Hi,
from what I have can tell in my version of Zorin 9 (Ubuntu 14.04.0); there won't be an update for kernel 3.16 series, the highest I have right now is 3.13.
Do you really have such modern hardware that you need the 3.16 kernel?.
You can add the Linux kernel PPA but if I were you, I would stick with what you have.
As of Ubuntu 14.04.02 (I think), 3.16 is included by default, I don't know whether the Ubuntu Mate devs have plans to do another update of Ubuntu Mate, the last available version is 14.04.1:
https://ubuntu-mate.org/trusty/
Maybe one of the mods can shed some light on that matter for you!. 
I am using UM 15.04 Beta 1 and it runs fine if you feel like updating because you want/need the 3.16 kernel!.
You can keep all your data intact if you follow this advice:
REMEMBER THAT UBUNTU MATE 15.04 IS STILL IN BETA!!!!!!!.
(I don't have any problems with it myself and I have it running on 2 PC's but I just want to make you aware that it is Beta!.)