Unformatted text preview:

SUBALPINE FOREST GEOGRAPHY Species Tn Darninant taxa of the subalpine zone (above c. 9300 ft.) A. Engelmann spruce (Picea engelmannii) Appearance: Tall, slender, conical crown. Dark green, sharp ndles are square in cross-section and appear singly on branches. Bark is reddisWgray with scales. Twigs have small nibs from former neeidlcr. (Spruce: sharp, square, single, scales.) Habitat: Mesic (moderately moist) and wet sites. Reproduction: Mderate seed pduccr; highIy variable amounts of soed per year, but normally at least some sd each year. Layering (branches pinned to ground by snow can rmt and form new trees). Understory tolerance: Semi-shade tolerant. Under low light Ievels it has a lower photosynthetic rate than subalpine fit. Seedling establishment: Bes on bare mineral soil and moist logs Under low light, seedlings require high moisture. Under high Irght tliey can esbblish on dncr sites. Tmpedimcnts to establishment ~nclude: leaf litter, snow mold, and clipping by birds and small mammals. bngevl ty. In the Front Range It often attam ages > 500 yrs (and rarely over 800 yrs). Its rnortnlity rate may be lowcr than that of subalp!ne fir. Uarnaglng 3zcnts Spruce beer Ze (Dcndrocronrl.~ n!fipemis) attack large I~ve and dcad trees Not \\rindfirm. Easily killed by fire. 1,ess st~sccptible to fi1nga1 pathogens than subalpine fir. - , - '5 / -B. Subalpine fir (Ables lusiocarpa) Appearance: Tall wth very slender Gonical crown. Grcen noedIes appearing singly on branches. Needla are flat in cross-section with rounded tips (friendly, not sharp). Bark is generally light gray and smooth. (Fir: flat and friendly.) Habitat: Similar to that of spruce, but it also tolerates dries sites. Reproduction: Generally produrn lea seed than spruce and in sane ycars seed production may be nil. Layers in the kmmhdz zone and also in subalpine forests. Longevity: Generally, it dms not attain as great an age as does spruce. Trees older ahan 300 years arc scarce, although occasionally trees over 400 years occur. Understory tolerance: Shndc tolerant. Under low light levels. greater photosynthetic rate than spmw. However, both species survive under similarly low light levels. Seedling establishment: Much more abundant on litter than 1s spmce, presumably due to its more rapid root elongation. Fewer seedlings on logs than for spruce. Also establishes on bare mineral soil. Darnaging agents: Not fire resistant. Ips beetles cause a small amount of mortality. Highly susceptible to filngat patfaogcns once trees reach c. 150 yrs, causing internal rot. Not windfirm. . . . -- LC. Lodgepole pine (Pinrrs conforfa var. lobfo/ia) Appearance: Tall, generally, very straight, pole-shaped trunk. If grom alone, the tree is less straight and mote branchy. As density increases, the trees become very narrow and straight. At extrcme densixies (dogha~r mnds), the trees hemme stunted and maintain small diameters. Ndles are dark green, grouped together in two's and held together by a papev sheath at their base (fascicIe). Nlsedles are D-shaped in cross-section. (Lodgepole: two syllables, two needles.) Habitat: Overlops with spruce and fir but more abundant in tht lower subalpine zone and on drier sites. Reprduct ion: Prolific and prwious (earlyrnatunty) cone prduction. Serotinws cones (dosdd and cemented with resin; they open upon heating). Longevity: Generally less long-lived hart spruce, but can attain ages > 400 years. Understory tolerance: Not shade tolerant. Wtll not survive in the understory of a spruce-fir forest but can grow through the canopy of an open aspen stand. Secdling establishment: Best on hare mincral soil. Damaging agents; Mountain pine k11e (Dendroctonws ponderosae) and other bark beetles. May mist fire slightly her than spnlce or f r, but is easily killed by crown fires. Usually abundant establishment after fire. Not windfi mD. Limber pine (Pirrtrs~exilis) Appcarance: Broad, branchy cro~m. Individuals often grotlped in clumps. Needles in groups of five clumped at the ends of brancblets. Branchlets are very flexible (limber). Young bark is light gray and srnmth, with older bark deveIoping darker hrrows and ridges. eimbcr pinc: five and flexible.) Habitat: Generally at dry, rocky sites; exposed to high winds. Somc also at lower elevation. Reproduction: Sds are dispcrscd and cached by a bird, the Clark's Nutcracker (Nucuraga coiumbiona). Longevity: Oflen attains ages > 1000 ycars on extreme sites, otherwise suded by spnicelfir within 200-400 years. Understory tolerance Extremely shade h2sleranb. Seedling establishment: Dare mineral soil; especially rocky areas. Damaging agents: More fire resisrant than the other subalpine trees. Windfirm (long tap root). Yorcup~ne damage.E. Aspen (Populus rremuloides) Appearance: Tall with roundish crown percM at the top of the Cree. White ro parchment colored bark. Leaves are orbicular (round) with a flmi ble petioIe (attaches them to the branch). Leaves are deciduous (lost in autumn, regrown in spring) and tremble in the breeze, Habitat: Wide range: both dry ridges and moist riparian areas. Reproduction: Establishment from sd is rare. Primarily reproduces vegetatively (rmt suckers). Longevity: Vwy short-lived; bees older than 200 years are rare. Most stands > 120 years old appr senescent. Understory tolerance: Shade intolerant. Damaging agents: Fire kills aenal portion of tree, but root stock can survive at least lower intensity bums. Susceptible to a canker disease which can kill entire clones (ie. don't cam your initial in them!). Hro\vsing by large mammals GUI severely damage trees.Srt ccessionnl ,%quence The Pinus jlrexilis - Picea, A bies (limber pine, sprucelfir) forest subtype (Peet I98 1) is comprised of three dominant canopy tree species, limber pine (Pimsflexilis James), EngeImann spruce (Pacea engelmnnnii Parry ex Engelrn.) and subalpine fir (Abies Imiocarpa mook.] Nutt.). Trembling aspen (Poprilus tremuloides Michx.) and Iodgepole pine (Pinus conlorfa Doug]. w. lufvolia Engelrn.) co-occur, though less frequently. These forests range in elevation from approximately 3 150 rn (10,300 ft) to 3450 rn (1 1,300 ft) in the Colorado subalpine zone (Peet 198 1)- These subalpine communities are characterized by stand devastating fires occurring at approximately 200- to 400-year intervals (Romme and Gght 1981, Mast and Veblen 1994). Following fire, an avian fmgivore, the Clark's nutcracker (Nucrfioga columbium Wilson), caches limber pine seed in the burned sites. Seed is obtained


View Full Document

CU-Boulder GEOG 1001 - SUBALPINE FOREST GEOGRAPHY

Download SUBALPINE FOREST GEOGRAPHY
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view SUBALPINE FOREST GEOGRAPHY and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view SUBALPINE FOREST GEOGRAPHY 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?