Longleaf Pine 

Site Zones

Philip J. Craul, John S. Kush, and 

William D. Boyer

Longleaf Pine 

Site Zones

Philip J. Craul, John S. Kush, and 

William D. Boyer

Southern 

Research Station

General Technical

Report SRS–89

United States

Department of

Agriculture

Forest Service
The Authors

September 2005

Southern Research Station

P.O. Box 2680

Asheville, NC 28802

Phillip J. Craul, Professor of Soil Science (Emeritus), SUNY-College of 

Environmental Science and Forestry, Syracuse, NY, and Senior Lecturer in 

Landscape Architecture, Harvard University, Graduate School of Design, Manlius, 

NY 13104-9504; John S. Kush, Research Associate, Auburn University, School of 

Forestry and Wildlife Sciences, Auburn, AL 36849-5418; and William D. Boyer, 

Principal Silviculturist (retired), USDA Forest Service, Southern Research Station, 

Auburn, AL 36830.

Cover photo: Longleaf pine stand near Flomaton, AL, ca. 1963. (Formerly known as 

Hauss Park.)
i

Longleaf Pine Site Zones

Phillip J. Craul, John S. Kush, 

and William D. Boyer
ii
iii

Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Methods and Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

 Climatic Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

 Physiographic Provinces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

 Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Site Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Climatic Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Physiographic Provinces and Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

 Soil Orders and Suborders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

 The Longleaf Site Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix—Climogram of the 45 Stations Used in the Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
iv
v

FOREWORD

The senior author completed analysis and mapping for 

a longleaf pine site zones report in 1965. This work was 

done for the Longleaf Pine Silviculture Project, Escambia 

Experimental Forest, Southern Forest Experiment Station, 

Brewton, AL. With the renewed interest in longleaf pine 

restoration, increased planting efforts on abandoned 

agricultural lands, and the potential for planting longleaf 

pine for long-term carbon storage, this work on longleaf 

pine site zones can be put to practical use. For example, it 

can help foresters judge what seed sources may be planted 

safely in what locations. The interaction of climate, soils, 

and physiography when planting seed sources from one 

area in another must be considered. It is recommended that 

plantings of longleaf pine in any one of the six climatic 

areas (shown in figure 5) use a seed source from the same 

climatic area. Work by Wells and Wakeley (1970) indicated 

some consequences of planting seed from one source in 

another site zone. Their observations suggested that climatic 

zones may be the most important consideration.

It is recommended that the results of this study be incorporated in the future design and planning of longleaf site 

evaluation studies and others of a regional nature.

Because nearly 40 years have passed since the site zones 

work was completed, new data relating to climatic, physiographic, and soils factors have become available. New 

methods for analyzing climatic data are employed now and 

soils work has changed in significant ways. 

The climate of a region or a locality may be characterized as 

relatively stable if it is described on the basis of long-term 

climatological data. The time period covered by the data 

averages should be at least 30 to 50 years to mask shortterm cycles of 3, 5, or 7 to 11 years, which are typical in 

most climatological data. Longer cycles may have more or 

less effect on the averages. Also, very long trends, such as 

global climate change, can cause averages for earlier and 

later periods to differ. If one employed data for the last 30 

years from the stations used in the longleaf site zones study, 

different climograph patterns might result, modifying the 

groupings and the differentiations of the climatic zones 

made in the original study. Other time-related effects are 

the likely increase in the number of observation stations 

within the study area and improved instrumentation and 

data-gathering techniques that would refine the delineation 

of boundaries between climatic zones. Over a long period, 

the potential changes in climatic patterns and zones may 

influence the distribution of longleaf pine through their 

influence on factors such as soil moisture, fire hazard, 

reproduction, insect and disease occurrence, competition 

with other plant species, and perhaps more profoundly, land 

use changes.

In the 1960s, ecologists considered that the shapes of climographs of mean monthly temperature and mean monthly 

rainfall (see appendix) were a sound basis for differentiating 

among climatic zones. This technique is regarded with less

favor today, but the limited availability of sufficiently long

term climatological data and the limited number and location

of observation stations dictated the choice of climograph

patterns as the discriminating factor. More recent advances 

in graphical discriminant analysis would aid in the more 

precise differentiation and grouping of the climatic zones 

based on the climograph patterns, but one may wonder if the 

work would be any more accurate. 

Though climatological maps similar to those of Thornthwaite

and others (1958) were available in 1965, none of them 

contained sufficient detail at an appropriate scale to differentiate the longleaf pine region into climatic zones. The results 

of Philip Wakeley’s (1953, 1959, 1961, 1963) southwide 

seed source studies provided some evidence of the existence 

of different zones, as did some unpublished informal growth 

studies reviewed by Robert Farrar of the Brewton office. 

The soils of the longleaf pine region have not changed since 

the study was closed. Only the series names and taxonomic 

classifications have been modified, added, or eliminated. 

But here again, at the scale examined and mapped for the 

entire longleaf pine range, the delineation of units at the 

higher categories of classification (including the orders 

and suborders) should not have changed significantly. The 

classification, taxonomy, and correlation of more local soil 

delineations (of the family, series, and perhaps subgroup 

categories) have probably changed most radically. The 

family category, being defined primarily on the basis of soil 

properties that influence plant productivity, was felt to be 

the most potentially useful soil mapping unit for forestry 

purposes at the time the study was conducted. However, 

very few if any family-level maps were available. Moreover, 

some families were not yet fully defined. 
vi
1

Longleaf Pine Site Zones

Phillip J. Craul, John S. Kush, and William D. Boyer

Abstract

The authors delineate six major climatic areas of the longleaf pine (Pinus 

palustris Mill.) region. They subdivide these areas into 21 site zones, each 

of which is deemed homogenous with respect to climate, physiography, and 

soils. The site zones are mapped and their climate, physiography, and soils 

described. The authors recommend that plantings of longleaf pine in any 

of the six major climatic areas of the longleaf region be made with a seed 

source from the same area.

Keywords: Climatic zones, longleaf pine, physiographic provinces, Pinus 

palustris, site zones, soils.

INTRODUCTION

The longleaf pine (Pinus palustris Mill.) region extends 

from southeastern Virginia to east Texas. It includes several 

climatic zones, several physiographic provinces, and many 

soils. These three site factors are thought to have the most 

influence on the growth and yield of longleaf pine and other 

tree species, especially as they affect temperature regimes 

and moisture conditions under which the trees grow. It is 

reasonable to assume that these same site factors would 

affect longleaf pine regeneration and growth as well.

Site study results often are not applicable in areas outside 

the original study area. The literature on the subject shows 

that this lack of applicability is usually attributable to differences in the relationships between tree growth and environmental factors from one locality to another. It follows, then, 

that these differences in environment within the longleaf 

pine region should be identified and defined, and that environmentally homogeneous areas should be delineated. With 

this information available, site studies may be executed 

more soundly and the results interpreted more completely 

by restricting them to one area or by making observations 

in all areas. Other studies of longleaf pine problems may be 

improved as well, particularly on a regional basis.

Unfortunately, little is known of the effect of the environment on longleaf pine regeneration, development, and 

growth. However, enough information is available to indicate that some differences in environmental influences or 

effects in the longleaf region cause detectable differences in 

the growth and yield of the species. The growth and yield 

differences are sufficiently great to be of concern in the 

management of longleaf pine forests.

The objectives of this study are to (1) identify and define the

climatic, physiographic, and edaphic differences in the longleaf pine region, and (2) describe and delineate longleaf pine 

site zones (areas homogeneous with respect to significant 

environmental factors).

METHODS AND PROCEDURES

Climatic Zones

We examined climographs of average monthly mean 

temperature and precipitation for 45 stations in the longleaf 

region. These stations were selected on the basis of their 

location with respect to concentrations of longleaf growing 

stock so that the climographs would be representative of 

the climate in which the longleaf would be growing. The 

data for the climographs were obtained from the “Climatic 

Summary of the United States—Supplement for 1931 

through 1952, Series 11” for the eight Southeastern States 

(U.S. Department of Commerce Weather Bureau 1954). 

Generally, stations for which at least 20 years’ records 

were available were selected; however, in some cases only 

stations with a shorter record period could be used.

