Certain chunks won't generate trees properly

I just generated a new world in Creative mode, and I noticed that certain chunks did not generate trees that had "sprouted" other chunks properly. These trees were either cut in half or had parts of their leaves missing. I noticed this with all tree types except for acacia trees.
When it happened to the spruce trees in the Extreme Hills biome, I also noticed that it did not generate the the snow that is supposed to be above a certain height on mountains.