How to make a tree and leaves?

That's quite a bit complicated and I don't know if it's really possible but let's see...

1. You have to create your .schematic of your tree if you don't want your tree to be a common vanilla one, so make your log block (done) and leaves block.
   Export your mod and put it in minecraft, then open it and create with your custom log and leaves a tree as you like.
   Once you've done, close minecraft and open that world in MCEdit (I recommend MCEdit 2), select your tree and export the .schematic.
2. Now Create your sapling block (create sapling texture and set the block model to cross X). Create new event on block rightclicked, set as a condition itemInPlayersHand and put bonemeal, then make a stack event. In that, add new event, set as a condition randomPossibility[x%] (with x = whatever you want your probability to spawn the tree with bonemeal is) and select place schematic. Choose your tree .schematic you made before and add the event.
   Then, always in that stack event, add another one and select consume item in inventory and select that you consume 1 bonemeal at click. Then press on Add event.
3. Now you have to edit your leaves block. Remember to set its drop amount to 0 and make an event so when block destroyed by player --> spawn gem and add condition randomPossibility[x%] (x = whatever number you want) and choose your sapling block to be "spawned as a gem". 
   To let your leaves drop your sapling blocks when you've destroyed the log, it's a "bit" complicated.
4. At last you only need to create your Biome and set your tree .schematic ​as trees.

Maybe for bonemeal you could use global events but I prefer this since you cannot edit global events code

and if you do something like:when in specified spaces the block is not your tree's log the leaves start to randomly destroy and drop randomly their sapling or something like this?

i think it can be made because the tree is a schematic and can't be different so you will know were exactly the block had to be

sorry for bad english but it isn't my main language

how do you that canshow like pics or video  want i dont get that 

Make your tree as a structure 

no i mean how 

How to do a random chance operation?

When you create your procedure, you can select a template, just select "Do with 70% chance" and then, you can change the number to change how random is your thing.

Cool, also how would we make it decay? I tried making a procedure to check a 3x3x3 area (I'll increase so my tree doesn't fall apart), but whenever the leaf breaks (which it breaks even if there's a log next to it), it becomes a ghost block.

Nevermind, I'm just following a tutorial.

dude just use the leaf block base and tag logs as logs

it is so much easier

Where is the place schematic block?

Then i dont need do it via template? Can i create the tree too on this way?