Carya glabra, pignut hickory
Tirmenstein, D. A. 1991. Carya glabra, pignut hickory. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/cargla
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Plants | ||||
| CARGLA | pignut hickory | Carya glabra | Life Form: Plants/Tree Kingdom: Plantae Class: Dicot Order: Juglandales Family: Juglandaceae Genus: Carya | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The currently accepted scientific name of pignut hickory is Carya glabra (P.Mill.) Sweet. (Juglandaceae)[25].
The taxonomic relationship between C. glabra and C. ovalis is particularly difficult [32], and many taxonomists prefer to treat these sympatric taxa as a complex [51]. Many intermediates have been reported; some authorities treat C. ovalis as an interspecific hybrid between C. glabra and C. ovata [32,51].
Pignut hickory hybridizes with butternut hickory (C. cordiformis) [54]. Demaree hickory, C. X demareei Palmer, is a hybrid product of pignut hickory and butternut hickory.
Synonyms
- Carya glabra var. glabra
- Carya glabra var. hirsuta (Ashe) Ashe
- Carya glabra var. megacarpa (Sarg.) Sarg.
- Carya leiodermis Sarg.
- Carya magnifloridana Murrill
- Carya megacarpa Sarg.
- Carya microcarpa Nutt.
Other Common Names
broom hickory, swamp hickory, sweet pignut hickory, smoothbark hickory, coast pignut hickory, pignut, false shagbark
General Distribution
Pignut hickory grows from eastern Maine westward to southern Michigan, Illinois, and southeastern Iowa [17]. It extends southward to eastern Texas, Louisiana, and Arkansas, and eastward to central Florida [17,54]. It is common but not abundant throughout much of eastern North America [51]. Pignut hickory reaches greatest abundance in the Ohio River Basin and is the most common hickory of the Appalachian Mountains [51].
States and Provinces
- United States: AL AR CT DE FL GA IA IL IN KY LA MA MD MI MO NE NH NJ NY NC OH OK PA RI SC TN VA VT WV
Site Characteristics
Pignut hickory grows in mesic to xeric mixed woodlands, bottomland woodlands, wet hammocks, on stable dunes, and rocky hillsides [10,11,17,40]. It is a common component of southern mixed hardwood forests, flatwoods, and eastern redcedar (Juniperus virginiana) [18,40,42]. It is also common but rarely abundant in oak-hickory forests [51].
Plant associates: Various oaks, including post oak (Quercus stellata), southern red oak (Q. falcata), black oak (Q. velutinus), northern red oak, white oak, chestnut oak (Q. prinus), and blackjack oak (Q. marilandica), are common overstory associates [18,45]. Shortleaf pine (Pinus echinata), loblolly pine (P. taeda), bald cypress (Taxodium distichum), sweetgum (Liquidambar styraciflua), and water tupelo (Nyssa aquatica) also grow with pignut hickory [50]. Southern magnolia (Magnolia grandiflora), cabbage palmetto (Sabal palmetto), and redbay (Persea borbonia) are particularly common overstory associates in the South [8,50], whereas sugar maple (Acer saccharum), red maple (A. rubrum), black birch (Betula lenta), and yellow birch (B. alleghaniensis) frequently grow with pignut hickory in the northern portion of its range [15,24,59].
Understory associates of pignut hickory are both numerous and diverse and vary according to site and location [51]. In portions of the South, flowering dogwood (Cornus florida), sourwood (Oxydendrum arboreum), muscadine grape (Vitus rotundifolia), blueberries (Vaccinium spp.), rhododendron (Rhododendron spp.), and common greenbrier (Smilax rotundifolia) are common associates [5].
Climate: Pignut hickory occurs in a humid climatic regime [51].
Soils: Pignut hickory grows best on light, well-drained, loamy soils [41]. Soil fertility is variable [51]. It occurs on soils derived from a variety of metamorphic and sedimentary parent materials including limestone, granitic-basic and mica schist-phyllite, glacial till, and shale [17,18,51].
