The reasons are humdrum enough: habitat degradation and destruction, usually through agriculture, forest destruction, draining.

The more forest destruction, the more human-elephant conflict.

This massive invasion resulted to a high rate of forest destruction and timber poaching.

As a source of soft wood, bamboo can complement/substitute for timber wood, and help reduce forest destruction.

For example, changed weather patterns may create favorable conditions for pine beetles, leading to large beetle outbreaks and forest destruction.