The climograph shapes or patterns were then compared for

similarities that would indicate the locations of climatic 

zones. We also consulted annual and warm season rainfall

maps (U.S. Department of Agriculture 1941) as well as 

maps of water surplus, water deficit, and potential evapotranspiration for the Eastern United States (Thornthwaite 

and others 1958). Climatic zones were delineated on the 

basis of all this information. No actual values for these 

factors were computed for any of the stations. In 1965, 

climatological research had not yet reached the point where 

fine distinction could be made quantitatively.

Physiographic Provinces

These provinces are delineated on the basis of information in Fenneman (1938), Lobeck (1948), Cooke (1945), 

and various publications of State geological surveys. The 

publications on the Southeastern physiographic habitats by 

Hodgkins (1960, 1965) were also consulted.
2

Soils

The soil areas are delineated on the basis of the “General Soil

Map of the United States” (U.S. Soil Conservation Service 

1964). This map was based on the dominant orders and 

suborders of the new soil classification system (Soil Survey 

Staff 1960) and incorporated the latest information available 

in 1965 on the new system. Due to the transitional period 

during the 1960s in soil classification in the United States, 

this site factor was discussed with elements from both the 

old and the new systems of classification that were available. 

The purpose of the present discussion is simply to define the

broad soil areas in the longleaf region. No attempt is made to

give detailed descriptions for any particular locality. This 

detail should be obtained from the various county soil survey

reports published by the U.S. Soil Conservation Service.

Site Zones

A separate map was drawn to show areas of homogeneity 

for each of the three site factors (figs. 1 through 4). A final 

map was drawn in which the zone boundaries are delineated 

by the overlapping homogeneous areas (fig. 5). Thus, areas 

that are homogeneous with respect to climate, physiography, 

and soils are shown in figure 5.

RESULTS AND DISCUSSION

The results of the analyses for the three environmental 

factors of site are discussed separately. The results are then 

compiled and discussed in terms of the several regional site 

zones.

Climatic Zones

General—The Gulf of Mexico is an important source of

moisture for air masses that invade the continent from the 

south. The presence of these moist air masses, above all else, 

influences the climate of the Southeastern States. During the 

winter the Southeast is a region of frequent frontal activity, 

and thus there are periods of onshore and offshore winds. 

Figure 1—The climatic zones of the longleaf pine region.
3

High temperatures prevail when maritime tropical air moves 

northward, while north winds produce low temperatures. 

Cold anticyclones occasionally result in an extreme southward displacement of very cold polar continental air. These 

cold waves are accompanied by temperatures well below 

freezing throughout the Southeast and Gulf States. During 

the winter, precipitation over the Gulf States arises either 

from frontal lifting or from horizontal convergence. With 

the high moisture content of maritime tropical air, heavy 

precipitation occurs quite frequently. This winter precipitation is usually connected with cyclones that develop over 

the Southern States or over the Gulf of Mexico. The summer 

precipitation is almost entirely of convective origin—afternoon showers and thundershowers are common, especially 

inland from the gulf coast. This convective rainfall results in 

a summer precipitation maximum.

Consistently with the frequent precipitation, the mean 

cloudiness is high in comparison with that of the western 

plains. With the cooling of maritime tropical air as it moves 

northward, light fog and low stratus clouds are sometimes 

observed during the colder months. Similarly, poor visibility 

conditions occur during periods of continuous light warmfront precipitation.

The climate of eastern Texas resembles that of the other 

Gulf States. Over the South Atlantic States, frequent invasions of maritime tropical air ahead of an eastward moving 

cyclone result in periods of high temperatures. Florida, 

because of its insular characteristics, has a relatively high 

mean winter temperature.

Climate is influenced and modified by geography and 

topography. Therefore, geography and topography must be 

considered and discussed in connection with climatic zones.

Climate of the Lowlands of North and South Carolina—

The climate of this area is characterized by that of 

Goldsboro, Lumberton, and Wilmington, NC; and by that of 

Conway, Kingstree, and Yemassee, SC (fig. 1 and appendix). 

With two exceptions, these locations have a precipitation minimum in October. Yemassee, SC, has a January 

minimum and Wilmington, NC, has a November minimum. 

The maximum occurs in July except in southeast South 

Figure 2—The physiographic provinces of the longleaf pine region after Lobeck (1948).
4

Carolina; there late summer tropical storms follow the coast 

and contribute to an August maximum. The mean annual 

rainfall ranges from 44.46 inches at Kingstree, SC to 50.01 

at Conway, SC. All stations, except Goldsboro, NC, exhibit 

a July temperature maximum and a December minimum; 

Goldsboro, NC, has a January minimum. The warming cycle 

is more gradual than the cooling cycle. The annual mean 

temperature ranges from 62.7 °F at Goldsboro, NC, to 65.8 

°F at Yemassee, SC. This section of the coastal lowlands is 

cooler and drier than areas farther to the south. It is warmer 

and more moist than the section farther inland (west).

Climate of the Sandhills of North Carolina and South 

Carolina—This discussion applies to the true Sandhills 

and also an area lying west and inland from the Lowlands. 

The area’s climate is characterized by that of Pinehurst 

and Fayetteville, NC; and Cheraw, Darlington, and Aiken, 

SC. The mean annual rainfall ranges from 42.96 inches 

at Darlington, SC, to 49.44 inches at Pinehurst, NC. All 

stations have an October rainfall minimum except Pinehurst, 

NC, which has a November minimum. The maximum occurs 

in July and August. The average annual mean temperature 

ranges from 61.5 °F at Pinehurst, NC, to 63.7 °F at Aiken, 

SC. The maximum monthly mean temperatures occur in 

July at all stations, and the minimum monthly mean occurs 

in January, rather than in December as on the Lowlands. The 

southern boundary of this zone, approximately the South 

Carolina–Georgia border, follows the 39.27 inches potential 

evapotranspiration line of Thornthwaite and others (1958). 

The inland west boundary is the Piedmont Plateau physiographic province.

Climate of the Uplands of Georgia—This section includes 

a portion of northwest Florida and southeast Alabama. It 

lies southwest of the previous section and differs from it in 

having higher annual mean temperatures and two rainfall 

peaks (February or March and July) rather than just one. 

The stations whose climates typify this climate are Millen, 

Eastman, Tifton, and Bainbridge, GA; Geneva, AL; and 

Tallahassee, FL. The latter two stations are transitional 

between this section and the Florida section. The annual 

mean temperature ranges from 66.5 °F at Millen, GA, to 

67.6 °F at Bainbridge, GA. The maximum monthly mean 

temperature occurs in July and the minimum in December. 

Figure 3—The physiographic provinces of the longleaf pine region after Fenneman (1938).
5

The average annual rainfall ranges from 44.33 inches 

at Millen, GA, to 56.77 inches at Tallahassee, FL. This 

section comes under the influence of both Atlantic and 

Gulf storms at various times but does not receive the high 

amount of precipitation that occurs farther south or to the 

west in Alabama. The rainfall maximum occurs in July, and 

the minimum occurs in October except at Eastman, GA, 

where it is in November. This section is also characterized 

by greater divergence between the rainfall patterns of the 

warming and cooling cycles than in the sections discussed 

previously.

Climate of the Florida and the Georgia Lowlands—The 

boundary of this section extends along the coastal lowlands 

of Georgia and a very small portion of extreme southeastern 

South Carolina, southward across north-central Florida, 

and westward to the Gulf southwest of Tallahassee. The 

climate of this section is characterized by that of the stations 

located at Waycross and Brunswick, GA, and Lake City, 

Gainesville, Eustis, and Avon Park, FL. The Avon Park 

station is located at the southernmost limit of the longleaf region in peninsular Florida and also coincides with 

Thornthwaite’s 44.88 inches potential evapotranspiration 

line. The average annual rainfall ranges from 47.68 inches 

at Waycross, GA, to 53.51 inches at Avon Park, FL. The 

annual mean temperature ranges from 68.6 °F at Waycross, 

GA, to 73.7 °F at Eustis, FL. The stations in this section 

exhibit the patterns of maritime tropical climate with mild 

temperatures and high rainfall. Maximum monthly rainfall 

occurs in July in Florida but in September at Brunswick, 

GA. Minimum monthly rainfall occurs in November. The 

maximum monthly mean temperature occurs in August 

and the minimum monthly mean occurs in January. These 

extremes occur 1 month later here than in the Uplands of 

Georgia.