Elevation: Generalized elevational ranges by geographic location are as follows:
| Location | Elevation | Authority |
|---|---|---|
| southern Appalachians | > 2,952 feet (> 900 m) | Duncan and Duncan 1988 |
| Great Smoky Mountains | < 2,500-3,000 feet (763-915 m) | Whittaker 1954 |
| Great Smoky Mountains | up to 4,850 ft (1,480 m) | Smalley 1991 |
Plant Communities
Pignut hickory codominates certain upland hardwood forests of eastern North America. Common codominants include white oak (Quercus alba) and northern red oak (Q. rubra). Pignut hickory is included as a dominant or indicator in the following community type classifications (cts):
| Area | Classification | Authority |
|---|---|---|
| southwest Ohio | forest cts | Braun 1936 |
| Tennessee | general veg. cts | Quarterman and others 1972 |
Botanical Description
Pignut hickory.
Pignut hickory is a slow-growing deciduous tree which reaches 65 to 98 feet (20-30 m) in height and 11 to 39 inches (30-100 cm) in diameter [10,17,27,54]. On extremely favorable sites, individuals may reach 131 feet (40 m) in height [11]. Pignut hickory is characterized by a narrow oblong crown and somewhat pendulous branches [54]. The gray bark is shallowly ridged and furrowed [10,17]. Plants generally possess a pronounced taproot but few laterals [51].
Pignut hickory is monoecious [51]. Pistillate flowers are borne in two- to five-flowered spikes [27,54], which develop on the shoots of the current year [51]. Slender, staminate catkins averaging 2 to 3.1 inch (5-8 cm) in length are borne from the axils of leaves on the previous season or from the inner buds of terminal scales on the current year's growth [17,27,51]. The fruit of pignut hickory is a hard, pear-shaped nut [10,45]. The nut is thick-shelled and approximately 0.6 to 1.4 inches (1.5-3.5 cm) in length [27,54]. The husk splits about halfway to the base [10,45]. The small kernel is sweet to bitter [17,54].
Raunkiaer Life Form (Raunkiaer 1934)
- Phanerophyte
Seasonal Development
Across most of its range, pignut hickory flowers in April or May [2]. Staminate flowers typically develop before the pistillate flowers [51]. Fruit ripens during September or October as the husk splits part way to the base [2,27]. Seed dispersal occurs from September through December [51]. Flowering and fruit ripening dates by geographic location are as follows:
| Location | Flowering | Fruiting | Authority |
|---|---|---|---|
| southeast U.S. | April-May | — | Duncan & Duncan 1988 |
| southwest U.S. | April-May | September-October | Vines 1960 |
| New England | May 17-June 23 | — | Seymour 1985 |
| North Carolina, South Carolina | April-May | October | Radford and others 1968 |
Regeneration Processes
Pignut hickory regenerates through seed and by vegetative means.
Seed
Pignut hickory begins producing seed at approximately 30 years of age; maximum seed production generally occurs between 75 and 200 years of age [2,51]. Maximum age of seed production is approximately 300 years [51]. Good seed crops occur at 1- or 2-year intervals, but may be reduced by frost, insects, and seed-eating birds and mammals. Seed is dispersed by gravity and by birds and mammals [51,57]. Mammals such as squirrels and chipmunks are typically more effective dispersal agents than birds [57].
Germination
Seeds of pignut hickory exhibit embryo dormancy that can be broken by stratification at 33 to 40 degrees F (1-4 deg C) for 30 to 150 days [2]. Seeds rarely remain viable in the forest floor for more than one winter [51]. Early seedling growth is typically slow.
Pignut hickory sprouting from a cut stump.
Vegetative regeneration
Pignut hickory sprouts from the root or stump after plants are cut or top-killed by fire. Smalley [51] reported that sprouting "is not as prolific as in other deciduous tree species but sprouts that are produced are vigorous and grow rapidly in height." Sprouts may be killed by drought, frost, fire, or herbivory, but roots often survive and sprout from dormant buds located near the root collar or lower part of the stem [48]. Smaller diameter pignut hickories typically sprout more frequently than do larger trees. Sprouts that originate at or below the ground level tend to be less subject to decay than those that originate higher on the trees [51].
