Index of Species Information

SPECIES:  Corylus americana


SPECIES: Corylus americana
AUTHORSHIP AND CITATION : Coladonato, Milo. 1993. Corylus americana. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [].
ABBREVIATION : CORAME SYNONYMS : NO-ENTRY SCS PLANT CODE : COAM COMMON NAMES : American hazelnut Americam hazel American filbert TAXONOMY : The currently accepted scientific name for American hazelnut is Corylus americana Walt. [17,31]. Two subspecific taxa based on morphological differences are found in southwestern Missouri and southeastern Kansas: C. a. var. indehiscens Palm. & Steyerm. and C. a. forma missouriensis (A. DC.) Fern. [18]. LIFE FORM : Shrub FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


SPECIES: Corylus americana
GENERAL DISTRIBUTION : American hazelnut occurs from Maine west to Saskatchewan, south to eastern Oklahoma, east to Georgia, and north through New England [5,17,31]. ECOSYSTEMS :    FRES10  White - red - jack pine    FRES11  Spruce - fir    FRES14  Oak - pine    FRES15  Oak - hickory    FRES17  Elm - ash - cottonwood    FRES18  Maple - beech - birch    FRES19  Aspen - birch STATES :      AL  AR  GA  IL  IN  IA  KS  KY  LA  ME      MD  MA  MI  MN  MS  MO  NH  NJ  NY  NC      ND  OH  OK  PA  RI  SC  SD  TN  VT  VA      WV  WI  MB  ON  PQ  SK BLM PHYSIOGRAPHIC REGIONS :    14  Great Plains KUCHLER PLANT ASSOCIATIONS :    K081  Oak savanna    K093  Great Lakes spruce - fir forest    K095  Great Lakes pine forest    K099  Maple - basswood forest    K100  Oak - hickory forest    K101  Elm - ash forest    K103  Mixed mesophytic forest    K104  Appalachian oak forest    K106  Northern hardwoods    K108  Northern hardwoods - spruce forest    K100  Oak - hickory forest    K111  Oak - hickory - pine forest    K112  Southern mixed forest SAF COVER TYPES :      1  Jack pine      5  Balsam fir     12  Black spruce     13  Black spruce - tamarack     14  Northern pin oak     15  Red pine     16  Aspen     17  Pin cherry     18  Paper birch     20  White pine - northern red oak - red maple     21  Eastern white pine     22  White pine - hemlock     23  Eastern hemlock     24  Hemlock - yellow birch     25  Sugar maple - beech - yellow birch     26  Sugar maple - basswood     27  Sugar maple     30  Red spruce - yellow birch     31  Red spruce - sugar maple - beech     32  Red spruce     35  Paper birch - red spruce - balsam fir     39  Black ash - American elm - red maple     40  Post oak - blackjack oak     42  Bur oak     43  Bear oak     44  Chestnut oak     51  White pine - chestnut oak     52  White oak - black oak - northern red oak     53  White oak     55  Northern red oak     57  Yellow-poplar     58  Yellow-poplar - eastern hemlock     59  Yellow-poplar - white oak - northern red oak     60  Beech - sugar maple     62  Silver maple - American elm     76  Shortleaf pine - oak     78  Virginia pine - oak    108  Red maple    110  Black oak SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : American hazelnut is a dominant or codominant shrub in maple-basswood (Acer-Tilia) forests of Wisconsin and Minnesota [12].  In Nebraska, American hazelnut is a dominant shrub in the ecotone of forest and prairie [1,33].  It is a dominant understory species in jack pine (Pinus banksiana), paper birch (Betula papyrifera), trembling aspen (Populus tremuloides), and northern pin oak (Quercus ellipsoidalis) communities of northern Wisconsin [4].