Climate of the Alabama-Mississippi middle Coastal 

Plain—This section includes the area of northwest 

Florida surrounding Pensacola, FL, southern Alabama 

and Mississippi, and the Florida Parishes of northeastern 

Figure 4—Soil orders and suborders of the Southeastern United States, after the Seventh Approximation.
6

Louisiana. It lies to the west of the Georgia Uplands. The 

stations whose climates characterize the climate of this 

section are Brewton and Greenville, AL; Pensacola, FL; 

Shubuta, Columbia, Hattiesburg, and Poplarville, MS; and 

Amite and Bogalusa, LA. This section generally comprises 

what is sometimes considered the East Gulf Coast. A small 

distinct climatic area located east and north of Mobile Bay is 

not included in the present section. It will be discussed separately. The average annual rainfall ranges from 58.63 inches 

at Shubuta, MS, to 63.19 inches at Poplarville, MS. The 

rainfall patterns are quite similar for all stations and exhibit 

two distinct and nearly equal maximum monthly peaks in 

March and July. A third, but much smaller, peak occurs in 

December. The rainfall minimum occurs in October at all 

stations, and a secondary low occurs in May at most stations 

and in June at Shubuta and Hattiesburg, MS, and Bogalusa, 

LA. The maximum monthly mean temperature generally 

occurs in August but occurs in July at several stations. The 

minimum monthly mean temperature occurs in January at 

all stations. A characteristic that distinguishes this section 

from the Georgia uplands is the even greater divergence 

of the rainfall pattern between the warming and cooling 

cycles. The average annual mean temperature ranges from 

65.6 °F at Shubuta, MS, to 68.0 °F at Pensacola, FL. Hence, 

the temperature regime in this section is much like that in 

the Georgia uplands, but it gets more rainfall. This section 

differs from the Florida section by having two rainfall peaks, 

rather than just one in July. This section generally coincides 

with Thornthwaite’s 20-inch annual water surplus area, and 

this surplus is the greatest in the whole longleaf belt and the 

eight Southeastern States included in this study.

Climate of the Bay Insert—This section indents the 

Alabama-Mississippi section to the east and north of Mobile 

Bay. The Bay Insert’s climate is characterized by that of the 

stations located at Robertsdale, Bay Minette, and Citronelle, 

AL. The Mobile Bay exerts an impressive influence on the 

climatic patterns of the section. The major differentiating 

characteristic of the insert is its high average annual rainfall, 

which ranges from 65.70 inches at Citronelle, AL, to 69.24 

inches at Robertsdale, AL. Otherwise, the Bay Insert’s rainfall pattern is very similar to that of the Alabama-Mississippi

Figure 5—The climatic areas and site zones of the longleaf pine region.
7

Climate Summary—Several climatic zones within the 

longleaf pine region may be recognized. Annual rainfall and 

mean temperatures increase as one proceeds south along the 

Atlantic coast to Florida and Georgia, and rainfall continues 

to increase to the west into northwest Florida, southern 

Alabama, and Mississippi. Annual mean temperatures 

increase slightly in the latter area, and winter temperatures 

are milder there than elsewhere except Florida. Rainfall 

reaches a high maximum at Mobile Bay. Generally, the 

inland Coastal Plain areas of the longleaf region have lower 

rainfall and higher mean temperatures than the seaward 

areas. The mountain portion of the longleaf pine range has 

a climatic pattern unlike any of the others within the region. 

The area that lies in Louisiana and east Texas has climatic 

characteristics that approach those of the moisture-tension 

zone of the Midwest.

Physiographic Provinces and Sections

General—The longleaf pine region occurs predominantly 

on the Coastal Plains of Southeastern United States, and 

for most purposes might be considered as being restricted 

to them. As figure 2 (Lobeck 1948) shows, the Coastal 

Plains are further subdivided into the upper, middle, and 

lower Coastal Plains. These are easily distinguishable topographically and to a lesser extent geologically. The Plains 

are approximately parallel to the Atlantic and Gulf coasts, 

turning inward and northward in the Mississippi Valley. 

The peninsula of Florida is generally considered as being 

entirely in the lower Coastal Plain province. The landward 

boundary of the Coastal Plain provinces is the Piedmont 

Plateau province except in northern Alabama where they 

border the southern ends of the Great Valley, Valley and 

Ridge, and Cumberland Plateau provinces.

The Coastal Plain consists of loose or only partly consolidated formations of sand, gravel, clay, or marl, in many 

places indurated by an appreciable amount of iron oxide or 

limonite. The slope of this newly emerged surface is very 

slight, being only 2 to 4 feet to the mile. Because of the 

gradual uplift of the Coastal Plain and the resulting greater 

erosion of its inner margin, the older or underlying beds 

are exposed there in varying amounts. The Coastal Plain 

exhibits a series of belts roughly parallel with the coast 

(fig. 3) (Fenneman 1938). The youngest formations are 

adjacent to the shore whereas older and older beds appear 

inland, the ages of these formations ranging from presentday and recent Pleistocene sands and clays to Tertiary and 

Cretaceous beds of similar types.

The several belts of the Coastal Plain vary not only in the 

geological age of the formation, and in the kind of material

middle Coastal Plain. Whether or not this increase in annual 

rainfall is sufficient to cause a significant difference in longleaf growth remains to be seen. 

Climate of the Alabama mountains—Longleaf pine occurs

in northern Alabama as a disjunct, separated from the middle

and lower Coastal Plains longleaf by the Black Belt physiographic province. The climate of this section is characterized by that of the stations located at Anniston, Talladega, 

and Centreville, AL. The first two stations are located in the 

extreme southern end of the Blue Ridge Mountains, in eastcentral Alabama, while that last is located on the Fall Line 

Sandhills or upper Coastal Plain in west-central Alabama. 

This section might possibly be further divided on the basis 

of climate alone. Anniston and Talladega, AL, have lower 

annual mean temperatures than Centreville, AL (62.5 °F 

and 63.6 °F vs. 64.5 °F). The difference in rainfall is even 

greater (52.20 and 52.52 vs. 57.22 inches). The climate 

in the Alabama mountains division is completely unlike 

that of any other portion or section of the longleaf region. 

Physiography will probably have greater influence on microclimate in this section than elsewhere in the region.

Climate of the Louisiana-east Texas Coastal Plains—This 

area of longleaf pine is separated from the remainder of the 

region by the Mississippi River Valley and Delta. It is more 

extensive than the section in northern Alabama. Its climate 

is characterized by those of Urania, Cheneyville, and Ville 

Platte, LA; and Nacogdoches, Huntsville, and Kirbyville, 

TX. On the basis of average annual rainfall, the section 

could be divided into two parts, the state line forming the 

boundary. Rainfall at the three stations in Louisiana is 59.13, 

62.79, and 59.03 inches per year. Rainfall at the Texas 

stations is 47.89, 46.58, and 54.14 inches per year. Thus, a 

10-inch annual rainfall difference splits this area into two 

sections. At the stations in Louisiana, the maximum monthly 

rainfall occurs in January or December with a second peak 

in March and a third in July. The minimum monthly rainfall 

occurs in October with a secondary low in June at Urania, 

LA, and in February at Cheneyville and Ville Platte, LA. A 

third low occurs in April at Ville Platte, LA, and in February 

at Urania, LA. The temperature patterns for Louisiana and 

Texas are similar. The maximum monthly mean temperature occurs in August and the minimum in January. The 

maximum monthly rainfall occurs in December at Kirbyville 

and Nacogdoches, TX, and in November at Huntsville, TX. 