Successional Status
Pignut hickory is tolerant of shade in the Southeast, but relatively intolerant in the northeastern portion of its range [51]. It grows as a common codominant in climax communities of the North Carolina Plain [43] and occurs in climax hammock communities of Florida [14,53]. In parts of Florida, early seral pine-oak-hickory forests are replaced by mature oak-hickory stands [30]. Species such as southern magnolia, beech, cabbage palmetto, and redbay may ultimately assume prominence, but long-lived dominants such as pignut hickory commonly persist in climax stands [9]. Pignut hickory grows in climax white oak-hickory forests of southwestern Ohio, in old-growth oak-hickory forests of southern Michigan, and in low-elevation climax stands in parts of the southern Appalachians [4,21,59].
Heavy-seeded species such as pignut hickory are generally slow to invade new areas [18]. However, pignut hickory, along with various oaks (northern red oak, black oak, white oak), may replace early seral gray birch (Betula populifolia)-eastern redcedar stands in oldfield communities of New York [47]. More shade-tolerant species such as red maple (Acer rubrum) may ultimately replace oak and hickory. In some portions of the Appalachian Highlands, hickory may ultimately replace chestnut killed by chestnut blight [51].
Immediate Fire Effects
Pignut hickory is readily damaged by fire [51], but the specific effects of fire vary with topography, slope, aspect, and season of burn [34]. Seedlings are often top-killed by fire [35,48], while larger trees with thicker bark tend to be somewhat more resistant to fire. Ward and Stephens [56] reported that postfire mortality of hickory saplings was much greater than for sawtimber. Fires which occur when hickories are dormant tend to be less damaging [34].
The tight, solid bark of hickories tends to be more severely scarred by fire than the rough or corky bark of other species [26]. Once fire-scarred, trees often succumb to rot or fungi.
Postfire Regeneration Strategy (Stickney 1989)
- survivor species; on-site surviving root crown
- off-site colonizer; seed carried by animals or water; postfire yr 1 & 2
Fire Adaptations
Periodic fires favor oaks over less fire-resistant species such as hickories [23]. In the Northeast, reduced fire frequencies may have resulted in the conversion of oak-hickory forests to mixed mesophytic stands [56]. Fire suppression may have favored both hickories and beech throughout much of the Southeast. In the Great Smoky Mountains, fire suppression since the 1940's has allowed pignut hickory to reach fire-resistant sizes [23].
Pignut hickory commonly sprouts from the root crown or stem base after aboveground foliage is killed by fire. Seedling establishment may also occur as birds and mammals transport seed from off-site.
Plant Response to Fire
Hickories often sprout from the base after plants are top-killed by fire [35]. Seedlings commonly sprout from dormant buds located on the root collar or lower part of the stem [48]. Postfire increases in stem density have been reported, but recovery may be relatively slow [56]. Some seedling establishment may also occur.
After a late summer wildfire in a mixed hardwood stand of Connecticut, stems of sprout origin accounted for 31 percent of the total on unburned sites and 39 percent on burned plots [56]. Postfire increases in stem numbers are often described as "long-term." Fifty-five years after a summer wildfire, Ward and Stephens [56] reported greater "relative and absolute levels" of hickories on burned than on unburned plots.
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name or acronym on the home page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
Wildlife considerations: Scattered surviving hickories often develop large crowns and produce good nut crops. These trees may be particularly valuable for wildlife [35].
Mortality: Equations developed for black oak may be used to predict fire-caused mortality in pignut hickory [34].
Federal Status
None
Other Status
No entry.
Importance to Wildlife and Livestock
Browse: White-tailed deer occasionally browse pignut hickory, and small mammals may eat the leaves [51].