SPECIES: Corylus americana
IMPORTANCE TO LIVESTOCK AND WILDLIFE : The leaves, twigs, and catkins of American hazelnut are browsed by deer and moose [11,24].  The nuts are eaten by small mammals, northern bobwhite, ruffed grouse and other large birds, and deer [19.20].  Beaver eat the bark [20]. PALATABILITY : NO-ENTRY NUTRITIONAL VALUE : American hazelnut has a fairly high protein and energy value.  Percentage composition (dry weight) of the nuts is as follows [32]:      crude protein       25.81      crude fiber          2.10      available protein   23.25      calcium              0.28      phosphorus           0.39 COVER VALUE : NO-ENTRY VALUE FOR REHABILITATION OF DISTURBED SITES : NO-ENTRY OTHER USES AND VALUES : American hazelnut has been cultivated as an ornamental since 1798.  It is also commercially cultivated for nut production.  The sweet nuts may be eaten raw or ground and made into a cakelike bread [31].  The nuts were used by Native Americans to flavor soups [16]. OTHER MANAGEMENT CONSIDERATIONS : American hazelnut often competes with hardwoods and pines for light and moisture [25,27].  Because of shading and aggressive growth, it has long been recognized as a major deterrent to the successful regeneration of upland conifers [6]. American and beaked hazelnut (C. cornuta) are responsible for much of the failure of red pine (Pinus resinosa) regeneration in Minnesota [13]. American hazelnut can be controlled with herbicides [22,25].


SPECIES: Corylus americana
GENERAL BOTANICAL CHARACTERISTICS : American hazelnut is a large, deciduous, rhizomatous shrub from 3 to 10 feet (1-3 m) tall [5,9].  It has a straight trunk with spreading, ascending branches, and can form dense thickets. The leaves are 3 to 5 inches (8-12 cm) long.  The male catkins are 8 inches (20 cm) long, straight, slender, and regularly spaced along the upper stem.  The female flowers are tiny, almost completely enclosed by bracts, and near the end of the twigs.  The nuts are enclosed in two leafy bracts [20,28].  The roots are typically in the upper 6 inches (15 cm) of soil [6].  Some of the smaller roots run vertically toward the surface and branch profusely into very fine laterals [34]. RAUNKIAER LIFE FORM :       Phanerophyte REGENERATION PROCESSES : American hazelnut reproduces both sexually and asexually.  It begins producing seed after the first year, and produces good seed crops every 2 to 3 years.  Seed dispersal is chiefly by mammals or birds [5]. Vegetative Reproduction:  The most important mode of reproduction of American hazelnut is from rhizomes [6].  The large, woody rhizomes are 4 to 6 inches (10-15 cm) below the surface.  Rhizomes give rise to new shoots 1 to 2 feet (30-60 cm) from the parent plant [34]. SITE CHARACTERISTICS : American hazelnut occurs along streams, hedgerows, meadows, woodlands, roadsides, and forest margins.  It grows best on rich, moist, well-drained soils [20,31,34] Common understory associates of American hazelnut include shagbark hickory (Carya ovata), raspberry (Rubus spp.), smooth sumac (Rhus glabra), chokecherry (Prunus virginiana), arrowwood (Viburnum rafinesquianum), eastern hophornbeam (Ostrya virginiana), and dogwood (Cornus spp.) [1,2,10]. SUCCESSIONAL STATUS : American hazelnut is shade tolerant [33].  It can grow under a light intensity of 15 percent or less; even as low as 1 percent [1].  It is a mid-seral species, and is usually absent in old-growth forest communities [2]. SEASONAL DEVELOPMENT : The flowers of American hazelnut are formed in the summer and open the following spring, before the leaves emerge.  By late summer or early fall, the fertilized flowers develop into fruits [5].


SPECIES: Corylus americana
FIRE ECOLOGY OR ADAPTATIONS : Low- to moderate-severity fires top-kill American hazelnut [7].  It survives fire by sprouting from rhizomes [7,10]. The underground roots and rhizomes can survive low- to moderate-severity fires when the humus is moist.  They are relatively shallow, however, and are vulnerable to fire when the humus is dry and combustible [6]. POSTFIRE REGENERATION STRATEGY :    Rhizomatous shrub, rhizome in soil    Secondary colonizer - off-site seed


SPECIES: Corylus americana
IMMEDIATE FIRE EFFECT ON PLANT : The aerial portions of American hazelnut are easily top-killed by spring and summer fires [7]. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : American hazelnut sprouts from rhizomes following fire [6]. Annual burning can help control American hazelnut. On oak woodland sites in Minnesota, a series of annual fires reduced the American hazelnut frequency to 39 percent on burned plots compared to 65 percent on unburned plots.  Although annual burning increased the density of hazelnut stems, stems on burned sites were shorter and smaller than stems on unburned sites, so total American hazelnut biomass was less on burned sites [3]. See Fire Case Studies for more information on this study. A volume equation for determining biomass, growth response, and woody density for American hazelnut following fire has been developed [8]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : In areas where fire has been excluded, a heavy density of American hazelnut has developed, suppressing desirable tree species and contributing to fuel buildup [10,21]. Repeated summer fires inhibit the ability of American hazelnut to sprout by exposing and damaging underground stems and roots and exhausting stored food reserves.  Single fires may eliminate American hazelnut if humus is sufficiently dry to be completely consumed [6].