Secondary peaks occur in May and July at Kirbyville, TX, 

and in January and May at Huntsville, TX. At Nacogdoches, 

TX, secondary peaks occur in May and July. The 4-inch 

annual water deficit line of Thornthwaite and others (1958) 

follows the Louisiana-Texas border through this section.
8

of which they are composed, but also in their topographic

relationship. The innermost belt that developed on Cretaceous

clays is usually a lowland, whose inner margin is the fall 

line or fall zone. In the Carolinas and Georgia the Coastal 

Plain is quite wide. Here the lowland and its adjacent cuesta 

form a parallel series of plains and dissected uplands called 

the Fall Line Hills. The other sections of the Coastal Plain 

have their own distinguishing characteristics. 

Throughout its entire extent the seaward margin of the 

Coastal Plain is fringed with a strip of offshore bars behind 

which is a more or less continuous lagoon or belt of marshes 

and ponds.

Figures 2 and 3 (Fenneman 1938, Lobeck 1948) indicate

that the physiography of the longleaf pine region may be 

described simply or in detail depending on the intended 

purposes. Since it will later be seen that some of the same 

soils occur in several of the physiographic sections of 

the region, detailed differentiation of the several sections 

as illustrated in figure 3 (Fenneman 1938) may not be 

necessary for defining homogeneous areas. However, it is 

proposed to describe these sections in detail because they 

are generally well distinguished in the field, and future work 

in site evaluation may require their differentiation. 

Fall Line Hills or Sandhills section—The Cretaceous 

formations that outcrop and appear in these hills are mainly 

sand (occasionally cemented) with only minor beds of 

clay. They are not overlain by a clay formation as in central 

Alabama (the Black Belt). There are, therefore, no lowlands 

at the inner edge of the province in the Carolinas and Georgia.

This hill belt is more eroded than the plain farther out 

because it is higher (crests 500 to 600 feet) and has been 

exposed longer to erosion.

The belt is 20 to 40 miles wide over most of its extent and 

reaches a maximum width of 50 miles in western Alabama 

and eastern Mississippi. The half next to the Piedmont or the 

inner edge is on the Cretaceous outcrop. It has barren yellow 

sandy soil (Lakeland and Norfolk, etc.) and has little or no 

flatland remaining at the summit level. In Alabama, altitudes reach more than 700 feet and decline southward to the 

Black Belt. This is sometimes called the Central Pine Belt 

of Alabama. An exceptional cuesta near the middle of the 

belt in Alabama contains some areas of rugged wilderness. 

The underlying rocks of this zone are from the Tuscaloosa 

formation. Farther out, the rocks are from the Eutaw formation, and these hills are covered with a bright red residual 

sand or loam, which is very fertile. The name Red Hills is 

used to designate them. The Red Hills are sparse north of 

the Santee River, in the middle of South Carolina.

Brandywine Terrace—This terrace occurs in Virginia (and 

northward), the Carolinas, and Georgia, and lies outward or 

seaward from the Fall Line Hills. In Georgia, it is separated 

from the Fall Line Hills by the Tifton Upland.

Most of the gravel once called “Lafayette” lies beneath the 

terrace and constitutes some remarkable smooth, seaward 

sloping plains. The preservation of these is enhanced by 

the porous character of the material, which favors percolation and thus hinders erosion. These flats grade into mild 

undulations and, near streams, into hills of steeper slope. In 

southern Virginia and North Carolina the terrace lies only 

in part on these Tertiary gravels. Locally it truncates older 

formations among which are Eocene rocks that give rise 

to the Red Hills. Under such conditions the Brandywine is 

much eroded, the underlying materials being more readily 

washed than the Lafayette gravels.

Tifton Upland—This area intervenes between the Red 

Hills and the Brandywine terrace in Georgia, and forms a 

strip 30 to 50 miles wide. Geologically, it is distinguished 

from the Red Hills (Louisville Plateau in Georgia) by a 

Miocene cover (Altamaha Grit), the weathering of which 

has produced a gray or yellowish sandy soil (Tifton-Norfolk 

association) clearly distinguished from the red soil on the 

Eocene. As a result of weak rocks and submature dissection it is a district of gently rolling hills with broad rounded 

summits, having generally < 50 feet relief and never more 

than 100 feet except near the larger streams that cross in 

wide, flat-bottomed valleys several hundred feet deep.

Both the Brandywine and Coharie Terraces are somewhat 

eroded, and it is difficult to distinguish the two terraces from 

the Tifton Upland except in elevation. Large flat expanses 

occur, and the Coharie even bears some extensive swamps 

or bays. The terraces also resemble the Tifton Upland in that 

they are covered by a sandy soil that supports longleaf pine 

and wiregrass.

Coharie and Sunderland Terraces—At an altitude of 

about 215 feet, another level appears prominently in North 

Carolina. This is the Coharie Terrace. It is succeeded in turn, 

either gradually or abruptly, by the Sunderland Terrace at 

170 feet or less. The Sunderland Terrace appears as a continuously flat landscape, but tributary streams leave no large 

part of it untouched by erosion. The level of the Sunderland 

Terrace declines seaward, locally, to the 100-foot contour 

line without a break before it gives way to the Wicomico, 

whose maximum height is at that level. In North Carolina 

the Sunderland Terrace is cut off by the Surry escarpment, 

at which the level may drop abruptly 30 feet or more to the 

Wicomico or even the Penholoway level. The Sunderland 
9

Terrace separates what is popularly called the “uplands” 

from the “lowlands.” The Sunderland and Coharie Terraces 

form a broken line or belt through Virginia and North 

Carolina, and much of the area is underlain by late Tertiary 

gravel not easily distinguished from that which may have 

been deposited by the waters of the sea that cut the terrace. 

As one descends from the Coharie Terrace to the Sunderland 

in southeastern Georgia, erosion topography is almost left 

behind. This terrace is flattest in this State and extends into 

northern Florida, south of the Okefenokee Swamp. It then 

rises again to the so-called Central Highlands of peninsular 

Florida. This large area is highly diversified. It includes 

high swampy plains, the highest in the State, and thousands 

of lakes. The soils are predominantly sandy. Much of the 

sand was derived from the Pleistocene marine terraces, a 

good deal from the Miocene Hawthorn formation and the 

Pliocene Citronelle formation. The altitude ranges from 

about 40 feet above sea level in the valleys to 325 feet on

the summit of Iron Mountain near Lake Wales, FL. Relief 

here is due more largely to solution than any other agency. 

Some scattered hills of gentle slope seem to represent the 

failure of Pleistocene sediments to obscure older inequalities. Solution is favored by the porous sandy mantle that 

prevents rain water from running off, retaining it for the 

slower processes of percolation, descent, and solution. 

Streams are relatively few.

Wicomico, Talbot, and Pamlico Terraces—These terraces 

constitute what are commonly called the “lowlands” or 

“flatwoods” of the coastal Carolinas, Georgia, and Florida. 

They are widest in North Carolina, narrowing through South 

Carolina, Georgia, and northern Florida. They again become 

wide in southern Florida where they make up that entire 

section of the State. The terraces continue northward on the 

west coast of the peninsula and thence westward. 

The terraces are difficult to distinguish in the field because 

they are all unaffected by erosion, giving rise to broad, flat 

areas of poorly drained lands consisting of swamps, bogs, 

bays, and marshes. Topographic maps are the best means 

to distinguish them. Cooke (1945) gives the following 

altitudes:

 Wicomico Terrace 100 feet above mean sea level 

 (MSL)

 Penholoway Terrace 70 feet above MSL

 Talbot Terrace 42 feet above MSL

 Pamlico Terrace 25 feet above MSL

The Dougherty Plain—An upland of a different character reaches from the southeastern corner of Alabama into 

Florida and spreads widely into southern Georgia. This 

upland, the Dougherty Plain, is derived from the limestones of the Hatchetigbee Anticline of western Alabama 

and eastern Mississippi. It is nearly flat, having shallow 

flat-bottomed or round depressions made by solution. The 

lime-sink district of Florida has the same character. From 

the Conecuh River in Alabama to the Flint River in Georgia 

this limestone plain has the form of a low cuesta. Generally, 

the inner edge is 400 to 500 feet above the sea. West of 

the Chattahoochee River the plain slopes southward into 

western Florida, to the edge of the Southern Pine Hills. 

Active solution in the plain has transferred most of the 

drainage from the surface to underground channels.

