Well, the Forest Pack 4.3.7 it's not officially supported under 3ds Max 2016 (and therefore not recommended).
As general rule is not a good idea to install different versions of the plug-in, because the libraries, maps and materials are stored in a same folder, but in your case it could be an option to have both of those FP versions installed.
Under the Advanced Installation
mode it's possible to uncheck the 2014 version (or any other) from the Select components to install
list. This way installation for unselected automatically found 3ds Max version will be skipped and into your 3ds Max 2016 path will be installed correct dynamic library version. (attaching screenshots)
Anyway, we've released Forest Pack Pro 4.4.1
(In this release should be fixed all rendering problems with Mental Ray and Max 2016). I would highly suggest you to proceed installation of this actual version.
Hope that helps.