Pinus taeda L.

Range and Habitat

The native range of loblolly pine. (From Little, 1971.)

Geographic Range


Pinus taeda is found in 14 states, mostly in the southeastern U.S. It ranges from New Jersey south to central Florida and west to eastern Texas and Oklahoma. This tree occurs in the Atlantic Coastal Plain, the Piedmont Plateau, and the southern extremities of the Cumberland Plateau and Appalachian Highlands. Loblolly, however, does not grow naturally in the Mississippi River flood plain. Because of its ability to grow quickly on a variety of sites, loblolly is extensively platned in other parts of the world for timber and pulp.

This tree grows best in moist sites, but it can grow in drier areas and compete with other pines. For example, although longleaf pine (Pinus palustris) originally dominated the Atlantic Coastal Plain before the European settlers arrived, two factors helped establish the dominance of Pinus taeda in this area. First, eroded abandoned farm fields were quickly colonized by loblolly, an aggressive pioneer on disturbed land; thus the name "oldfield pine." Secondly, fire exclusion helped loblolly pines to regenerate in areas where longleaf, a tree highly adapted to frequent fire, was dominant. Without fire, loblolly thrived and outcompeted longleaf pines.

Climate


The loblolly pine range includes a warm-temperate, humid climate. The summers are long and hot, while the winters are short, and fairly mild. Mean temperatures range from 13° to 24° C (55° to 75° F). Average July temperature is about 27° C (80° F) and average January temperature ranges from 4° to 16° C (40° to 60° F). Average yearly rainfall is between 1020 to 1520 mm (40 to 60 in).

The frost-free period ranges from 5 months in the northern areas to 10 months in the southern states. Colder winter temperatures may limit the growth of loblolly in the north, while lack of precipitation during the growing season inhibits its occurrence in the west.

Soils and Topography


The term "loblolly" literally means "mudhole" which can be used to describe the wet soil conditions on which this tree occurs naturally. Their best growth is on moderately acid soils in areas of poor surface drainage which consists of a thick, medium-textured surface layer and fine-textured subsoil. They do not grow well, however, on very wet or water-logged sites, or in areas with shallow or eroded soils.

Loblolly is mostly found on Ultisol soils, although small areas of Entisols, Spodosols, and Alfisols are scattered throughout its range. Productivity is sensitive to soil fertility; if poorly drained soils have low fertility, usually there is a decrease in productivity. Also, the presence of a spodic horizon along the root zone causes a decline in productivity. This tree is planted on Histosols following artificial drainage and site preparation.

Pinus taeda can be found on a variety of topographies, ranging from the flat Coastal Plain, to rolling Piedmont hills, to fringes of the Interior Highlands.

Forest Associates


According to Baker and Langdon (1990): "Loblolly pine is found in pure stands and in mixtures with other pines or hardwoods, and in association with a great variety of lesser vegetation. When loblolly pine predominates, it forms the forest cover type Loblolly Pine (Society of American Foresters Type 81). Within their natural ranges, longleaf, shortleaf, and Virginia pine (Pinus palustris, P. echinata, and P. virginiana), southern red, white, post, and blackjack oak (Quercus falcata, Q. alba, Q. stellata, and Q. marilandica), sassafras (Sassafras albidum), and persimmon (Diospyros virginiana) are frequent associates on well-drained sites. Pond pine (Pinus serotina), spruce pine (P. glabra), blackgum (Nyssa sylvatica), red maple (Acer rubrum), and water oak (Quercus nigra), willow oak (Q. phellos), cherrybark oak (Q. falcata var. pagodifolia) are common associates on moderately to poorly drained sites. In the southern part of its range, loblolly frequently is found with slash pine (Pinus elliottii) and laurel oak (Quercus laurifolia).

"In fertile, well-drained coves and along stream bottoms, especially in the eastern part of the range, yellow-poplar (Liriodendron tulipifera), American beech (Fagus grandifolia), and white and Carolina ash (Fraxinus americana and F. caroliniana) are often found in the Loblolly Pine-Shortleaf Pine cover type.