The Southern Pine Hills—The broad area is cuesta-like, 

with its north-facing scarp, beginning near Vicksburg, 

passing south of Jackson and on into central Alabama. It 

is held up mainly by the sandy or gravelly, porous, and 

therefore not easily erodible, Citronelle (Pliocene) formation. Generally, this rests on the Catahoula (Miocene) 

sandstone whose importance as a scarp maker increases 

westward and decreases eastward as its character gradually 

changes and it becomes the Tampa limestone. Resistance 

to erosion is aided by actual induration, some of the sandstone being quartzitic, though it is still due mainly to the 

porous character of the beds. The belt of Southern Pine 

Hills slopes southward from an altitude of 400 or 500 feet 

to the limit of the Pleistocene coastal terraces, or about 100 

feet. Dissection at the north is generally mature or nearly 

so. Uncut uplands become broader towards the southern 

margin, but even here the surface is sufficiently dissected 

that the limit of the young Pleistocene formations might be 

drawn fairly well by contrast in topography. The red, orange, 

and yellow residual loam, which covers the Hills belt, is 

characteristic of the Citronelle formation. These soils form 

what is generally considered the Norfolk-Ruston-Tifton 

association. The Tifton Upland is the eastern continuation of 

the Southern Pine Hills, being the same physiographically, 

although its surface beds are not quite the same geologically. 

This belt is continuous across northern Florida, extending 

east into the Carolinas (Brandywine and Coharie Terraces), 

and westward into Texas where it is known as the Kisatchie 

Terrace. Throughout its extent it has the characteristic sandy 

soil and the same abundance of longleaf pine.

The Citronelle formation is predominantly sandy but 

contains lenses of clay. The sands are cross-bedded and 

generally red; the clays vary in color according to the 

extent to which they are weathered and are mottled gray 

and purple, red, or yellow. Clay pebbles or pellets are not 
10

uncommon. Extensive gravel deposits are found in the 

formation. The thickness of the Citronelle ranges from a thin 

veneer to 340 feet in southern Alabama.

The Citronelle formation is widely distributed as outliers 

or as a veneer over older formations (Adams and others 

1926). It forms a large part of what was originally called the 

Lafayette formation, but excludes certain outlying deposits 

of the Lafayette which are not considered to be river terraces 

or weathered material derived from several underlying 

formations.

The original surface of the formation formed a series of 

plains that slope gently toward the gulf, but it has been so 

altered by erosion that only a few remnants remain in some 

locations. The present topography is rolling to hilly and the 

maximum range of relief is over 450 feet.

The Pine Meadows—Between the Southern Pine Hills 

and the sea in southern Mississippi and southwest Alabama 

is a strip of coastal lowlands generally < 20 miles wide 

and narrowing almost to zero width at Mobile Bay. These 

lowlands are known as the Pine Meadows and are more or 

less the continuation of the “lowland” terrace of Florida 

(Wicomico, etc.). The Pine Meadows generally give way 

to the Southern Pine Hills at a height of not over 100 feet. 

The landscape is one of faint relief, but low seaward-facing 

scarps are discernible. The thin covering of Pleistocene sediments is insufficient to obscure completely the older sinkholes or to prevent new ones from forming. 

The Nacogdoches Cuesta and Terrace—This physiographic

section is located in east Texas. North of the Colorado River

it is a well developed cuesta, although both slopes are carved

by streams. The lower part of the dip slope covers 10 to 25

miles of clays worn down to a gently undulating surface whose

fertile soil contrasts with that of the higher zone. This broad 

ridge owes its existence mainly to the iron content of the 

underlying sediments, which are largely marl and greensand. 

Concentration of iron in certain beds which now cap the hills

explains their resistance to erosion. Some of the iron is sufficiently concentrated to be used as ore. Iron in the soils also

explains the bright prevalent colors of yellow, red, and orange.

The entire cuesta north of the Brazos River has a maximum 

width of 75 miles. Both the rougher marl zone and the 

smoother clay zone continue south of the Brazos. The rocks 

that make the Nacogdoches Cuesta are widely exposed in 

northern Louisiana and southern Arkansas, but the distinctive form is lost there in a broad expanse of low rolling hills. 

The Kisatchie Terrace—This terrace has already been 

described as the western extension of the Southern Pine 

Hills that is underlain by the Catahoula and Citronelle 

formations. This is the most prominent relief feature in 

Louisiana where it reaches maximum development. It is a 

line of high rugged hills (cuesta) on the north, leveling out to 

the south into broad gravel-covered flats. Some of the flats 

extend for 20 to 30 miles, though not without dissection. 

These represent a once extensive alluvial cover, remnants of 

the Citronelle. 

The Pine Flats—In east Texas a seaward-facing scarp 

separates the flats of the Kisatchie Terrace from the almost 

featureless plain of the Pine Flats. Above the scarp, the relief 

increases northward. The description of this upper surface 

might be applied without change to the Brandywine Terrace 

at many places on the eastern coast, as the description of 

the surface below the scarp fits the Sunderland where least 

eroded. The altitudes also agree. If scarp line of the terrace 

is continued eastward, it essentially agrees with the southern 

edge of the Southern Pine Hills belt in Mississippi.

Alabama Blue Ridge Mountains—This area comprises 

the southern extreme end of the Blue Ridge Mountains 

of Alabama. It is in contact with the southeastward-lying 

Piedmont Plateau, with the Great Valley (Coosa River) to 

the northwest, and is bounded on the southwest by the Fall 

Line Hills. On the western edge of the Piedmont rise the 

Talladega, Cheaha, and Rebecca Mountains and low hills, 

together constituting a low monadnock range 50 miles long, 

in line with the Great Smoky Mountains, though many 

miles removed from them. These low ridges represent what 

would have been a continuation of the mountain range had 

the uplift been greater and the expansion of the newer peneplain less easy. The Cheaha and Rebecca Mountains are 

formed by undifferentiated sandstones and conglomerates. 

The lowlands to the southeast are underlain by Talladega 

slate and Hillabee schist and amphibolite and Ashland mica 

schist. 

These lowlands are the dissected remains of uplands and 

have relief of 100 feet or more. Longleaf pine occurs here, 

both in the lowlands and on the mountains of the area as a 

present day disjunct. 

Physiography summary—The apparent unifying features 

of the longleaf region are the more or less continuous conditions of physiography and soils from the Brandywine 

and Coharie Terraces in North and South Carolina and 

Georgia, the Tifton Upland in Georgia, and the Central 

Highlands of Florida, through the Southern Pine Hills of 

Alabama, Mississippi, northwest Florida, and northeastern 

Louisiana, to the Kisatchie Terrace and Uplands of central 

Louisiana and east Texas. The lithology of this belt is 
11

generally contemporaneous with the Pliocene Citronelle 

formation. This continuity exists, of course, across the 

several climatic zones of the longleaf region. These physiographic sections are included in the middle Coastal Plain 

province of Lobeck (1948) (fig. 2). The Wicomico, Talbot 

(Pensacola), and Pamlico Terraces are considered to be 

included in the lower Coastal Plain, whereas the Fall Line 

Hills or Sandhills are considered as being included in the 

upper Coastal Plain.

Soil Orders and Suborders

General—The soils that occur in the longleaf pine region

include members of five orders under the Seventh Approximation (Soil Survey Staff 1960). These orders include 

Alfisols, Entisols, Inceptisols, Spodosols, and Ultisols. 

Several of the suborders are also included (fig. 4). Under the 

1938 classification these would include the Alluvial, Bog, 

Half-Bog, Gray-Brown Podzolic, Reddish-Brown, Lateritic, 

Lithosolic, Planosolic, and Red-Yellow Podzolic great soil 

groups (U.S. Department of Agriculture 1938).

These soils range from very deep excessively drained sands 

to poorly drained clays, with or without one or more fragipans in the profile. These soils are derived mainly from the 

marine sediments of the Atlantic and Gulf Coastal Plains 

except in a portion of the longleaf region that occurs in 

northern Alabama. The latter soils are derived from the 

schist, phyllite, slate, sandstone, and conglomerates of the 

extreme southern end of the Blue Ridge Mountains.

