Index of Species Information

SPECIES:  Thuja occidentalis

Introductory

SPECIES: Thuja occidentalis
AUTHORSHIP AND CITATION : Carey, Jennifer H. 1993. Thuja occidentalis. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].
ABBREVIATION : THUOCC SYNONYMS : None SCS PLANT CODE : THOC2 COMMON NAMES : northern white-cedar northern whitecedar white-cedar white cedar eastern white-cedar eastern arborvitae arborvitae arbor vitae swamp-cedar TAXONOMY : The currently accepted scientific name for northern white-cedar is Thuja occidentalis L. [33]. LIFE FORM : Tree FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


DISTRIBUTION AND OCCURRENCE

SPECIES: Thuja occidentalis
GENERAL DISTRIBUTION : Northern white-cedar occurs in southeastern Canada and the adjacent northern United States. It is distributed from southwestern Nova Scotia, Prince Edward Island, New Brunswick, the Gaspe Peninsula in Quebec, and Anticosti Island in the Gulf of Saint Lawrence; west to northern Ontario and southeastern Manitoba; south to southeastern Minnesota and northern Illinois; and east through extreme northwestern Indiana, Michigan, and the New England states. Island populations occur in the Appalachian Mountains in western Pennsylvania, West Virginia, Virginia, and eastern Tennessee. Local populations also occur in west-central Manitoba, Wisconsin, Minnesota, Illinois, and Ohio [26,33]. Historical evidence indicates that northern white-cedar is native to North Carolina as well, but no known native population occurs there now [10]. ECOSYSTEMS : FRES10 White - red - jack pine FRES11 Spruce - fir FRES17 Elm - ash - cottonwood FRES18 Maple - beech - birch STATES : CT HI IL IN ME MD MA MI MN NH NY OH PA RI TN VT VA WV WI MB NB NS ON PE PQ BLM PHYSIOGRAPHIC REGIONS : NO-ENTRY KUCHLER PLANT ASSOCIATIONS : K093 Great Lakes spruce - fir forest K094 Conifer bog K095 Great Lakes pine forest K096 Northeastern spruce - fir forest K101 Elm - ash forest SAF COVER TYPES : 5 Balsam fir 12 Black spruce 13 Black spruce - tamarack 21 Eastern white pine 23 Eastern hemlock 24 Hemlock - yellow birch 30 Red spruce - yellow birch 32 Red spruce 33 Red spruce - balsam fir 35 Paper birch - red spruce - balsam fir 37 Northern white-cedar 38 Tamarack 39 Black ash - American elm - red maple 108 Red maple SRM (RANGELAND) COVER TYPES : NO-ENTRY HABITAT TYPES AND PLANT COMMUNITIES : Northern white-cedar is an important species in the wet-mesic coniferous forests of the northern lowlands [14]. It is often present in the ecotone between sphagnum bog and upland hardwood communities [15]. It may dominate rich swamp forests, poor swamp forests, and the cedar string bog and fen complex [24]. The following published classifications list northern white-cedar as dominant or codominant: The vegetation of Wisconsin [14] Virgin plant communities of the Boundary Waters Canoe Area [37] Plant communities of Voyageurs National Park, Minnesota, U.S.A. [30] Habitat classification system for Upper Peninsula of Michigan and northeast Wisconsin [11] Classification and gradient analysis of forest vegetation of Cape Enrage, Bic Park, Quebec [49] The principal plant associations of the Saint Lawrence Valley [16]

