[defrost]

The usual kind.

You know how light reaches the forrest floor? So does LIDAR.

If you get raw data from a LIDAR device (as opposed to the usual commercial internally "processed and smoothed" relatively low frequency data stream) you get a high frequency noisy cloud.

The HF cloud includes returns that bounced from the upper canopy and returns that bounced from the forrest floor.

You write your filters to pick the features (tree tops, tree foor, canopy density estimates, etc) you're interested in.

It's also possible to map recent snowfall depths with LIDAR | microwave RADAR tweaks.