Approximately 16 soil associations were recognized as 

occurring in the longleaf region under the 1938 classification. The closest equivalent under the Seventh Approximation is the family category, although the two units do not 

have similar definitions. The family category holds the most 

promise for usefulness to the site evaluator, since it is based 

on grouping of soil series with respect to their similar effect 

on, and response of, plant growth and yield.

Each of the orders and the included suborders will be 

described together with several representative series in their 

respective families. No attempt was made to give lengthy 

definitions at the time this was written in 1965. Familiarity 

with the Seventh Approximation was assumed.

Alfisols—These are soils having a subsurface horizon that 

contains an accumulation of clay and a base saturation 

exceeding 35 percent. The suborder predominant in the 

area is the Udalf (Alfisols that are usually wet, A3), gently 

or moderately sloping. This area is located in the loessal 

fringe belt along the Mississippi River in Mississippi and 

Louisiana. Representative families and series are: Typic 

Hapludalfs, fine silty, mixed, thermic—Lexington; and 

Typic Fragiudalfs, fine silty, mixed, thermic—Providence.

Entisols—The Entisols are soils either without natural 

genetic horizons or with only the beginnings of horizons. 

They thus include many but not all of the previously called 

alluvial soils, Regosols, Lithosols, Tundra soils, and LowHumic Gley soils. The central concept of Entisols includes 

soils in deep regolith or earth with no horizons except a 

plow layer. The soil may be of any color common to soils 

as color is not of significance for this classification. Some, 

particularly the sandy ones, may have thick albic horizons 

(bleached A2 horizons) lying on B horizons that contrast 

strongly in color but show little contrast in any other respect.

The predominant suborder in this area is the Psamments 

(sandy Entisols, E3). These are Entisols that are usually 

moist in some horizon or layer and that have textures coarser 

than loamy fine sand to depths of 20 inches or more. They 

are not saturated in any season and do not have artificial 

drainage. They include sands that have been in place too 

short a time to develop diagnostic horizons other than an 

albic horizon, as well as sand so rich in quartz and other 

unweatherable minerals that no diagnostic horizons other 

than an albic horizon can be developed. They range from 

the calcareous sands on natural levees or recent dunes to the 

quartz sands commonly found on perhumid Coastal Plains.

These soils are located in or make up the Sandhills of the 

Carolinas and Georgia, the sand hills surrounding Treutlen 

County, Georgia, the sandy ridges of the Sunderland Terrace

(Central Highlands) of peninsular Florida, and the Sandhills 

of northwestern Florida and southeast Alabama. The representative families and series are: Typic Quartzipsamments, 

siliceous, acid, thermic, coated—Alaga (Lakeland); Spodic

Quartzipsamments, siliceous, acid thermic, coated—Lakewood; Ultic Quartzipsamments, siliceousphosphatic, acid, 

thermic, coated—Gainesville; and Aquic Quartzipsamments, 

siliceous, acid, thermic, coated—Blanton. 

Inceptisols—These are soils with one or more of the diagnostic horizons that are thought to form rather quickly and 

that do not represent significant illuviation or eluviation or 

extreme weathering. They are most often found on young 

but not recent land surfaces. 

The order includes many of the soils that have been called 

Brown Forest soils, Subarctic Brown Forest soils, Tundra, 

Ando soils, Sols Bruns Acides, Lithosols, and Regosols, and 

a number of associated soils that have been called Humic 

Gley and Low-Humic Gley soils. It includes soils that are 

usually moist and that have no spodic, argillic, nitric, calcic, 
12

gypsic, salic, or oxic horizon, or plaggen epipedon, but that 

have conductivity of the saturation extract of < 1 millimho/

cm at 25 °C, and that have one or more of the following: 

a histic, umbric, or ochric epipedon, a cambric horizon, a 

fragipan, or a duripan. Since argillic and spodic horizons are 

absent there cannot be evidences of significant illuviation. 

Typically, textures are uniform or nearly so.

The predominant suborder is the Aquepts, which are 

Inceptisols that are saturated with water at some season of 

the year or that have artificial drainage and have a diagnostic horizon at a depth of < 20 inches. The representative 

families and series are: Aeric Cumulic Haplaquepts, coarse 

loamy, mixed, acid, thermic—Mantachie; and Cumulic 

Haplaquepts coarse loamy, mixed, acid, thermic—Bibb.

Spodosols—The Spodosols include primarily the soils 

that have been called Podzols, Brown Podzolic soils, and 

Ground-Water Podzols. Not all soils called Podzols are in 

this order. All mineral soils are included that have a spodic 

horizon thick enough to be demonstrable after plowing 

and cultivation for a few years. They are found only in 

humid regions, and mainly under a coniferous forest. The 

parent materials are usually siliceous. So far as is known, 

Spodosols do not form in clayey parent materials. In the 

tropics, the only parent material of the Spodosols seems to 

be nearly pure quartz sand. In addition to the spodic horizon, 

a number of other diagnostic horizons may be present. 

These include histic, umbric, ochric, and possibly anthropic 

epipedons. Argillic horizons, duripans, and fragipans may 

also be found.

These soils have an accumulation of free sesquioxides and 

organic matter in a subsurface horizon. The predominant 

Suborder is the Aquods (wet Spodosols) with Histosols and 

Psamments of the Entisols. The soils are found on the flatwoods or the lower terraces—Wicomico, Talbot (Pensacola), 

and Pamlico Terrace—Florida. The representative families and series are: Typic Haplaquods, sandy, siliceous, 

thermic—St. Johns; and Aeric Haplaquods, sandy, siliceous, 

thermic, noncemented—Leon; and Arenic Haplaquods,

sandy siliceous, thermic, coated—Immokalee.

Ultisols—The Ultisols have a subsurface horizon that 

contains an accumulation of clay and has base saturation of 

< 35 percent. They are restricted to humid climates from the 

temperate zones to the tropics. Land surfaces are commonly 

old, or if they are of late Pleistocene age, the parent materials were highly weathered before they were deposited. The 

native vegetation may have been forest, savanna, or even 

marsh or swamp flora.

The Ultisols have no oxic or nitric horizons, but they have 

an argillic horizon. The argillic horizon is not permitted to 

have tongues of an albic horizon penetrating from the top. 

In addition, the Ultisols may have a mollic, umbric, ochric, 

or histic epipedon or a fragipan. Plinthite is often present. 

These horizons and the plinthite are used to define classes of 

the Ultisols. The content need not be large, but there must be 

enough for identification.

Two suborders are represented in this order in the longleaf 

region. Aquults (U1) are wet Ultisols, gently sloping and 

found on the flatwoods of the lower Coastal Plain in the 

Carolinas and Georgia, and again in Louisiana and east 

Texas (Wicomico, Talbot, and Pamlico Terraces) (fig. 4). 

The Aquults have been called Low-Humic Gley and Humic 

Gley soils. They are saturated at some season or have 

artificial drainage. Representative families and series are: 

Typic Ochraquults, clayey, mixed, thermic—Bladen and 

Coxville of the Carolinas and Georgia, and fine silty, mixed, 

thermic—Caddo of Louisiana and Texas; and the Aquic 

Hapludults, fine silty, siliceous, thermic—Beauregard of 

Louisiana and east Texas, and clayey, kaolinitic, thermic—

Dunbar of the Carolinas and Georgia.

The second suborder represented is the Udult (U3), gently 

or moderately sloping, and the gently to steep phase (U38). 

The former are Ultisols that are usually moist, and these 

occur extensively on the middle Coastal Plain, especially 

the Brandywine and Coharie Terraces of the Carolinas and 

Georgia, and the Tifton Upland of the latter State. Also, 

they occur on the Southern Pine Hills of southern Alabama 

and Mississippi, and the Kisatchie Terrace of Louisiana and 

east Texas. Representative families and series are: Typic 

Hapludults, fine loamy, siliceous, thermic—Bowie, Norfolk, 

and Ruston of the Brandywine, Coharie, and Sunderland 

Terraces of the Carolinas, together with the Plinthic 

Hapludults, fine loamy, siliceous, thermic—Carnegie and 

Tifton of the Brandywine Terrace and the Tifton Upland 

of Georgia and the Southern Pine Hills of south Alabama; 

and Typic Hapludults, clayey, mixed, thermic—Shubuta, 

with Ruston and Bowie in the Southern Pine Hills of 

southern Mississippi and northeastern Louisiana, and the 

upper Coastal Plain of northern Alabama; and the Typic 

Hapludults, clayey, kaolinitic, thermic—Faceville and 

Magnolia of west central Georgia and a portion of southeastern Alabama, and the Bowie and Shubuta families of the 

Kisatchie Terrace of Louisiana and east Texas.

