Animal community

Livestock Interpretations:
This site is suited to cattle and sheep grazing during the summer and early fall. Livestock use quaking aspen communities for forage and shade. Cattle select for understory grasses while sheep tend to select for forbs. Browsing has a direct impact on aspen. Through the early sapling stage, browsing reduces aspen growth, vigor and numbers. Heavy browsing by sheep or deer can eliminate aspen sucker regeneration. Suckers can be drastically reduced or eliminated by big game browsing on winter ranges. Aspen saplings need to attain a minimum height of 55 to 60 inches to avoid destructive browsing by livestock. Harvesting trees under a sound management program for fuelwood, posts or other products, can open up the tree canopy to allow increased production of understory species desirable for grazing and browsing.

Stocking rates vary over time depending upon season of use, climate variations, site, and previous and current management goals. A safe starting stocking rate is an estimated stocking rate that is fine tuned by the client by adaptive management through the year and from year to year.

Example: Sample Calculations using Favorable Year production amounts:

500 lbs of available forage/ac x. 25 (Harvest Efficiency) = 125 lbs forage consumed

125 lbs/790 lbs = .16 AUMs/ac or 6.32 ac/AUM

NOTE: 790 lbs/month for one Animal Unit is used as the baseline for maintenance requirements. This equates to 30 lbs/day of air-dry forage (1000 lb cow at 2.6% of body weight). See NRCS National Range and Pasture Handbook.

Forage Value Rating:
The forage value rating is not an ecological evaluation of the understory. It is a utilitarian rating of the existing understory plants for use by specific kinds of grazing animals. The amount and nature of the understory vegetation in a forestland is highly responsive to the amount and duration of shade provided by the overstory canopy. Significant changes in kinds and abundance of plants occur as the canopy changes, often regardless of grazing use. Some changes occur slowly and gradually as a result of normal changes in tree size and spacing. Other changes occur dramatically and quickly, following intensive woodland harvest, thinning, or fire.

Wildlife Interpretations:
Quaking aspen communities provide important habitat for many species of birds and mammals. This is especially true where these woodlands are the only upland hardwood tree species. Mule deer and elk use aspen woodlands for forage, thermal cover, and escape cover during severe weather and times of harassment. Commonly associated birds using aspen during breeding season include the Western tanager, common nighthawk, mourning dove, Swainson's hawk and various species of bluebird, thrush and flycatcher. Those using aspen during the wintering season include the Ruby-crowned kinglet, Townsend's solitaire, rough-legged hawk, Cooper's hawk, sharp-shinned hawk and various species of finch and waxwing. Those using aspen yearlong or as migrants include the American robin, American kestrel, mountain chickadee, scrub jay, yellow-bellied sapsucker, long-eared owl, screech owl, great-horned owl, California quail, red-tailed hawk, golden eagle, and various species of sparrow, nuthatch and woodpecker. Commonly associated mammals using the aspen community type include various species of shrew, myotis, bat, mouse and vole. Some very common species include deer mouse, Nuttall's cottontail, least chipmunk, Western gray squirrel, bushy-tailed woodrat, raccoon, long-tailed weasel and the North American porcupine. The mountain lion and bobcat use edges and sometimes the interior of the aspen community for hunting.

Wildlife and livestock utilization of quaking aspen communities varies with species composition of the understory and relative age of the quaking aspen stand. Young
stands generally provide the most browse. Quaking aspen crowns can grow out of reach of large ungulates in 6 to 8 years. Although many animals browse quaking aspen year-round, it is especially valuable during fall and winter, when protein levels are high relative to other browse species.

Hydrological functions

Well-stocked quaking aspen stand provides excellent watershed proctection. The trees, the shrub and herbaceous understories, and the
litter of quaking aspen stands provide nearly 100 percent soil cover. Soil cover and the intermixture of herbaceous and woody roots protect soil except during very intense rains.