Effects of repeated prescribed fires at Cedar Creek Natural History Area, Minnesota

SPECIES: Corylus americana

Fryer, Janet L., compiler. 2007. Effects of repeated prescribed fires at Cedar Creek Natural History Area, Minnesota. In: Corylus americana. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: [ ].

This Fire Case Study contains information on the following species:

Common name Scientific name
American hazelnut Corylus americana

Unless otherwise indicated, the information in this Fire Case Study comes from the following paper:

Axelrod, A. N.; Irving, F. D. 1978. Some effects of prescribed fire at Cedar Creek Natural History Area. Journal of the Minnesota Academy of Science. 44(2): 9-11. [3].

Prescribed burning was conducted on the Cedar Creek Natural History Area in Anoka and Isanti counties, Minnesota.

The study sites are on Anoka sand plain upland soils, with fine sands in the Sartell and Zimmerman series. Topography is generally level [3].

Cedar Creek Natural History Area contains bur oak-northern pin oak-quaking aspen (Quercus macrocarpa-Q. ellipsoidalis-Populus tremuloides) woodlands [35], marshlands, and old fields. The study sites were on the oak woodlands. American hazelnut clones dominated the understory, and there was an herbaceous ground layer. Based on the unburned control plots, prefire American hazelnut density was approximately 11 stems/milacre [3].

Study sites are classified in the following plant community and likely experienced the historic fire regime described below:

Fire regime information on the vegetation community in which American hazelnut occurs in this study. Fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Model [38]. This vegetation model was developed by local experts using available literature, local data, and expert opinion as documented in the .pdf file linked from the Potential Natural Vegetation Group listed below.
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
Minimum interval
Maximum interval
Northern oak savanna Replacement 4% 110 50 500
Mixed 9% 50 15 150
Surface or low 87% 5 1 20
*Fire Severities: Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Surface or low=Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects [36,37].

American hazelnut phenology was not described. American hazelnut was probably rapidly elongating its stems during the spring fires and flowering during the summer fires.

Spring/low and moderate severity
Summer/moderate severity

Fire Management Objective: Various repeat prescribed fire treatments were conducted to open stand structure in Cedar Creek's oak woodland. Prescribed burning was conducted over an 8-year period. The specific management objective was to reduce American hazelnut presence in the understory.

Fire prescription and behavior: Four fire treatment sites and an unburned control were selected for this study. Prescribed burning was conducted annually or on fire-and-rest cycles. A total of 19 prescribed fires were conducted on the 4 burn units. Seventeen of the fires were conducted in spring, with the earliest fire on 11 April 1969 and the latest on 16 May 1972. Surface fuels were oak litter and grasses (Poaceae). Fires on spring-burned sites were conducted before green-up, when surface fuels were mostly or completely cured. The majority of the prescribed fires were of moderate severity and fairly continuous; however, Site 3 experienced 2 low-severity, patchy summer fires before the moderate-severity April 1969 fire gave satisfactory fire continuity. April and May fires were ignited in the late afternoon, usually after 5:00 p.m., 3 to 10 days after measurable precipitation.  Strip head fires were used.

Stocking and treatment dates of prescribed-burn sites on Cedar Creek, MN
Site Treatment Area (acres) 1972 basal area (ft) Rx fire dates
Site 1 7 burns in 8 years 27 70 4 May 1965,
25 April 1966,
11 April 1967,
26 April 1968,
12 May 1969,
12 April 1971,
16 May 1972
Site 2 8 burns in 8 years 25 42 4 May 1965,
13 April 1966,
5 May 1967,
26 April 1968,
12 May 1969,
4 May 1970,
3 May 1971,
25 April 1972
Site 3 3 burns in 7 years 10 64 30 August 1966,
6 September 1967,
23 April 1969
Site 4 1 burn in 5 years 27 61 14 May 1969
Site 5 unburned control not provided 60 no recent fires

Weather conditions on days of burning ranged as follows:

Weather conditions and fire behavior for the Cedar Creek burns
Air temperature Relative humidity Windspeed Rate of spread Fuel consumption Flame height* Depth of flame front*
56-91 F 26%-72% 1-20 mph 8-15 ft/min 917-6,500 lbs/acre ~2 in-3 ft <1ft in grass fuels

~3 feet in thick oak litter

*Flame height and flame front measures are for spring fires only. These measures were not provided for the summer fire on Site 3.

