Re: Which tree grows at a higher elevation, a fir tree or a pine tree?

Firs and pines are both members of the plant family called the 
Pinaceae (pin-A-sea-E). The Pinaceae are part of a larger group of 
vascular plants commonly called conifers. The various genera (the 
level of classification just above species) in the Family Pinaceae are:

Genus Abies -- fir (12)
Genus Cedrus -- cedar (1)
Genus Larix -- larch (5)
Genus Picea -- spruce (9)
Genus Pinus -- pine (50)
Genus Pseudotsuga -- Douglas-fir (2)
Genus Tsuga -- hemlock (5)

The numbers in parentheses are the approximate numbers of 
species in each genus that grow without cultivation in North America.

High altitude habitats are generally dominated by firs, spruces, and 
pines. There is an altitude, called the tree line, above which no trees 
will grow, although some, typically tree-like groups -- genera -- such 
as willow trees (Genus Salix, Family Salicaceae), have 
representatives -- species -- that grow as dwarfs or shrubs at this 
altitude. The exact elevation of the tree line varies geographically and 
locally, according to environmental factors, such as temperature and 
moisture. In some parts of the world, trees do not grow above 6000 ft. 
In others, trees will grow even above 10,000 ft. The elevation at which 
trees will grow also depends on the species, and these vary 
geographically as well.

At or near the tree line, trees become stunted by the harsh 
environment and misshapen by the wind. This type of vegetation is 
called krummholz (from German for ‘bent wood’). The tree most often 
listed as characteristic in krummholz formations is Engelmann 
spruce (Picea engelmannii).

Apparently, no one has made a big deal of high-altitude tree records 
by species. I conducted an extensive search for such records on-line 
and found nothing. I even searched the Guinness World Record site
 http://www.guinnessworldrecords.com/

to no avail.

In descriptions of high altitude communities that I have found, pines 
and “firs” (loosely construed to include other, non-pine conifers, 
including junipers (Juniperus) in the cypress family Family 
Cupressaceae) seem to get roughly equal time. For example, in a 
description of a transect of the Sierra Nevada Mountains at the Sierra 
College Natural History Museum in California,
 http://www.sierra.cc.ca.us/museum/forest2a.htm

3 pines (Western white pine, Pinus monticola; lodgepole pine, Pinus 
contorta; and whitebark pine, Pinus albicaulis) are mentioned as 
growing at the 9000 ft. level (which seems to be the highest point in 
the transect). The only non-pine conifer mentioned is mountain 
hemlock, Tsuga mertensiana. Pines win that round.

The Colorado State University Cooperative Extension Service, in a 
fact sheet for “Trees for Mountain Communities,”
 http://www.ext.colostate.edu/pubs/garden/07408.html

lists 3 pines (bristlecone pine, Pinus aristata; lodgepole pine, Pinus 
contorta variety latifolia; and limber pine, Pinus flexilis), 2 spruces 
(Engelmann spruce, Picea engelmanni; and Colorado spruce, Picea 
pungens), a fir (subalpine fir, Abies lasiocarpa), and a juniper (Rocky 
Mountain juniper, Juniperus scopulorum) as hardy at least up to 
10,500 ft. Given that they equivocate about the viability of several of 
the non-pines, pines win that round also.

My personal (non-scientific) experience East of the Mississippi tells 
me that, most often, the non-pines predominate at the highest 
altitudes But that does not preclude the possibility that a few pine 
individuals are mixed in, perhaps at the highest reaches.

In short, I don’t think you will find an answer to your question because 
you may well be alone in your interest. Also, because both pines and 
non-pine conifers grow pretty much equally well at very high altitudes, 
the task of determining the absolute highest in the world would be 
truly daunting.

I  hope that this answer has given you some food for thought and that 
its lack of finality is not too frustrating.