Recreational uses

Aesthetic value is derived from the rich hues and textures of the aspen trees, particularly in the fall. The diverse flora and fauna, and the colorful wildflowers in the summer enhance the beauty of this site. The site offers rewarding opportunities to photographers and for nature study. It has high value for hunting, camping, hiking, picnicking, cross country skiing and family wood gathering. Management of the aspen woodland should include small, irregularly shaped clearcuts that blend into the natural landscape. Harvesting plans should include a mix of even-aged aspen patches in all size classes. Aspen fits well into management for dispersed recreation activities, but does not tolerate concentrated use such as found in established campgrounds. Encouraging concentrated recreation or developing campgrounds within aspen stands can lead to serious damage, including carving on trees, vandalism, destruction or removal of young suckers and trampling and disturbance of the soil.

Wood products

Quaking aspen wood is used primarily for particleboard, especially waferboard and oriented strandboard, and for pulp. Specialty
products from quaking aspen wood include excelsior, matchsticks, and tongue depressors. Quaking aspen pellets are used for fuel.

PRODUCTIVE CAPACITY
This site has a low to medium site quality for tree production. Site index ranges from 35 to 45; Site Class V (Baker, 1925).

Productivity class: 1

CMAI*: 16 to 20 cu ft/ac/yr;
1.1 to 1.4 cu m/hr/yr.
*CMAI: is the culmination of mean annual increment or highest average growth rate of the stand in the units specified.

Basal Area: Aspen 144 sq.ft./acre with average of 9” D.B.H. and average age of 60 years.(H55)

Basal Area: Aspen 160 sq.ft./acre with an average D.B.H of 9” and an average age of 89 years.(H2B)

Basal Area: Aspen 188 sq.ft/acre with an average D.B.H. of 8.6” and an average age of 60 years.(AB264)

Basal Area: Aspen 92 sq.ft./acre with an average D.B.H. of 11”and an average age of 46 years.(AB220)

Fuelwood Production: 3 to 8 cords per acre at 80 years (includes all trees greater than six inches dbh to a top diameter of five inches). There are about 203,000 gross British Thermal Units (BTUs) heat content per cubic foot of quaking aspen wood. Firewood is commonly measured by cord, or a stacked unit equivalent to 128 cubic feet. Solid wood volume in a cord varies, but assuming an average of 75 cubic feet of solid wood per cord, there are about 15.2 million BTUs of heat value in a cord of quaking aspen.
Saw timber: Growth on this site is very slow. Stands must be managed for over 140 years to reach saw timber size. Wood decay increases significantly with these long rotations. Shorter rotations can reduce decay problems but will decrease saw wood yield.

MANAGEMENT GUIDES AND INTERPRETATIONS:

1.LIMITATIONS AND CONSIDERATIONS
a. Potential for sheet and rill erosion is moderate to severe depending on slope.
b. Severe equipment limitations on slopes over 30 percent.
c. Proper spacing is the key to a well managed, multiple use and multi-product aspen woodland.
d. To begin short-rotation management, older stands with larger trees will have to be utilized.
e. Cut residual, unmerchantable, trees to stimulate maximum sucker regeneration and rapid development of a replacement stand – thin resulting sucker stands.

2. ESSENTIAL REQUIREMENTS
a. Adequately protect from high intensity wildfire.
b. Protect soils from accelerated erosion.
c. Apply proper grazing management.

3. SILVICULTURAL PRACTICES
a. Harvest Cutting: Selectively harvest surplus trees to achieve desired spacing. Harvest stands in small blocks of 1/5 to 1/2 acre with slash left in place to shelter emerging aspen suckers from browsing.
1) Clear-Cutting - Clear-cutting is appropriate when the primary management objective is sustained production of forest products, either saw timber or fiber. Cutting sub-merchantable stems along with the merchantable ones will maximize sucker production, minimize the presence of diseased or defective growing stock in the new stand, and avoid suppression of the new crop by residual overstory stems.
2) Partial Cutting - Partial cutting may be feasible in some uneven-aged stands where management objectives require vertical canopy diversity or retention of some overstory; partial cutting may result in enough sprouting to adequately regenerate stands. Individual tree or group selection cutting methods can be applied. Extreme care is necessary to avoid injury to residual stems during logging. Partial cutting is not worthwhile in deteriorated aspen clones where root system die back has reduced suckering.
3) Selective Tree Removal - Remove selected trees on suitable sites to enhance forage production and manage site reproduction.