Nuts: Pignut hickory nuts provide food for the fox squirrel in many areas [33] and are preferred by the gray squirrel during fall and winter in parts of New York [31]. Hickory nuts may comprise up to 10 to 25 percent of squirrel diets in some locations [51]. The eastern chipmunk relies on hickory nuts for 5 to 10 percent of its diet [51]. Hickory nuts are also eaten by the black bear, gray fox, raccoon, red squirrel, pocket mouse, woodrat, and rabbits [27,51]. Hickory nuts are utilized by black bears at lower elevations in parts of New England during the fall; the abundance of such mast crops can affect black bear reproductive success during the following year [12]. Value to fur and game mammals is good [8].
Hickory nuts are eaten by many birds including the wood duck, ring-necked pheasant, northern bobwhite, wild turkey, American crow, blue jay, white-breasted nuthatch, red-bellied woodpecker, and yellow-bellied sapsucker [37]. The value of hickory nuts to upland game birds and songbirds is fair [8].
Palatability and Nutritional Value
Pignut hickory nuts are highly palatable; browse appears to be of low palatability.
Browse: The nutrient content of pignut hickory browse varies seasonally. Mean foliar ash content has been reported as 12.75 percent in the spring and 11.61 percent during the fall [28].
Nuts: Pignut hickory nuts are high in protein and fats [31]. Crude fat content may reach 70 to 80 percent in some species of hickory [51]. Nuts are moderate to low in phosphorus, and calcium and very low in crude fiber [51]. The nuts provide a relatively low rate of energy uptake for gray squirrels.
Cover Value
Pignut hickory presumably provides cover for a variety of birds and mammals. Many hickories are used as den trees by several species of squirrels [8].
Value for Rehabilitation or Restoration of Disturbed Sites
Pignut hickory may have potential value for use on some types of disturbed sites. It recolonizes abandoned strip mines in Maryland and West Virginia [22].
Pignut hickory can be readily propagated through seed. Cleaned seed averages 200 per pound (440/kg) [2]. Seed may be planted during the fall or stratified and planted in the spring. Pignut hickory is difficult to transplant or to propagate by cuttings [51,54].
Other Uses
Nuts of pignut hickory are large and edible [401 and in some areas are grown commercially, although they are of minor importance when compared to shagbark hickory nuts [20].
Pignut hickory is used as a shade tree throughout much of its range [51].
Wood Products Value: Pignut hickory wood is heavy, hard, strong, tough, and elastic [41,54]. Early uses included broomhandles, skis, wagon wheels and, early automobile parts [41,54]. Sporting goods, agricultural implements, and tool handles are made from the wood of pignut hickory [24,41,54]. Specialty products include shuttle blocks, mallets, and mauls [51].
Other Management Considerations
Insects/disease: Some diseases cause premature nut drop [3]. Insect and disease damage may be particularly severe and can result in the death of large tracts of timber during drought years [51].
Damage: Pignut hickory is windfirm and resists ice damage.
Mechanical treatment: Hickories commonly produce epicormic branches or water sprouts after pruning [7].
Chemical control: Pignut hickory is resistant to most herbicides [39], but good results have been obtained with Garlon [38,39].
Silviculture: Following timber harvest, most hickory regeneration develops from advance regeneration [48]. Some advance regeneration may be mechanically damaged during logging operations, but plants typically sprout readily and many quickly overtop older residual stems. New sprouts generally grow rapidly and develop a straight bole and rapid growth. Sprouts are considered the most desirable hickory regeneration in new stands. Hickory regeneration following various types of timber harvest was as follows in an Indiana oak-hickory stand [48]. Values represent the percent of total regeneration for each harvest type:
| Regeneration type | Clearcut | Shelterwood | Medium partial |
|---|---|---|---|
| New seedlings | 2 | 2 | 2 |
| Advance reproduction | 30 | 77 | 73 |
| New sprouts | 56 | 21 | 24 |
| Stump sprouts | 12 | 0 | 1 |
Average early (fifth year) height growth of hickories was greater in clearcut (11.0 feet [3.4 m]) stands than in selection (2.0 feet [0.6 m]) or shelterwood (3.2 feet [1.0 m]) treatments.
