The BC provincial government and Royal Dutch Shell (and others before) are trying to develop coal-bed natural gas in the Bulkley Valley in Northern BC but are meeting fierce resistance with First Nation and local representatives who have roadblocks etc planned. Is it possible that this is one reason there is a difference between reserves and resources? Increasingly the natural gas reserves are cohabitating with ecosystem services??

I doubt that this sort of thing accounts for much of the difference, in Canada at any rate. "Reserves" are discovered and available gas (not too far from pipelines). "Discovered resources" have been discovered but are not (yet) available for whatever reason, including angry residents. For most of Canada's "Discovered Resources", I think the problems are distance and technical challenges. "Undiscovered Resources" are too much of a guessing game for the attitudes of local residence to make a significant difference, even if they are considered when compiling the numbers.

The situation in the US may well be somewhat different.