Green-up had begun on some sites burned in late spring,, so herbaceous surface fuels were only partially cured. These late spring fires burned at lower severities, had slower rates of spread, and produced more smoke than the other spring fires.

All the spring fires top-killed American hazelnut clones. Duration of flame contact with American hazelnut stems was usually less than 1 minute, which was enough to kill the cambium of aboveground stems. American hazelnut stems on sites with heavy concentrations of fallen branches and other downed woody debris from wind-damaged oaks remained in direct contact with flames for as long as 10 minutes. Effects of this longer-burning woody debris on American hazelnut's underground system were not noted. Effects of the fires on stand structure and American hazelnut growth are shown below.

Overstory density and American hazelnut density, height, and biomass on study plots in the 4th postfire growing season. Data are means (SD).
Treatment Oak overstory basal area (ft/acre) American hazelnut basal area (stems/0.001 acre) Stem height* (inches) Stem biomass (g)
Site 1 (7 burns in 8 years) 70 (46) 19.2 (4.6) 16 (6.1) 16.3 (3.6)
Site 2 (8 burns in 8 years) 42 (68) 19.9 (8.4) 18 (6.1) 30.6 (16.4)
Site 3 (3 burns in 7 years) 64 (39) 8.0 (2.7) 34 (14) 117 (92.2)
Site 4 (1 burn in 5 years) 61 (51) 10.0 (6.2) 30 (9.4) 92.1 (49.4)
Site 5 (unburned control) 60 (44) 11.0 (4.6) 33 (14.2) 150.4 (85.3)
*For American hazelnut stem height, data are the means of the longest stem on each of 218 plots.

Statistical analyses showed no significant differences (P=0.05 for all study measures) between either American hazelnut density or stem height on Sites 1 and 2, the annual burn treatments. Similarly, there were no significant differences in stem density or stem height between Sites 3 and 4, the treatments with rest years between fire treatments. Data for the 2 annual fire treatments were therefore pooled and compared to pooled data for the 2 fire-and-rest treatments. American hazelnut stocking was significantly denser on annually burned plots (Sites 1 and 2) compared to fire-and-rest plots (Sites 3 and 4), and American hazelnut stems were significantly taller on fire-and-rest plots (Sites 3 and 4) compared to annually burned plots. The authors attribute these differences to age variation in American hazelnut stems. Annually burned plots had only even-aged, 1-year-old stems. As time since fire increased on fire-and-rest plots, even-aged stems from the first postfire growing season were augmented with younger, shorter stems.

Both annual fire and fire-and-rest treatments initially reduced American hazelnut stem density and height compared to the control; however, by fourth growing season following 1 to 3 fires, there were no significant differences between American hazelnut density, stem height, or biomass on fire-and-rest plots compared to unburned plots. However, the series of annual fires approximately doubled American hazelnut density and reduced mean stem height to about one-half that of American hazelnut stems on unburned plots. Stems on unburned plots were older and larger than stems on burned plots, so biomass of unburned stems was approximately 4 times more than biomass of stems on annually burned plots.

Fire management objective: The series of annual fires successfully controlled American hazelnut. Although density increased, the proportion of the understory occupied by American hazelnut was less due to reductions in height and biomass. Fire-and-rest treatments did not control American hazelnut.

Statistical analyses of the effects of the various fire treatments on the oak overstory were not provided. Based on overstory oak basal area, overstory stand structures were similar on fire-and-rest plots and control plots. The Site 1 annual burn plots had greater oak density than the fire-and-rest and control plots, while overstory density on the Site 2 annual burn plots was less than fire-and-rest and control plots. Further burning treatments on Cedar Creek and restoration fires on similar oak woodland/American hazelnut sites may help explain discrepancies in these study results.

