Trilateration (often mistakenly called triangulation) is the process of determining a location given distances to other known locations. Since all the caches are in trees, I have named the series 'treelateration'. To find this bonus cache, you'll have to use the clues contained in the traditional caches of the series.
These are the caches you'll need to find in order to get the coordinates for this one:
Each of these caches contains a number, which is the distance in meters from that cache to one of the bonus caches. Some of the caches contain two numbers; for these, each number is a distance to a different bonus cache. Once you think you have the solution, check your answer on Geochecker.
Once you've found all three bonus caches, you should have all you need to find the super bonus cache.