They specify a vacant farmstead. In that part of the country, the nearest "neighbours" can be 10 or more miles apart. Keep in mind that there are large parts of Montana and North Dakota that average less than two people per square mile of land. That's a lot of land with very few people.
It's not so hard for me to believe that there are vacant farmsteads that have been forgotten. I mean, "vacant" could apply to a farmhouse that was vacated a year ago or more than a century ago. At least they specify a treeline! "Matted grass" covers most of the area at this time of year and is not at all helpful as a location clue.
The problem is that just about every vacant farmstead has at least one treeline. "Mature or rotted" trees suggests that the place may have been vacant for many years, and therefore more likely to be forgotten.
Absolutely... Especially in that part of the country. I hate to say it, but finding a buried body up there would be next to impossible, unless you know exactly where it is. All of the land up there is owned by someone, obviously (outside of the federal government), but often times it's pasture land... You wouldn't notice something out of the ordinary... and it's often rented out... A lot of it is pasture land (for cattle, livestock), and for crops (although not so much in that part of Montana/North Dakota... the soil isn't as fertile). Landowners up there definitely need to be on the lookout... But, I wonder where the "treeline" came from... directly from the suspects? That being said, the "treeline" could be anywhere.