system
Given the following post, respond as if you're commenting on Reddit:
human
Why do coniferous trees only seem to proliferate in mountainous or northern environments?

I live in the Eastern United States. The only time I ever see conifers or "pine trees" is at Christmas or in the occasional wild grove or landscaping area. Yet out west in the Rockies, British Columbia, and everywhere in southern Alaska, conifer forests dominate, even at low elevations. Why is this? 

EDIT: Thanks for your responses! Although, let me be clear, I am fully aware that coniferous forests exist outside of the regions I provided; my Dad's family grew up near the Pine Barrens of New Jersey. All I was saying was that in Alpine environments and Northern regions, coniferous trees dominate.
gpt
Conifers can grow just fine in temperate climates, but they'll usually get outcompeted by those faster-growing broad leafed deciduous tree like oak, maple, etc. But they have adaptations which allow them to do much better in colder climates than their broad-leafed competitors: their sap contains antifreeze like compounds; their small, wax-coated needles are less vulnerable to damage from cold weather, and can retain moisture well when liquid water is in short supply; since they don't have to drop their leaves, they can "wake up" from their winter slumber and start photosynthesizing before deciduous trees even start to bud.