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES10 White - red - jack pine
- FRES12 Longleaf - slash pine
- FRES13 Loblolly - shortleaf pine
- FRES14 Oak - pine
- FRES15 Oak - hickory
- FRES16 Oak - gum - cypress
- FRES18 Maple - beech - birch
BLM Physiographic Regions (Bernard and Brown 1977)
- No entry.
Kuchler Plant Associations (Kuchler 1964)
- K100 Oak - hickory forest
- K103 Mixed mesophytic forest
- K104 Appalachian oak forest
- K111 Oak - hickory - pine forest
- K112 Southern mixed forest
SAF Cover Types (Eyre 1980)
- 21 Eastern white pine
- 40 Post oak - blackjack oak
- 42 Bur oak
- 43 Bear oak
- 44 Chestnut oak
- 45 Pitch pine
- 46 Eastern redcedar
- 51 White pine - chestnut oak
- 52 White oak - black oak - northern red oak
- 53 White oak
- 55 Northern red oak
- 57 Yellow poplar
- 59 Yellow poplar - white oak - northern red oak
- 60 Beech - sugar maple
- 64 Sassafras - persimmon
- 65 Pin oak - sweet gum
- 75 Shortleaf pine
- 76 Shortleaf pine - oak
- 78 Virginia pine - oak
- 79 Virginia pine
- 80 Loblolly pine - shortleaf pine
- 81 Loblolly pine
- 82 Loblolly pine - hardwood
- 83 Longleaf pine - slash pine
- 87 Sweet gum - yellow poplar
- 88 Willow oak - water oak - diamondleaf oak
- 91 Swamp chestnut oak - cherrybark oak
- 110 Black oak
SRM Rangeland Cover Types (Shiflet 1994)
- No entry.
1. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]
2. Bonner, F. T.; Maisenhelder, L. C. 1974. Carya Nutt. hickory. 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: 269-272. [7571]
3. Boucher, Douglas H.; Sork, Victoria L. 1979. Early drop of nuts in response to insect infestation. Oikos. 33(3): 440-443. [13297]
4. Braun, E. Lucy. 1936. Forests of the Illinoian till plain of southwestern Ohio. Ecological Monographs. 6(1): 91-149. [8379]
5. Braun, E. Lucy. 1942. Forests of the Cumberland Mountains. Ecological Monographs. 12(4): 413-447. [9258]
6. Braun, E. Lucy. 1961. The woody plants of Ohio. Columbus, OH: Ohio State University Press. 362 p. [12914]
7. Burns, Paul Y.; Nichols, J. Milford. 1952. Oak pruning in the Missouri Ozarks. University of Missouri Agricultural Experiment Station Bulletin. 581(Apr): 1-8. [10156]
8. Carey, Andrew B.; Gill, John D. 1980. Firewood and wildlife. Res. Note 299. Broomall, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 5 p. [9925]
9. Daubenmire, Rexford. 1990. The Magnolia grandiflora-Quercus virginiana forest of Florida. American Midland Naturalist. 123: 331-347. [10871]
10. Duncan, Wilbur H.; Duncan, Marion B. 1987. The Smithsonian guide to seaside plants of the Gulf and Atlantic Coasts from Louisiana to Massachusetts, exclusive of lower peninsular Florida. Washington, DC: Smithsonian Institution Press. 409 p. [12906]
11. Duncan, Wilbur H.; Duncan, Marion B. 1988. Trees of the southeastern United States. Athens, GA: The University of Georgia Press. 322 p. [12764]
12. Elowe, Kenneth D.; Dodge, Wendell E. 1989. Factors affecting black bear reproductive success and cub survival. Journal of Wildlife Management. 53(4): 962-968. [10339]
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. Feldman, Thomas D. 1987. Fire control and ecological succession in McCarty Woods, Hernando County , Florida. Florida Geographer. 21: 15-19. [8689]
15. Fralish, James S. 1976. Forest site-community relationships in the Shawnee Hills region, southern Illinois. In: Fralish, James S.; Weaver, George T.; Schlesinger, Richard C., eds. Central hardwood forest conference: Proceedings of a meeting; 1976 October 17-19; Carbondale, IL. Carbondale, IL: Southern Illinois University: 65-87. [3813]