MANAGEMENT CONSIDERATIONS

SPECIES: Thuja occidentalis
WOOD PRODUCTS VALUE : The wood of northern white-cedar is resistant to decay. It is used for products that come in contact with water and soil, such as fence posts, shingles, paneling, and boats [25,26]. Northern white-cedar logs are especially popular to use for log cabins because the wood has good insulating qualities [31]. It is also used for kraft pulp and particle board [26]. IMPORTANCE TO LIVESTOCK AND WILDLIFE : Northern white-cedar provides food and shelter for wildlife. White-tailed deer, snowshoe hares, and porcupines heavily browse the foliage [26]. Northern white-cedar is one of the best winter browse species for white-tailed deer in the northern Lake States, and it is often overbrowsed [2]. Moose browse northern white-cedar only when other food is scarce. In a study on Isle Royale in Michigan, northern white-cedar constituted only 0.7 percent of the moose diet, but 5.8 percent of the available food [3]. Pileated woodpeckers feed on carpenter ants that, in turn, nest in and feed on the heartwood of northern white-cedar [13]. Other birds that are especially abundant in northern white-cedar forests include white-throated sparrows, golden-crowned kinglets, yellow-bellied flycatchers, ovenbirds, northern parulas, winter wrens, Swainson's thrushes, and numerous warblers. Blackburnian warblers, Cape May warblers, ovenbirds, and golden-crowned kinglets breed in the densest stands [18]. PALATABILITY : Northern white-cedar browse is highly palatable to white-tailed deer [2]. NUTRITIONAL VALUE : Northern white-cedar browse is, on average by wet weight, 2.7 percent protein, 5.2 percent fat, 27.5 percent carbohydrates, and 13.9 percent crude fiber [44]. It is high in calcium [29]. The browse is considered highly nutritious [2] and is more digestible to white-tailed deer than bigtooth aspen (Populus grandidentata) browse [44]. COVER VALUE : Stands of northern white-cedar provide thermal cover for white-tailed deer, moose, and black bear [4,9,39]. VALUE FOR REHABILITATION OF DISTURBED SITES : NO-ENTRY OTHER USES AND VALUES : Northern white-cedar is widely planted as an ornamental. Northern white-cedar leaf oil is distilled from boughs and used for perfume and medicines. The foliage is rich in vitamin C; Native Americans and early European explorers used it to treat scurvy [26]. Because of its long life span, northern white-cedar is a valuable species for dendroclimatic research [5]. OTHER MANAGEMENT CONSIDERATIONS : There is interest in regenerating northern white-cedar after harvest because of its forage value to white-tailed deer and because of the popularity of northern white-cedar log cabins. In the past, forest managers have not successfully regenerated this species. Northern white-cedar is a slow-growing species, and seedlings are frequently damaged by heavy browsing. Many former northern white-cedar stands are now dominated by balsam fir (Abies balsamea), spruce (Picea spp.), aspen (Populus spp.), or speckled alder (Alnus rugosa) [31]. A combination of clearcut and shelterwood strips is currently recommended for harvesting mature stands of northern white-cedar and reproducing new ones, although other possible methods should be investigated [27]. If there are less than 10 northern white-cedar advance regeneration stems per miliacre (2.5 stems/sq m), a prescribed fire after clearcutting is recommended to eliminate heavy slash, set back competition, and prepare a seedbed [27,31,46]. See FIRE EFFECTS for further details on the influence of fire on regeneration. Sapling stands provide the most browse for deer [26]. Overbrowsing can retard the growth and even kill a tree if it is less than 7 feet (2.1 m) tall [2]. A high browse line is frequently evident on larger trees [9]. Fifteen to twenty percent annual usage of foliage might maintain a constant food supply and still permit a suitable growth rate for saplings [2]. Thinning of stands improves deer habitat and timber quality [18]. Northern white-cedar is relatively free of serious insect injury. The principal pests are arborvitae leafminer (Argyresthia thuiella) and black and red carpenter ants (Camponotus pennsylvanicus and C. ferrugineus). Northern white-cedar is affected by few serious diseases [26]. Higher than normal water levels will reduce growth and eventually kill trees. Beaver damming and road construction are often responsible for impeded drainage [26,27].

BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Thuja occidentalis
GENERAL BOTANICAL CHARACTERISTICS : Northern white-cedar is a monoecious, native, evergreen tree with a narrow, almost columnar crown. Branches on open-grown trees extend to the ground. The trunk is often divided into two or more secondary trunks of equal size. Northern white-cedar has scalelike foliage and fibrous, sometimes shredding bark [25,26]. At maturity northern white-cedar is 40 to 50 feet (12-15 m) tall and 12 to 24 inches (30-60 cm) in d.b.h. Infrequently it reaches heights of 70 to 80 feet (21-24 m) and diameters of 48 to 60 inches (120-150 cm) [26]. This species is extremely slow growing; after 50 years, it might reach 40 feet (12 m) in height on good sites, but only 15 feet (4.6 m) or less on poor sites [27]. Northern white-cedar reaches ages in excess of 800 years [5,32]. Two trees on the Niagara Escarpment in southern Ontario were dated at 935 and 1,032 years [32]. Seedlings develop deep roots in well-drained soil and shallow roots in saturated soil. With age, northern white-cedar develops a widespreading root system which is well adapted to secure water and nutrients from cracks in rocks [26]. RAUNKIAER LIFE FORM : Phanerophyte REGENERATION PROCESSES : Sexual reproduction: Northern white-cedar begins producing cones as young as 6 years of age and begins producing large quantities by age 30. The best production occurs after age 75. Good crops occur at 2- to 5-year intervals with intervening years having fair to medium crops. Seeds have lateral wings and are disseminated by wind. Seeds are dispersed a distance of 150 to 200 feet (45-60 m) from the source tree [13,14,26]. Germination occurs when daytime temperatures reach about 84 degrees Fahrenheit (29 deg C) [21]. Northern white-cedar germinates on a variety of substrates including both mineral and organic soils, but seedling establishment is limited to sites with a constant moisture supply [26]. Drought is a major cause of seedling mortality [14]. Seedlings that germinate on old stumps are likely to die when the stumps dry out in late summer, and seedlings that germinate in fast-growing sphagnum moss (Sphagnum spp.) may be smothered [13]. Seedlings prosper on recently burned sites [26]. Seedling growth is slow. Annual height growth averages 3 inches (8 cm) in the first few years. Partial light is needed for continued seedling growth [26]. Vegetative reproduction: Under favorable moisture conditions, northern white-cedar reproduces vegetatively by layering. Seedlings may reproduce by layering at age 5 or earlier. Layering accounts for a considerable amount of northern white-cedar reproduction. It is common in swamp forests where trees often fall or tip slowly. Trees established on logs and stumps may fall as their weight increases and the substrate rots [13,14,26]. Branches on a fallen tree that still has functional roots may begin growing vertically. Eventually, with the increased weight of new growth, the stem will contact the soil and put out adventitious roots [13]. SITE CHARACTERISTICS : Northern white-cedar grows on both uplands and lowlands. The uplands are primarily seepage areas, old fields, and limestone cliffs and boulder fields. The lowland sites include swamps, streambanks, and lakeshores. Northern white-cedar occurs from near sea level to more than 2,000 feet (600 m) in elevation. It grows up to 4,270 feet (1,300 m) in the Adirondack Mountains in New York on sites where water is flowing over rocks [26]. On lowland sites, northern white-cedar generally grows where there is a strong flow of moderately mineral-rich soil water of near neutral pH (minerotrophic and weakly minerotrophic swamps) and where the organic peat is moderately to well decomposed. The peat is usually 1 to 6 feet (0.3-1.8 m) thick and contains rotten wood. Northern white-cedar grows best where soils are neutral to moderately alkaline [19,24,26]. On upland sites, northern white-cedar grows primarily in calcareous soils including calcareous clays and shallow loam overlying broken limestone [26]. Habeck [50] has suggested that northern white-cedar growing in limestone uplands is an ecotype distinct from wet lowland northern white-cedar. Specimens growing on cliffs tend to be deformed with multiple leaders and twisted trunks, whereas those in wet lowlands tend to be more erect with well-defined trunks. However, four studies that looked at tree morphology [8], seed morphology [7], growth patterns [36], and xylem water potential [12] found no evidence of ecotypic variation. There tended to be more variation within a single site than between lowland and upland sites. Seedlings, from seeds collected from the two contrasting habitats, were grown under different moisture conditions. Xerically grown seedlings had significantly (p<0.05) more negative xylem water potential than did seedlings grown under moist conditions, independent of seed origin. The seedlings acclimated to the conditions and demonstrated that northern white-cedar has broad physiological tolerance to habitat moisture [12]. Overstory associates not mentioned in DISTRIBUTION AND OCCURRENCE include white spruce (Picea glauca), quaking aspen (Populus tremuloides), balsam poplar (P. balsamifera), and bigtooth aspen. Shrub associates on good sites include speckled alder, mountain maple (Acer spicatum), red-osier dogwood (Cornus stolonifera), and American fly honeysuckle (Lonicera canadensis). Bog Labrador-tea (Ledum groenlandicum), blueberries (Vaccinium spp.), and wintergreen (Gaultheria procumbens) occur on poorer sites. Creeping wintergreen (G. hispidula) occurs on both good and poor sites [26]. Herbs that occur in swamps with northern white-cedar include dwarf red blackberry (Rubus pubescens), Canada mayflower (Maianthemum canadense), woodfern (Dryopteris spp.), bunchberry dogwood (Cornus canadensis), false Solomons-seal (Smilacina spp.), and pitcherplant (Sarracenia purpurea) [26]. Dwarf lake iris (Iris lacustris), a federally threatened species endemic to the northern shores of Lake Michigan and Lake Huron, is found in association with narrow beach strands of northern white-cedar [43]. The groundcover in northern white-cedar swamp forests includes sphagnum and other mosses, liverworts, decaying logs, and litter [26]. SUCCESSIONAL STATUS : Although northern white-cedar is generally considered shade tolerant, it is not as tolerant as balsam fir or sugar maple (Acer saccharum). Seedlings may only be intermediate in shade tolerance [13,26]. They can survive severe suppression for several years, but if not released, they die [26]. Vegetative shoots are more tolerant than seedlings. Although some authors [6,30,31] consider northern white-cedar a climax species because of its longevity and shade tolerance, it cannot reproduce by seed under dense shade to any marked extent [13]. Northern white-cedar will invade and form even-aged stands in old fields, openings created by windfall or cutting, and recently burned swamp sites. It replaces speckled alder thickets that form in swamps after fire or after changes in water levels [19,26]. Northern white-cedar is a pioneer on limestone cliffs and talus slopes. The roots grow in small pockets of organic material between rocks [49]. Northern white-cedar succeeds less tolerant, shorter lived species such as balsam poplar, tamarack (Larix laricina), and black spruce (Picea mariana) [26]. An uneven-aged old-growth northern white-cedar community occurs on the Niagara Escarpment in southern Ontario. This self-sustaining population occurs in a 3.3 to 16.4-foot (1-5 m) wide strip on the limestone cliff edge and face [32]. Uneven-aged stands also form on poor lowland sites where vegetative reproduction is the primary mode of reproduction [26]. Northern white cedar is often succeeded by sugar maple and other more shade-tolerant species [1,17]. Replacement is usually tree by tree, but major disturbance (excluding fire) can accelerate succession by releasing shade-tolerant species [balsam fir, sugar maple, black ash (Fraxinus nigra)] growing in the understory [1,19]. SEASONAL DEVELOPMENT : Flower buds form in autumn and expand the following spring. Pollen is dispersed from late April to June. Cones are full grown by mid-August, ripen in August and September, and open 7 to 10 days after ripening. Seeds germinate the following spring or early summer when sufficiently high temperatures occur [26].

