Vascular Plants of the San Francisco Peaks Area
	Key and Descriptions of Life Zones (LZ)
1	High elevations (≥ 11,500 ft or 3,500 m) without trees > 3 ft (or 1 m) tall ……………………………………………………..					LZ 8, Alpine tundra
1	Lower elevations, or trees > 3 ft (1 m) tall are present… 2
2	Trees < about 20 feet (6 m) tall… 3
2	Trees > 20 feet (6 m) tall…4
3	Major trees are bristlecone and limber pines ……				………………………………………………………………………	LZ 7, Hudsonian woodland
3	Major trees are pinyon pine or junipers……………				………………………………………………………………………	LZ 5, U. Sonoran woodland
4	Tree regeneration includes Engelman spruce or
		corkbark fira …………………………….			………………………………………………………………………	LZ 7, Spruce-Fir forest
4	No regeneration by above treesb ... 5
5	Tree regeneration includes white fir, southwestern white pine, or Douglas-fira (D-fir) ……………………………………….					LZ 6, Mixed conifer forest
5	Tree regeneration is mostly ponderosa pine (some pinyon, southwestern white pine,
	or Douglas-fir may be present ………………………………………………………………………..					LZ 5, Ponderosa pine forest
	aThe indicated trees must be present as seedlings or saplings
	bThe indicated trees are absent or minor compared to other tree regeneration
8	Alpine tundra is the most restricted environment in Arizona, and all of it occurs in the high Peaks
	(elevations above 11,500 ft). The tundra consists mostly of boulder fields, loose, gravelly talus, and
	rock outcrops whose fragmental soils support few plants.  Well-developed soils are uncommon,
	but they feature a more diverse flora. The rarest of all tundra environments are snowfield wetlands.
	Tundra vegetation lacks taller statured trees but includes "trees" of shrubby or wind-deformed
	appearance (krummholz).
7	Spruce-Fir (S-F) forests are recognized by dominance or good regeneration from either or
	both of Engelman spruce (Picea engelmannii) and corkbark fir (Abies arizonica).  At low
	elevations S-F forests can be confused when conifers of other life zones are also present as
	regeneration or overstory trees.  However Engelman spruce and corkbark fir are still common
	as seedling or sapling trees.  S-F forests can be either closed-canopied or open forests.
	Mostly at higher relevations, open forests have scattered trees or small copses within a more
	continuous herbaceous ground flora.  These open forests are often described as "park-like".
	Included within the S-F life zone are other important plant communities. Aspen deciduous
	forests are common at lower elevations.  Aspen (Populus tremuloides) usually forms a closed-
	canopied forest, punctuated by overstory or regenerating conifers.  Stands develop after hot
	forest fires kill most pre-existing conifers.   Stems (known as ramets) spread by suckering from
	underground structures, and thus stands begin as clones (genetically identical stems) in patchy
	arrangement with other clones in the burned sites.  Eventually conifers reseed themselves.  As
	they grow and overtop the clones, the ramets die, but their underground structures remain alive
	within the now-coniferous forest, awaiting the next hot fire.
	Parks are herbaceous openings lacking trees for the most part.  The Inner Basin has extensive
	parks.  Other examples include Aubineau Park on the north slope of Humphrey Peak and fescue
	meadows (dominated by Festuca arizonica) along upper reaches of the Weatherford trail.
	High-elevation woodlands in the S-F life zone consist of trees less than 20 ft (8 m) tall at maturity.
	The principal trees are bristlecone and limber pines (Pinus aristata and P. flexilis).  Woodland
	sites are typically windy and dry relative to sites of adjacent taller forests.
	High-elevation wetlands contain plants depending on more site moisture than supplied by onsite
	precipitation alone.  Typical sites receive growing season meltwater from snowfields above or
	water from adjoining springs or seeps.  We use the term drylands for lands receiving soil water
	in the form of onsite precipitation only.
6	Mixed conifer (MC) forests are identified by dominance or good regeneration from white fir (Abies
	concolor), Douglas-fir (Pseudotsuga menziesii), or southwestern white pine (Pinus strobiformis).
	Seedlings or saplings of Englemann spruce and/or corkbark fir are absent or minor (i.e. restricted to
	favorable microsites but otherwise absent or rare).  At lower elevations or warmer sites MC forests
	can be confused with ponderosa pine (Pinus ponderosa) forests when this pine is common in the
	overstory.  However, ponderosa pine is not regenerating well or is merely accidental in special sites,
	whereas white fir, Douglas-fir, or southwestern white pine remain common as understory seedlings or
	saplings.  MC forests are usually close-canopied, but are also found as park-like forests.
	Aspen deciduous forests occur throughout the MC lifezone.  Their ecology is the same as described
	for the S-F life zone.  Parks and wetlands are also found, but woodlands are rare because of lack
	of requisite exposed, dry sites at these mid-elevations.  Wetlands contain many plants that would not
	otherwise occur in the San Francisco Peaks area.  Important (for their plant diversity) wetlands and
	parks in the MC life zone include the upper reaches of Hart Prairie, Lockett Meadow, Bismarck and
	Walker Lakes, and the stock tanks at Schultz Pass.
5	Ponderosa pine forests are either close-canopied or open and park-like.  This forest is identified
	by absence or very minor occurrence of white fir and Douglas-fir either as regeneration or overstory
	trees.  Ponderosa pine has numerous seedlings and saplings and/or pole-sized trees ("blackjacks")
	in closed canopy with or without larger and older yellow-barked trees ("yellow bellies" or "yellow pine")
	in park-like structure or mixed with blackjacks in dense stands.  At higher elevations or cool, wet
	microsites Southwestern white pine may also occur with ponderosa pine.  Such sites might also
	feature aspen deciduous forest, which is otherwise uncommon in this life zone.
	At hot, droughty sites under 7,500 ft elevation at Dry Lake Hills and Mt Elden are woodlands of
	pinyon pine (Pinus edulis) and junipers (mainly Juniperus deppeana, J. monosperma).  Common
	associated shrubs are mountain mahogany (Cercocarpus montanus), gambel oak (Quercus
	gambelii), and sumac (Rhus trilobata).  Parks, both small and large in size, also occur in this life
	zone, and within these parks are wetland microsites such as stocktanks and small springs.
	Special environments at Dry Lake Hills and Mt Elden are the dacite rock outcrops, cracks, and
	ledges that support a diverse fern flora and other plants found only at these microsites.  There are
	also sites with cindery and calcareous soils supporting a distinctive flora.
					revised	February 4, 2005