I've used search bar and cannot find this.
When taking away the trunk of a tree and you leave it (with leaves exposed directly to sunlight) the leaves disappear as you would expect. However, if you take away the trunk of a tree under another tree (ie a low lying one in the jungle) and there are leaves covering the light over the lower leaves, the leaves underneath do not disappear, no matter how many nearby trunks you take away. Any questions just ask.