FIRE ECOLOGY

SPECIES: Thuja occidentalis
FIRE ECOLOGY OR ADAPTATIONS : Northern white cedar is highly susceptible to fire because of thin bark, shallow roots, and high oil content [26]. In the understory of a pine, aspen, or birch (Betula spp.) forest, northern white-cedar acts as a fuel ladder, carrying fire into the overstory [23]. The risk of fire on most northern white-cedar sites is low, but fires occasionally originate on drier sites and spread into northern white-cedar stands [34]. Forested peatlands with a moss ground cover will not carry spring fires because of a high water table, but forested fens with a ground cover of sedges (Carex spp.) and grasses carry fire in the spring when the grasses and sedges are dry. Most fires in peatlands with a moss ground cover occur in July, August, or September. Given sufficient winds, northern white-cedar stands can carry a crown fire [22]. Northern white-cedar reproduces well on moist organic soils exposed by fire if a seed source is nearby. Many northern white-cedar forests in the Lake States originated after fire [14]. However, if the peat burns and the humus is destroyed, northern white-cedar may not become established for a long time [34]. Vogl [47] classifies northern white-cedar as a fire-initiated species in which fire simultaneously terminates and initiates a long-lived species. Fires are infrequent and usually severe. The longest lived specimens occur in locations where fire is infrequent or nonexistent because of rocky substrate, sparse ground cover, or low stand density [5]. Examples of such sites include the lakeshores and islands of Lake Duparquet, Quebec [6] and the Niagara Escarpment in Ontario [32]. Recurring fire may be responsible for the exclusion of northern white-cedar from some sites [6]. POSTFIRE REGENERATION STRATEGY : Tree without adventitious-bud root crown Secondary colonizer - off-site seed