The Udults, gently sloping to steep phase, are found in the 

southern end of the Blue Ridge Mountains of east central 

Alabama. Some soils of the Piedmont Plateau may also be 

included. Families and series representative of this Suborder 
13

are: Typic Hapludults, fine loamy, mixed, mesic—Tate, and 

clayey, micaceous, thermic, thin—Fannin. 

Soils Summary—It appears that the Ultisols are the dominant soil order of the longleaf region. These occur throughout

the longleaf region in the Carolinas and Georgia, Alabama, 

Mississippi, Louisiana, and Texas. The secondary order 

would be the Entisols, suborder Psamments, which occur 

in the Sandhills of the Carolinas and Georgia, the Central 

Highlands of Florida and the Sandhills of northwest Florida, 

and the sandy outliers in southeast Alabama and southeast 

Georgia.

The most representative soil families of the longleaf region

may be the Typic Hapludults, fine loamy, siliceous, thermic—

which includes Bowie, Norfolk, Ruston, Orangeburg and 

others; Typic Quartzipsamments, siliceous, acid, thermic, 

coated—Alaga (Lakeland); and the Plinthic Hapludults, fine 

loamy, siliceous, thermic—Carnegie and Tifton.

The Longleaf Site Zones

The foregoing discussion seems to indicate that site zones in 

the longleaf forest region could be distinguished mainly on 

the basis of climatic differences. This conclusion is based on 

the fact that the physiographic conditions are generally more 

uniform on a broad scale than is climate. The vegetation 

(the longleaf forest) is uniform in a very broad sense. Soils 

vary widely within physiographic provinces due to local 

differences in parent material and topography, and require 

subdivision to that point. Hence, localities first separated 

on the basis of climatic differences, then on physiographic 

or soils differences, or both, should be homogeneous with 

respect to the three factors. It must be borne in mind that the 

boundaries of these areas and zones are tentative until more 

information is available on the exact relationships between 

tree growth and the environment, and are to be revised or 

eliminated depending on subsequent research results.

I. The Carolinas area—The area includes the Coastal 

Plains of the Carolinas. The southern boundary is the 

South Carolina-Georgia border, which coincides with 

Thornthwaite’s 39.27 inches potential evapotranspiration 

line. The western boundary is the edge of the Piedmont 

Plateau physiographic province.

Three homogeneous zones occur in this area. One is the Fall 

Line Sandhills of the upper-middle Coastal Plain, with soils 

characterized by Typic Quartzipsamments of the Entisols. 

The second zone contains the Brandywine and Coharie 

Terraces of the middle Coastal Plain. Its soils are characterized by the Typic Hapludults of the moist Ultisols. The third 

zone lies on the terraces of the lower Coastal Plain and is 

characterized by the Typic Ochraquults of the wet Ultisols.

The area’s average annual rainfall varies from 43 to 50 

inches, and the annual mean temperature ranges from 61 

°F to 66 °F. The line between the middle and lower Coastal 

Plains also acts as a climatic boundary and some minor 

climatic differences exist between these two physiographic 

provinces. The area as a whole is generally cooler and drier 

than the Georgia area lying to the southwest.

II. The Georgia area—This area includes a portion of 

northwest Florida and southeast Alabama, and lies southwest

of the Carolinas area. The Georgia area is bordered on the 

north by the Piedmont Plateau. The southern boundary 

extends along the coastal lowlands of Georgia, southward 

across north-central Florida and westward to the gulf, southwest of Tallahassee, FL. This city lies on the boundary. The 

area comes under the influence of both Atlantic and Gulf 

storms and differs from the Carolinas in having two rainfall 

peaks rather than one. It is also characterized by greater 

divergence between the rainfall patterns of the warming and 

cooling cycles. The annual mean temperature ranges from 

66 °F to 68 °F and rainfall varies from 44 to 58 inches

annually.

Three homogeneous site zones occur within this area. The

south-westward continuation of the Fall Line Sandhills 

extends through the central part of the State to the Chattahoochee River, then curves southward to the Florida border. 

The representative soils are the Typic Quartzipsamments. 

These same Entisols also occur in the area surrounding 

Treutlen County at the edge of the middle Coastal Plain, in 

the area surrounding Dale County, Alabama, and a portion 

of the Sandhills of northwest Florida. The majority of the 

land area is composed of the moist Ultisols, Udults, and 

includes the Typic Hapludults of the Dougherty Plain, Tifton 

Upland, and Brandywine Terrace of the middle Coastal 

Plain. Obviously, many other categories are included. A 

small zone of Spodosols occurs on the lower Coastal Plain 

below the Florida Sandhills, along the gulf coast. These 

include mainly the Aquods, which are found further south in 

peninsular Florida. 

III. The Florida area—This area consists of the extreme 

southeastern tip of coastal South Carolina, the lower Coastal 

Plain of Georgia and peninsular Florida, and a portion 

of northwest Florida south and west of Tallahassee. The 

southern boundary is approximately Lake Okeechobee and 

coincides with Thornthwaite’s 44.88 inches evapotranspiration line. The average annual rainfall ranges from 49 to 54 

inches, and annual mean temperature ranges from 69 °F to 
14

74 °F. This area exhibits the patterns of maritime subtropical 

climate with mild temperatures and high rainfall. The 

physiography is mostly that of the lower Coastal Plain. This 

includes the Wicomico, Talbot (Pensacola), and Pamlico 

Terraces along the coasts, and the Sunderland Terrace 

forming the Central Highlands of the peninsula.

Generally, the following elevations are given for the various 

terraces:

 Sunderland Terrace Above 100 feet above 

 mean sea level (MSL)

 Wicomico Terrace 70 feet above MSL

 Talbot (Pensacola) Terrace 42 feet above MSL

 Pamlico Terrace 25 feet above MSL

The soils in this area are represented by the Ultic and Typic 

Quartzipsamments on the Sunderland Terrace, and the Aeric, 

Typic, and Arenic Haplaquods on the lower terraces. 

IV. The Alabama area—The eastern boundary of this 

area is the Georgia area, approximately at Geneva, AL. The 

northern boundary is the southern edge of the Buhrstone 

Cuesta in Alabama and Jackson Prairie in Mississippi. It 

includes northwest Florida and part of southeast Louisiana 

(the Florida parishes). The average annual rainfall ranges 

from 59 to 69 inches and the annual mean temperature 

ranges from 66 °F to 68 °F. This area exhibits two distinct 

and equal maximum monthly rainfall peaks in March and 

July. The difference between the rainfall patterns of the 

warming and cooling cycles is even greater in the Alabama 

area than in the Georgia area. The temperature range is 

somewhat less. The Alabama area differs from the Florida 

area by having two rainfall peaks rather than one. The area 

coincides generally with Thornthwaite’s 20-inch annual 

water surplus line, which is the greatest in the longleaf belt 

and the eight Southeastern States included in this study. This 

area occurs on the widest part of the middle Coastal Plain. 

The Citronelle and the Catahoula formations underlie this 

area. It is a continuation of the physiography that begins in 

the Carolinas on the Brandywine and Coharie Terraces and 

extends through Georgia on the Tifton Upland into Alabama 

and Mississippi. Thus, the area is confined mainly to the 

middle Coastal Plain, although a narrow strip extends along 

the coast in the lower Coastal Plain near Fort Walton Beach 

and Pensacola, FL, westward to Mobile, AL, Gulfport, 

Biloxi, and Poplarville, MS, and Bogalusa and Amite, LA.