b. Thinning - Ordinarily, only stands on saw timber sites should be thinned. Pre-commercial thinning may be uneconomical as the low productivity of this site would not justify thinning costs.
c. Protection from Disease - There are no proven forest stand treatments that successfully prevent or control disease in aspen. Maintenance of well-stocked stands, minimizing wounding of stems and control of damaging agents, and harvesting at the proper rotation age are the best management recommendations that can be made today.
d. Protection from Insects - Direct control of insects in aspen forests has not been practical. The environmental side-effects from chemical pesticide spraying usually has not been acceptable in the aspen ecosystem. Maintenance of a well-stocked stand and protection from wounding is the most practical method of coping with insects in the aspen forest.
e. Protection from Mammals - Domestic livestock, wild ungulates, porcupines, rodents and hares utilize aspen as food and can have measurable impacts on some stands. Most animal damage can be prevented by careful husbandry of domestic livestock and by population control of wild game. Because most aspen stands are grazed by cattle and/or sheep and have a significant population of wild ungulates, grazing management and game management are important to aspen communities.
f. Fire Management - Fire is a natural feature of the aspen ecosystem. Fire is considered responsible for the abundance of aspen in the west as well as the even-aged structure of many stands. Without human intervention, fire appears to be necessary for the continued well-being of aspen on sites where natural degeneration of the clone occurs, or where insects or pests are especially harmful to the stand. Fires in aspen generally are infrequent, spread slowly, are of low intensity, and are easy to control. Although aspen forests do not burn readily, aspen trees are extremely sensitive to fire. Even very light fires will kill aspen because the bark is thin and green, and lacks protective corky layers.

Other products

Historically quaking aspen has been used for mine props, posts, bridge planking, flooring, furniture and fuelwood. This tree has a considerable potential for increased utilization. It makes excellent pulp, excelsior, door corestock, paper, particleboard, matchsticks, structural flakeboard, lumber products and boxwood. An undesirable characteristic of the quaking aspen stand is their heavy drain on available water in the soil.

Other information

Aspen propagates almost entirely by vegetative means throughout the Great Basin. Regeneration by seed is very rare, although aspen in this area produce large quantities of viable seed. Aspen seeds require a continually moist seedbed and the dry spring and summers of the Great Basin are not conducive to seedling survival.
An undesirable characteristic of quaking aspen is their heavy drain on available water in the soil.

Table 7. Representative site productivity

Type locality

Other references

Airola, D. A. 1980. Northeast Interior Zone: Vol. III - Birds & Vol. IV - Mammals. U.S. Gov. Printing Off.: 1980-690-082/26.

Alexander R.R. 1987. Ecology, Silviculture, and Management of the Engelmann Spruce-Subalpine Fir Type in the Central and Southern Rocky Mtns. Ag Hndbk No. 659. Rky Mtn For & Rng Exp Sta, USDA-FS.

Baker, F. S. 1925. Aspen in the Central Rocky Mountain Region. USDA Technical Bulletin 1291.

Cryer, D.H. and Murray, J.E. 1988. Aspen Regeneration and Soils. USDA, Bulletin 1291, 47 p. Washington D.C.

DeByle, N. V., and R.P. Winokur, editors. 1985. Aspen: Ecology and Management in the Western United States. General Technical Report RM-119, Rocky Mtn For & Rng Exp Sta, FS, USDA.

DeByle, N.V., P.J. Urness, and D.L. Blank. 1989. Forage Quality in Burned and Un-burned Aspen Communities. Research Paper INT-404. Inter. Res. Sta., FS, USDA.

Edminster, C., et al. 1982. Volume Tables and Point-Sampling Factors for Aspen in Colorado. Res Paper RM-232, Rocky Mtn For & Rng Exp Sta. USDA-FS.

Eyre, F.H. (editor). 1980. Forest Cover Types of the United States and Canada. Society of American Foresters, Washington.

Fire Effects Information System[Online], http://www.fs.fed.us/database/feis

Plants Database [Online], http://www.plants.usda.gov

Contributors

ALC/GKB

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