What will be the best approaches to get information about forest tenure system, issues related to forest tenure of an area to get scientific base result .
You may be able to get people to help if you emphasize forests as a matter of patriotic pride without politicizing it. It is unclear what these issues are. However for some issues you can ask school teachers to help you gather information. Or maybe public health workers for information on what they are seeing. Perhaps you can get satellite photos from sources found somewhere on the internet. If you can find a computer with a good Nvidia video card it is possible to squeeze additional information out of satellite photos using pytorch. However, such cards are hard to get now. If you do not have one you might seek a grant for a couple of thousand US to buy one (maybe even ask Nvidia or a gamming machine company to help with a good cause).
Best wishes, baseline information regarding forests is a great contribution to us all.
Are you considering a survey of this district?? In which case, perhaps you would consider cluster sampling, where each cluster is a small grid cell, selected at random, and each grid cell is censused.
Unsettled districts usually have indigenous residents and more recently settled residents. Discussions on location with these people can produce a wealth of local knowledge to encourage co-operation and avoid tenure issues. there may also be unofficial small scale forest tenure systems in place that could be accommodated.