of didgeridoos on SoundCloud
Yidaki: Didjeridu and the Sound of Australia
Didgeridoo Australia: Aboriginal Cultural Experiences
Joshua Bell > In Between Songs
The Melbourne Didgeridoo and Cultural Festival
The Australian didjeridu: A Late Musical Intrusion
Savanna ecology, fire frequency, trees and termites in Australia:
http://www.sciencedirect.com/science/article/pii/S0378112708003691
http://onlinelibrary.wiley.com/doi/10.1111/aec.12052/abstract
http://www.environment.nsw.gov.au/determinations/lossofhollowtreesktp.htm
Permits, licences:
http://www.dpaw.wa.gov.au/plants-and-animals/licences-and-permits/135-flora-licences