16. 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]
17. Godfrey, Robert K. 1988. Trees, shrubs, and woody vines of northern Florida and adjacent Georgia and Alabama. Athens, GA: The University of Georgia Press. 734 p. [10239]
18. Golden, Michael S. 1976. Oak-hickory components of upland forests of the Alabama Piedmont. In: Fralish, James S.; Weaver, George T.; Schlesinger, Richard C., eds. Central hardwood forest conference: Proceedings of a meeting; 1976 October 17-19; Carbondale, IL. Carbondale, IL: Southern Illinois University: 31-43. [3811]
19. Golden, Michael S. 1979. Forest vegetation of the lower Alabama Piedmont. Ecology. 60(4): 770-782. [9643]
20. Graney, David L. 1990. Carya ovata (Mill.) K. Koch shagbark hickory. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 2. Hardwoods. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 219-225. [13976]
21. Hammitt, William E.; Barnes, Burton V. 1989. Composition and structure of an old-growth oak-hickory forest in southern Michigan over 20 years. In: Rink, George; Budelsky, Carl A., eds. Proceedings, 7th central hardwood conference; 1989 March 5-8; Carbondale, IL. Gen. Tech. Rep. NC-132. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station: 247-253. [9386]
22. Hardt, Richard A.; Forman, Richard T. T. 1989. Boundary form effects on woody colonization of reclaimed surface mines. Ecology. 70(5): 1252-1260. [9470]
23. Harmon, Mark E. 1984. Survival of trees after low-intensity surface fires in Great Smoky Mountains National Park. Ecology. 65(3): 796-802. [10997]
24. Hosie, R. C. 1969. Native trees of Canada. 7th ed. Ottawa, ON: Canadian Forestry Service, Department of Fisheries and Forestry. 380 p. [3375]
25. Kartesz, John T.; Kartesz, Rosemarie. 1980. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Volume II: The biota of North America. Chapel Hill, NC: The University of North Carolina Press; in confederation with Anne H. Lindsey and C. Richie Bell, North Carolina Botanical Garden. 500 p. [6954]
26. Kaufert, F. H. 1933. Fire and decay injury in the Southern bottomland hardwoods. Journal of Forestry. 31: 64-67. [2694]
27. Krochmal, Arnold; Krochmal, Connie. 1982. Uncultivated nuts of the United States. Agriculture Information Bulletin 450. Washington, DC: U.S. Department of Agriculture, Forest Service. 89 p. [1377]
28. Kucera, Clair L. 1952. An ecological study of a hardwood forest area in central Iowa. Ecological Monographs. 22(4): 283-299. [254]
29. 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]
30. Kurz, Herman. 1944. Secondary forest succession in the Tallahassee Red Hills. Proceedings, Florida Academy of Science. 7(1): 59-100. [10799]
31. Lewis, Allen R. 1982. Selection of nuts by gray squirrels and optimal foraging theory. American Midland Naturalist. 107: 250-257. [8391]
32. 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]
33. Loeb, Susan C.; Lennartz, Michael R. 1989. The fox squirrel (Sciurus niger) in Southeastern pine-hardwood forests. In: Waldrop, Thomas A., ed. Proceedings of pine-hardwood mixtures: a symposium on management and ecology of the type; 1989 April 18-19; Atlanta, GA. Gen. Tech. Rep. SE-58. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 142-148. [10271]
34. Loomis, Robert M. 1973. Estimating fire-caused mortality and injury in oak-hickory forests. Res. Pap. NC-94. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 6 p. [8740]
35. Loomis, Robert M. 1977. Wildfire effects on an oak-hickory forest in southeast Missouri. Res. Note NC-219. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 4 p. [8738]
36. 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]
