Checking for amount of saplings being placed

Hi fellow modders 

I'm trying to write a few little special hidden 'rewards' for a support mod to a streamer community modpack.

One of these rewards is a 'farmer' one where I am trying to check how many saplings a player has placed.

I have the basic concept down :-

I'm checking to see if a block has been placed by a player

I have a counter for the amount being placed 

I want to check for all saplings tagged by forge as such rather than just one item eg (oak sapling)

 I cant seem to figure out how to test if a player has placed tagged items rather than an individual block

Any ideas?

Many thanks

Goth