FIRE EFFECTS

SPECIES: Thuja occidentalis
IMMEDIATE FIRE EFFECT ON PLANT : Northern white-cedar is usually killed by surface fire. Large trees may survive if ground cover is sparse. DISCUSSION AND QUALIFICATION OF FIRE EFFECT : NO-ENTRY PLANT RESPONSE TO FIRE : Northern white-cedar becomes established by seed on recently burned sites if a seed source is nearby and the exposed soil is moist [14,34,47]. Fire serves to remove competition and also removes the moss layer that dries out in the summer and results in seedling mortality [31]. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : NO-ENTRY FIRE MANAGEMENT CONSIDERATIONS : Prescribed fire is recommended after northern white-cedar harvest unless there is ample advance regeneration or if the organic soil is unsaturated. Fire removes the heavy slash that prevents regeneration and also prepares a favorable seedbed [27,46]. However, deep ground fires can start if the soil is not saturated [27]. If removing slash is the primary objective, prescribed fires are usually conducted under the following conditions: 3 to 10 days after a rainfall of more than 0.1 inch (0.3 cm), a minimum relative humidity of 30 to 60 percent, a maximum air temperature of 60 to 90 degrees Fahrenheit (16-32 deg C), and a maximum wind speed of 5 to 15 miles per hour (8-24 km/h). If the objective is to remove slash and prepare a seedbed, the fire must be hotter and is usually conducted under the following conditions: at least 7 days since a rainfall of more than 0.1 inch (0.3 cm), less than 45 percent relative humidity, air temperatures greater than or equal to 80 degrees Fahrenheit (27 deg C), and 5 to 15 miles per hour (8-24 km/h) wind speed [27]. The effect of three different slash treatments on northern white-cedar regeneration after winter clearcutting was investigated. The treatments were (1) a prescribed broadcast fire in August to burn the slash, (2) skidding entire trees out of the study area and delimbing elsewhere, and (3) leaving the slash in place. Five growing seasons after clearcutting, northern white-cedar less than or equal to 23.6 inches (60 cm) tall averaged 33.3 stems per miliacre (8.2 stems/sq m) on burned plots, and 11.5 and 22.2 stems per miliacre (2.8 and 5.5 stems/sq m) on full-tree skidded and slash-left plots, respectively. Ten growing seasons after clearcutting, northern white-cedar had increased to 40.2 stems per miliacre (9.9 stems/sq m) on burned plots but showed no change on the other treatment plots [46]. Northern white-cedar slash is a fire hazard for 20 to 30 years because of its resistance to decay [42]. Prescribed fire can be used to eliminate northern white-cedar that invades fens in the absence of fire. A low intensity fall fire (rarely exceeding 70 BTU/sec/sq ft) resulted in a statistically significant reduction in the percent cover of northern white-cedar for three postfire growing seasons. Annual prescribed burning is recommended for restoring fens [40,41].