"Loblolly pine also grows in mixture with hardwoods throughout its range in Loblolly Pine-Hardwood (Type 82). On moist to wet sites this type often contains such broadleaf evergreens as sweetbay (Magnolia virginiana), southern magnolia (M. grandiflora), and redbay (Persea borbonia), along with swamp tupelo (Nyssa aquatica), red maple, sweetgum, water oak, cherrybark oak, swamp chestnut oak (Quercus mixhauxii), white ash, American elm (Ulmus americana), and water hickory (Carya aquatica). Occasionally, slash, pond, and spruce pine are present.

"There is a great variety of lesser vegetation found in association with loblolly pine. Some common understory trees and shrubs include flowering dogwood (Cornus florida), American holly (Ilex opaca), inkberry (I. glabra), yaupon (I. vomitoria), hawthorn (Crataegus spp.), southern bayberry (Myrica cerifera), pepperbush (Clethra spp.), sumac (Rhus spp.), and a number of ericaceous shrubs. Some common herbaceous species include bluestems (Andropogon spp.), panicums (Panicum spp.), sedges (Carex spp. and Cyperus spp.), and fennels (Eupatorium spp.)."

Habitat Competition


According to Baker and Langdon (1990): "Loblolly is moderately tolerant when young but becomes intolerant of shade with age. Its shade tolerance is similar to that of shortleaf and Virginia pines, less than that of most hardwoods, and more than that of slash and longleaf pines. Loblolly pine is most accurately classed as intolerant of shade.

"Succession in loblolly pine stands that originate in old fields and cutover lands exhibit a rather predictable pattern. The more tolerant hardwoods (including various species of oaks and hickories, sweetgum, blackgum, beech, magnolia, holly, and dogwood) invade the understory of loblolly pine stands and with time, gradually increase in numbers and in basal area. The hardwoods finally share dominance with each other and with loblolly pine.

"The climax forest for the lobolly pine type has been described as oak-hickory, beech-maple, magnolia-beech, and oak-hickory-pine in various parts of its range. Others view the climax forest as several possible combinations of hardwood species and loblolly pine. There is evidence that within the range of lobolly pine several different tree species could potentially occupy a given area for an indefinite period of time and that disturbance is a naturally occurring pehnomenon. If this is so, then the climax for this southern forest might best be termed the southern mixed hardwood-pine forest.

"Competition affects the growth of loblolly pine in varying degrees depending on the site, the amount and size of competing vegetation, and age of the loblolly pine stand. Across the southern region, average loss of volume production resulting from hardwood competition has been estimated at 25 percent in natural stands and 14 percent in plantations. In a North Carolina study, residual hardwoods after logging reduced cubic-volume growth by 50 percent at 20 years, and where additional small hardwoods of sprout and seedling origin were present, growth was reduced by another 20 percent by age 20.

"Loblolly pine can be regenerated and managed with any of the four recognized reproduction cutting methods and silvicultural systems. Even-aged management is most commonly used on large acreages; however, uneven-aged management with selection cutting has proved to be a successful alternative."

Hybrids


According to Baker and Langdon (1990): "The best-known southern pine hybrid is Sonderegger pine (Pinus × sondereggeri H.H. Chapm.), a cross between longleaf and loblolly pine. This natural hybrid occurs quite frequently in Louisiana and east Texas. It is conspicuous in nursery beds and plantings of longleaf pine because the hybrid gains height growth in the first year in contrast to longleaf seedlings, which do not. Natural hybrids of pond and loblolly pine have been observed in North Carolina, and those of pond, loblolly, and pitch pine have been recognized and studied in New Jersey, Delaware, and Maryland. Natural hybrids of loblolly and shortleaf are known to occur in Oklahoma and east Texas, and based on observations of tree characteristics intermediate between loblolly and shortleaf, they probably also occur in Louisiana and Arkansas in areas where the two species commonly occur together. Hybridization between these two species is thought to contribute to the fusiform-rust resistance of loblolly pine from those sources.

"Artificial hybrids of loblolly pine and the other southern yellow pines have been produced. Two crosses-loblolly × shortleaf pine and loblolly × pitch pine-show considerable promise for use on a commercial scale. The loblolly × shorleaf cross will be used in areas with high fusiform-rust incidence for breeding a strain of loblolly pine reistant to the disease. The loblolly × pitch cross has growth characteristics of loblolly pine and cold resistance of pitch pine, making the hybrid more suitable for plantings in the north."


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