Fire control of American hazelnut: The authors recommend repeated burning on a regular schedule to restore and maintain oak savannas. Field observations by the authors suggested that grass and forb cover increased where American hazelnut height and biomass were reduced by annual burning. The effect of repeated fires on American hazelnut was temporary, however. In this study, American hazelnut regained most of its prefire biomass by the fourth postfire growing season on fire-and-rest sites. Axelrod and Irving [3] predict that if burning is conducted at less than 7-year intervals, American hazelnut will completely regain its prefire height and biomass. The results of this study suggest that a schedule of annual or nearly annual fires provides optimal American hazelnut control.


SPECIES: Corylus americana
REFERENCES :  1.  Aikman, John M. 1926. Distribution and structure of the forests of        eastern Nebraska. University Studies. 26(1-2): 1-75.  [6575]  2.  Alban, David H.; Perala, Donald A.; Schlaegel, Bryce E. 1978. Biomass        and nutrient distribution in aspen, pine, and spruce stands on the same        soil type in Minnesota. Canadian Journal of Forest Research. 8: 290-299.        [16911]  3.  Axelrod, A. N.; Irving, F. D. 1978. Effects of prescribed fire on        American hazel at the Cedar Creek natural area in Minnesota. Restoration        and Management Notes. 1(2): 14.  [2850]  4.  Bockheim, J. G.; Jepsen, E. A.; Heisey, D. M. 1991. Nutrient dynamics in        decomposing leaf litter of 4 tree species on a sandy soil in        northwestern Wisconsin. Canadian Journal of Forest Research. 21:        803-812.  [14999]  5.  Brinkman, Kenneth A. 1974. Corylus L.  hazel, filbert. In: Schopmeyer,        C. S., technical coordinator. Seeds of woody plants in the United        States. Agric. Handb. 450. Washington, DC: U.S. Department of        Agriculture, Forest Service: 343-345.  [7594]  6.  Buckman, Robert E. 1964. Effects of prescribed burning on hazel in        Minnesota. Ecology. 45(3): 626-629.  [12204]  7.  Buckman, Robert E. 1965. Silvicultural use of prescribed burning in the        Lake States. In: Proceedings--Society of American Foresters meeting;        1964 September 27 - October 1; Denver, CO. Washington, D.C.: Society of        American Foresters: 38-40.  [8749]  8.  Buckman, Robert E. 1966. Estimation of cubic volume of shrubs (Corylus        spp.). Ecology. 47(5): 858-860.  [18746]  9.  Chapman, William K.; Bessette, Alan E. 1990. Trees and shrubs of the        Adirondacks. Utica, NY: North Country Books, Inc. 131 p.  [12766] 10.  Clark, James S. 1990. Twentieth-century climate change, fire        suppression, and forest production and decomposition in northwestern        Minnesota. Canadian Journal of Forestry Research. 20: 219-232.  [11646] 11.  Dalke, Paul D. 1941. The use and availability of the more common winter        deer browse plants in the Missouri Ozarks. Transactions, 6th North        American Wildlife Conference. 6: 155-160.  [17044] 12.  Eggler, Willis A. 1938. The maple-basswood forest type in Washburn        County, Wisconsin. Ecology. 19(2): 243-263.  [6907] 13.  Eyre, F. H., ed. 1980. Forest cover types of the United States and        Canada. Washington, DC: Society of American Foresters. 148 p.  [905] 14.  Eyre, F. H.; Zehngraff, Paul. 1948. Red pine management in Minnesota.        Circular No. 778. Washington, DC: U.S. Department of Agriculture. 70 p.        [12177] 15.  Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].        1977. Vegetation and environmental features of forest and range        ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of        Agriculture, Forest Service. 68 p.  [998] 16.  Gilmore, Melvin Randolph. 1919. Uses of plants by the Indians of the        Missouri River region. 33rd Annual Report. Washington, DC: Bureau of        American Ethnology. 154 p.  [6928] 17.  Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of        northeastern United States and adjacent Canada. 2nd ed. New York: New        York Botanical Garden. 910 p.  [20329] 18.  Great Plains Flora Association. 1986. Flora of the Great Plains.        Lawrence, KS: University Press of Kansas. 1392 p.  [1603] 19.  Gullion, G. W. 1970. Ruffed grouse investigations - influence of forest        management practices on grouse populations. Upland Game Job No. 45. [St.        