REFERENCES

SPECIES: Thuja occidentalis
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Vegetatio. 79: 51-63. [5042] 7. Briand, Christopher H.; Posluszny, Usher; Larson, Douglas W. 1992. Comparative seed morphology of Thuja occidentalis (eastern white cedar) from upland and lowland sites. Canadian Journal of Botany. 70: 434-438. [18695] 8. Briand, Christopher H.; Posluszny, Usher; Larson, Douglas W.; Matthes-Sears, Uta. 1991. Patterns of architectural variation in Thuja occidentalis L. (eastern white cedar) from upland and lowland sites. Botanical Gazette. 152(4): 494-499. [18111] 9. Brown, David T.; Doucet, G. Jean. 1991. Temporal changes in winter diet selection by white-tailed deer in a northern deer yard. Journal of Wildlife Management. 55(3): 361-376. [15406] 10. Clebsch, Edward E. C. 1989. New distributional records of arbor vitae (Thuja occidentalis L.) in the Southeast, including the written evidence for North Carolina. In: Wood, James D., Jr., compiler. Abstracts, 15th annual scientific research meeting, 1989 May 25-26; Gatlinburg, TN. Atlanta, GA: U.S. Department of the Interior, National Park Service, Southeast Regional Office: 7. Abstract. [15208] 11. Coffman, Michael S.; Alyanak, Edward; Resovsky, Richard. 1980. Field guide habitat classification system: For Upper Peninsula of Michigan and northeast Wisconsin. [Place of publication unknown]: Cooperative Research on Forest Soils. 112 p. [8997] 12. Collier, Donald E.; Boyer, Michael G. 1989. The water relations of Thuja occidentalis L. from two sites of contrasting moisture availability. Botanical Gazette. 150(4): 445-448. [11637] 13. Curtis, James D. 1946. Preliminary observations on northern white cedar in Maine. Ecology. 27: 23-36. [19804] 14. Curtis, John T. 1959. The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press. 657 p. [7116] 15. Damman, Antoni W. H.; French, Thomas W. 1987. The ecology of peat bogs of the glaciated northeastern United States: a community profile. Biological Report 85(7.16). 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Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905] 20. 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] 21. Godman, Richard M.; Mattson, Gilbert A. 1976. Seed crops and regeneration problems of 19 species in northeastern Wisconsin. Res. Pap. NC-123. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 5 p. [3715] 22. Heinselman, Miron L. 1981. Fire intensity and frequency as factors in the distribution and structure of northern ecosystems. In: Mooney, H. A.; Bonnicksen, T. M.; Christensen, N. L.; [and others], technical coordinators. Fire regimes and ecosystem properties: Proceedings of the conference; 1978 December 11-15; Honolulu, HI. Gen. Tech. Rep. WO-26. Washington, DC: U.S. Department of Agriculture, Forest Service: 7-57. [4390] 23. Hein, David G.; Miller, Stephen D. 1992. Influence of leafy spurge on forage utilization by cattle. Journal of Range Management. 45(4): 405-407. [18810] 24. Heinselman, M. L. 1970. Landscape evolution, peatland types and the environment in the Lake Agassiz Peatlands Natural Area, Minnesota. Ecological Monographs. 40(2): 235-261. [8378] 25. Hosie, R. C. 1969. Native trees of Canada. 7th ed. Ottawa, ON: Canadian Forestry Service, Department of Fisheries and Forestry. 380 p. [3375] 26. Johnston, William F. 1990. Thuja occidentalis L. northern white-cedar. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 580-589. [13418] 27. Johnston, W. F. 1977. Manager's handbook for northern white cedar in the north central States. Gen. Tech. Rep. NC-35. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 18 p. [9197] 28. 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] 29. Kudish, Michael. 1992. Adirondack upland flora: an ecological perspective. Saranac, NY: The Chauncy Press. 320 p. [19376] 30. Kurmis, Vilis; Webb, Sara L.; Merriam, Lawrence C., Jr. 1986. Plant communities of Voyageurs National Park, Minnesota, U.S.A. Canadian Journal of Botany. 64: 531-540. [16088] 31. Lanasa, Mike. 1989. Northern white-cedar management and whitetail deer habitat. In: Proceedings of the National Silviculture Workshop: Silviculture for all resources; 1987 May 11-14; Sacramento, CA. Washington, DC: U.S. Department of Agriculture, Forest Service, Timber Management: 19-24. [8680] 32. Larson, D. W.; Kelly, P. E. 1991. The extent of old-growth Thuja occidentalis on cliffs of the Niagara Escarpment. Canadian Journal of Botany. 69: 1628-1636. [16602] 33. Little, Elbert L., Jr. 1979. Checklist of United States trees (native and naturalized). Agric. Handb. 541. Washington, DC: U.S. Department of Agriculture, Forest Service. 375 p. [2952] 34. Little, S. 1946. The effects of forest fires on the stand history of New Jersey's Pine Region. Forest Management Paper No. 2. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 43 p. [11619] 35. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings, Tall Timbers fire ecology conference and Intermountain Fire Research Council fire and land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496] 36. Matthes-Sears, Uta; Larson, Douglas W. 1991. 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Prescribed burning and other possible management tools for suppression of woody species in Maine ferns. Natural Areas Journal. 12(3): 155. [19405] 42. Scholtz, H. F. 1930. How long does hardwood slash remain a fire menace?. Journal of Forestry. 28: 568. [16386] 43. Simonich, M. T.; Morgan, M. D. 1990. Researchers successful in transplanting dwarf lake iris ramets. Restoration & Management Notes. 8(2): 131-132. [13758] 44. Ullrey, D. E.; Youatt, W. G.; Johnson, H. E.; [and others]. 1964. Digestibility of cedar and aspen browse for the white-tailed deer. Journal of Wildlife Management. 28(4): 791-797. [19801] 45. 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] 46. Verme, Louis J.; Johnston, William F. 1986. Regeneration of northern white cedar deeryards in Upper Michigan. Journal of Wildland Management. 50(2): 307-313. [18683] 47. Vogl, Richard J. 1977. Fire: a destructive menace or a natural process?. In: Cairns, J., Jr.; Dickson, K. L.; Herricks, E. E., eds. Recovery and restoration of damaged ecosystems: Proceedings of the international symposium; 1975 March 23-25; Blacksburg, VA. Charlottesville, VA: University Press of Virginia: 261-289. [10055] 48. Wang, B. S. P. 1974. Tree-seed storage. Publication No. 1335. Ottawa, Canada: Department of the Environment, Canadian Forestry Service. 32 p. [17267] 49. Zoladeski, C. A. 1988. Classification and gradient analysis of forest vegetation of Cape Enrage, Bic Park, Quebec. Le Naturaliste Canadien. 115(1): 9-18. [13610] 50. Habeck, James R. 1958. White cedar ecotypes in Wisconsin. Ecology. 39(3): 457-463. [11232]


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