How do vertical climate zones affect vegetation on a mountain?

Answer 1

For example, Mount Everest is a very cold place so less vegetation is likely to grow there. Especially Mount Everest is located at a very high elevation so that is another reason.

'Climate Zones' is another term that is used to describe the entire Biosphere of an environment. This translates, in the specific cases of [vertical or horizontal] climate zones, into how varying Climates affect the related Ecosystems.

As concerns elevation, there is a well defined rate-of-cooling-of-the-Air as elevation increases - something like minus 6 degrees C per 1 kilometer of Rise. In Meteorology this is known as "The Adiabatic Lapse Rate".

{Proof: Airliners travel at an altitude of 9 km: 9*(-6)= -54 C, which is the temperature outside of the in-transit airliner.}