Paul, MN]: Minnesota Department of Game and Fish. Game Research        Quarterly Reports. 30(3): 104-105.  [16748] 20.  Hunter, Carl G. 1989. Trees, shrubs, and vines of Arkansas. Little Rock,        AR: The Ozark Society Foundation. 207 p.  [21266] 21.  Paulsen, Harold A., Jr.; Miller, John C. 1968. Control of Parry        rabbitbrush on mountain grasslands of western Colorado. Journal of Range        Management. 21: 175-177.  [1844] 22.  Krefting, Laurits W. 1962. Use of silvicultural techniques for improving        deer habitat in the Lake States. Journal of Forestry. 60(1): 40-42.        [17092] 23.  Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation        of the conterminous United States. Special Publication No. 36. New York:        American Geographical Society. 77 p.  [1384] 24.  Pastor, J.; Dewey, B.; Naiman, R. J.; [and others]. 1993. Moose browsing        and soil fertility in the boreal forests of Isle Royale National Park.        Ecology. 74(2): 467-480.  [20767] 25.  Perala, Donald A. 1971. Controlling hazel, aspen suckers, and mountain        maple with picloram. Res. Note NC-129. St. Paul, MN: U.S. Department of        Agriculture, Forest Service, North Central Forest Experiment Station. 4        p.  [3953] 26.  Raunkiaer, C. 1934. The life forms of plants and statistical plant        geography. Oxford: Clarendon Press. 632 p.  [2843] 27.  Shirley, Hardy L. 1932. Light intensity in relation to plant growth in a        virgin Norway pine forest. Journal of Agricultural Research. 44:        227-244.  [10360] 28.  Stephens, H. A. 1973. Woody plants of the North Central Plains.        Lawrence, KS: The University Press of Kansas. 530 p.  [3804] 29.  Stickney, Peter F. 1989. Seral origin of species originating in northern        Rocky Mountain forests. Unpublished draft on file at: U.S. Department of        Agriculture, Forest Service, Intermountain Research Station, Fire        Sciences Laboratory, Missoula, MT; RWU 4403 files. 7 p.  [20090] 30.  U.S. Department of Agriculture, Soil Conservation Service. 1982.        National list of scientific plant names. Vol. 1. List of plant names.        SCS-TP-159. Washington, DC. 416 p.  [11573] 31.  Vines, Robert A. 1960. Trees, shrubs, and woody vines of the Southwest.        Austin, TX: University of Texas Press. 1104 p.  [7707] 32.  Wainio, Walter W.; Forbes, E. B. 1941. The chemical composition of        forest fruits and nuts from Pennsylvania. Journal of Agricultural        Research. 62(10): 627-635.  [5401] 33.  Weaver, J. E. 1968. Prairie plants and their environment: A fifty-year        study in the Midwest. Lincoln, NE: University of Nebraska Press. 276 p.        [17547] 34.  Weaver, J. E.; Kramer, Joseph. 1932. Root system of Quercus macrocarpa        in relation to the invasion of prairie. Botanical Gazette. 94: 51-85.        [274] 35.  Dijkstra, Feike A.; Wrage, Keith; Hobbie, Sarah E.; Reich, Peter B. 2006.        Tree patches show greater N losses but maintain higher soil N        availability than grassland patches in a frequently burned oak savanna.        Ecosystems. 9(3): 441-452.  [66022] 36.  Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005.        Interagency fire regime condition class guidebook. Version 1.2,        [Online]. In: Interagency fire regime condition class website. U.S.        Department of Agriculture, Forest Service; U.S. Department of the        Interior; The Nature Conservancy; Systems for Environmental Management        (Producer). Variously paginated [+ appendices]. Available: [2007, May 23].        [66734] 37.  LANDFIRE Rapid Assessment. 2005. Reference condition modeling        manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement        04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S.        Department of Agriculture, Forest Service; U.S. Department of the        Interior (Producers). 72 p. Available:        [2007, May 24].  [66741] 38.  LANDFIRE Rapid Assessment. 2007. Rapid assessment reference        condition models. In: LANDFIRE. U.S. Department of Agriculture, Forest        Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S.        Geological Survey; The Nature Conservancy (Producers). Available:  [66533]

FEIS Home Page