This is a bonus cache for the Adventure Lab, University of Washington Tree Tour. Complete the tour, then examine the five journal entries. They mention 8 other species of trees beyond the 5 targeted in the Tour (Sycamore, Yoshino Cherry, Cork Oak, Shore Pine, Giant Sequoia). Find the numbers of the 8 other species in the Brockman Memorial Tree Tour. Multiply the 8 numbers together, to get a 12-digit number: ABCDEFGHIJKL
Let M = 10-D, N = G+L, P=C+3, Q=8-K, R=E+1, S = B+F, T=A+I.
Find the cache at N 47 3M.NJP W 122 1Q.RST.
You can validate your puzzle solution with certitude.
Notes: The tree tour is likely to change; you can find a list of species as of the date the cache was placed in the Image Gallery.
There is a hide hint in Certitude.
Congratulations to latetrap on the FTF!