37. Martin, Alexander C.; Zim, Herbert S.; Nelson, Arnold L. 1951. American wildlife and plants. New York: McGraw-Hill Book Company, Inc. 500 p. [4021]
38. Miller, James H. 1990. Streamline basal application of herbicide for small-stem hardwood control. Southern Journal of Applied Forestry. 14(4): 161-165. [13538]
39. Miller, James H. 1990. Directed foliar sprays of forestry herbicides for loblolly pine release. Southern Journal of Applied Forestry. 14(4): 199-206. [13824]
40. Monk, Carl D. 1968. Successional and environmental relationships of the forest vegetation of north central Florida. American Midland Naturalist. 79(2): 441-457. [10847]
41. Ontario Department of Lands and Forests. 1953. Forest tree planting. 2d ed. Bull. No. R 1. Toronto, Canada: Ontario Department of Lands and Forests, Division of Reforestation. 68 p. [12130]
42. Quarterman, Elsie. 1950. Major plant communities of Tennessee cedar glades. Ecology. 31: 234-254. [11129]
43. Quarterman, Elsie; Keever, Catherine. 1962. Southern mixed hardwood forest: climax in the southeastern coastal plain, U.S.A. Ecological Monographs. 32: 167-185. [10801]
44. Quarterman, Elsie; Turner, Barbara Holman; Hemmerly, Thomas E. 1972. Analysis of virgin mixed mesophytic forests in Savage Gulf, Tennessee. Bulletin of the Torrey Botanical Club. 99(5): 228-232. [11128]
45. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. [7606]
46. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843]
47. Raup, Hugh M. 1940. Old field forests of southeastern New England. Journal of the Arnold Arboretum. 21: 266-273. [12135]
48. Sander, Ivan L.; Clark, F. Bryan. 1971. Reproduction of upland hardwood forests in the Central States. Agric. Handb. 405. Washington, DC: U.S. Department of Agriculture, Forest Service. 25 p. [273]
49. Seymour, Frank Conkling. 1982. The flora of New England. 2d ed. Phytologia Memoirs 5. Plainfield, NJ: Harold N. Moldenke and Alma L. Moldenke. 611 p. [7604]
50. Simpson, Benny J. 1988. A field guide to Texas trees. Austin, TX: Texas Monthly Press. 372 p. [11708]
51. Smalley, Glendon W. 1990. Carya glabra (Mill.) Sweet pignut hickory. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Vol. 2. Hardwoods. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 198-204. [13961]
52. 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]
53. Veno, Patricia Ann. 1976. Successional relationships of five Florida plant communities. Ecology. 57: 498-508. [9659]
54. Vines, Robert A. 1960. Trees, shrubs, and woody vines of the Southwest. Austin, TX: University of Texas Press. 1104 p. [7707]
55. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472]
56. Ward, Jeffrey S.; Stephens, George R. 1989. Long-term effects of a 1932 surface fire on stand structure in a Connecticut mixed hardwood forest. In: Rink, George; Budelsky, Carl A., eds. Proceedings, 7th central hardwood conference; 1989 March 5-8; Carbondale, IL. Gen. Tech. Rep. NC-132. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station: 267-273. [9389]
57. Webb, Sara L. 1986. Potential role of passenger pigeons and other vertebrates in the rapid Holocene migrations of nut trees. Quaternary Research. 26: 367-375. [11982]
58. Whittaker, R. H. 1954. The ecology of serpentine soils: IV. The vegetational response to serpentine soils. Ecology. 35(2): 275-288. [10397]
59. Whittaker, R. H. 1956. Vegetation of the Great Smoky Mountains. Ecological Monographs. 26(1): 1-79. [11108]
60. Wofford, B. Eugene. 1989. Guide to the vascular plants of the Blue Ridge. Athens, GA: The University of Georgia Press. 384 p. [12908]