As in the Georgia area the predominant soils are the 

Ultisols or more specifically the Udults, which include the 

Typic and Plinthic Hapludults of the middle Coastal Plain 

(Southern Pine Hills). A portion of the Florida Sandhills 

is included in this area, and the Sandhills soils are mainly 

Typic Quartzipsamments. Some Inceptisols (Aquepts) occur 

along the Mobile and Tombigbee rivers in Alabama, and 

along the Pascagoula and Pearl rivers in Mississippi. These 

are Aeric Cumulic and Cumulic Haplaquepts. At the western 

end of this area occur the Alfisols of the loessal belt east 

of the Mississippi River. These include Udalfs of the Typic 

Hapludalfs and Fragiudalfs.

A separate climatic area is recognized within the Alabama 

area. It lies east and north of Mobile Bay, and is an area 

of increased annual rainfall—to about 66 to 69 inches as 

compared with 59 to 63 inches in the remainder of the area.

V. The Louisiana area—The Mississippi Valley and 

its alluvium separate this area from the remainder of the 

longleaf region. It lies in the eastern counties of Texas and 

the parishes of central Louisiana on the Nacogdoches and 

Kisatchie Terraces and the Pine Flats. The climatic pattern 

exhibited indicates the proximity of the area to the soil 

moisture tension zone of the Midwestern United States. The 

4-inch annual water deficit line of Thornthwaite follows 

the Louisiana-Texas border and the area is divided on that 

basis. The annual rainfall for the Texas portion ranges from 

48 to 54 inches, while that in the Louisiana portion ranges 

from 59 to 62 inches. The annual mean temperatures do not 

differ significantly. The Nacogdoches and Kisatchie Terraces 

are more or less a continuation of the physiography of the 

Alabama area and areas further east. They are underlain by 

the same Citronelle and Catahoula formations and give rise 

to approximately the same soils, Typic Hapludults.

The Inceptisols found in the Red River Valley are also found 

in the Louisiana area, but the Red River Valley is not a part 

of the longleaf pine region. The Pine Flats are on the lower 

Coastal Plain and have Aquult soils (Typic Ochraquults). Thus,

the Louisiana area contains four homogeneous site zones.

VI. The Mountain area—Separated from the main portion 

of the longleaf region by the Black Belt physiographic province, the Mountain area has features unlike those of other 

divisions in the region. It is located in the extreme southern 

end of the Blue Ridge Mountains and a portion of the upper 

Coastal Plain in central Alabama. This division is further 

subdivided on that basis. The rainfall of this division ranges 

from 52 to 56 inches annually. The annual mean temperature 

ranges from 62 °F to 64 °F. The topography, more rugged 

than elsewhere in the region, has great influence on microclimates in the division. The soils of the two subdivisions 

differ at the family level but belong to the same subgroup, 

the Typic Hapludults.
15

CONCLUSIONS

Six major areas of the longleaf pine region are recognized 

and can be delineated without difficulty. These 6 areas are 

further subdivided into 21 site zones. Each of these site 

zones is deemed homogeneous with respect to climate, 

physiography, and soils. Each zone, perhaps, should be 

studied individually for the relationships between longleaf 

growth and site. The wealth of literature indicating lack of 

applicability of results outside of the immediate study area 

suggests this approach. Further, Hodgkins (1960) states that 

“The hazards of regression technique can only be avoided 

by working within small, rather uniform areas.” This may 

be considered as extreme detail, but this approach will yield 

a clearer understanding of the growth and site relationships over the longleaf region. The zones found not to be 

significantly different in their factors affecting growth or 

regeneration can be combined later. In some instances it 

may be necessary to carry out a given study in only several 

representative zones; on the other hand, a particular study 

may have to be carried out simultaneously or successively in 

all zones.

It is conceivable that these homogeneous site zones may be 

useful for species other than longleaf pine. However, it must 

be borne in mind that the zones were defined for longleaf 

pine.

LITERATURE CITED

Adams, G.I.; Butts, C.; Stephenson, L.W.; Cooke, W. 1926. Geology of 

Alabama. Spec. Rep. 14. Geological Survey of Alabama. 312 p.

Cooke, C.W. 1945. Geology of Florida. Geol. Bull. 29. Geology Survey of 

Florida. 339 p.

Fenneman, N.M. 1938. Physiography of Eastern United States. New York: 

McGraw-Hill Book Co., Inc. 689 p.

Hodgkins, E.J. 1960. Estimating site index for longleaf pine through quantitative evaluation of associated vegetation. Society of American Foresters 

Proceedings. Bethesda, MD: Society of American Foresters: 28-32.

Hodgkins, E.J. 1965. Southeastern forest habitat regions based on physiography. For. Dep. Series 2. Auburn, AL: Alabama Agriculture Experiment 

Station. 10 p.

Lobeck, A.K. 1948. Physiographic diagram of North America. Maplewood, 

NJ: The Geographical Press. 16 p. + map.

Soil Survey Staff. 1960. Soil classification, a comprehensive system, 7th

approximation. Washington: U.S. Department of Agriculture, U.S. Soil 

Conservation Service. U.S. Government Printing Office. 503 p.

Thornthwaite, C.W.; Mather, J.R.; Carter, D.B. 1958. Three water balance 

maps of eastern North America. New York: Resources for the Future, Inc.

U.S. Department of Agriculture 1938. Yearbook of Agriculture. Soils and 

Men. Washington: U.S. Government Printing Office. 1232 p.

U.S. Department of Agriculture 1941. Yearbook of Agriculture. Climate and 

Man. Washington: U.S. Government Printing Office. 1248 p.

U.S. Department of Commerce Weather Bureau. 1954. Climatic Summary 

of the United States-Supplement for 1931–52. Climatography of the U.S. 

11–17. Washington: U.S. Government Printing Office. 

U.S. Soil Conservation Service. 1964. General soil map of the United 

States: coterminous 48 states by dominant orders and suborders of 

the new soil classification system. Washington: U.S. Department of 

Agriculture, U.S. Government Printing Office. 

Wakeley, P.C. 1953. The South establishes a major pine geographic seed 

source study. In: Proceedings of second southern forest tree improvement 

conference. Atlanta: U.S. Department of Agriculture, Forest Service. 6 p.

Wakeley, P.C. 1959. Five-year results of the southwide pine seed source 

study. In: Proceedings of the fifth southern forest tree improvement 

conference. Raleigh, NC: N.C. State University, School of Forestry: 6-

11.

Wakeley, P.C. 1961. Results of the southwide pine seed source study 

through 1960–61. In: Proceedings of the sixth southern forest tree 

improvement conference. Gainesville, FL: University of Florida, School 

of Forestry: 10-24.

Wakeley, P.C. 1963. How far can seed be moved. In: Proceedings of 

seventh southern forest tree improvement conference. New Orleans: U.S. 

Department of Agriculture, Forest Service: 38-43.

Wells, O.O.; Wakeley, P.C. 1970. Variation in longleaf pine from several 

geographic sources. Forest Science. 16: 28-42.
16

Appendix

Climogram of the 45 Stations Used in the Study

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

61.5 62.8

49.44 47.70

62.9 63.8

46.96 49.84

62.7 65.8

50.10 49.11

Monthly average rainfall (inches)

0 5 10 0 5 10
17

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

63.2 65.4

42.96 44.46

62.3 65.1

45.98 50.01

63.7 69.3

43.47 53.25

Monthly average rainfall (inches)

0 5 10 0 5 10
18

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

66.9 68.6

47.54 47.68

66.5 67.6

44.33 52.53

66.8 73.7

46.60 53.51

Monthly average rainfall (inches)

0 5 10 0 5 10
19

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

70.4 68.6

51.64 66.80

69.2 68.0

50.40 61.60

72.4 67.7

49.11 56.77

Monthly average rainfall (inches)

0 5 10 0 5 10
20

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

62.5 66.1

52.20 61.72

67.5 67.6

69.24 65.70

68.0 67.2

66.76 55.72

Monthly average rainfall (inches)

0 5 10 0 5 10
21

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

64.5 63.6

57.22 52.52

66.6 66.8

59.80 60.49

65.6 67.7

58.63 63.19

Monthly average rainfall (inches)

0 5 10 0 5 10
22

80

60

40

80

60

40

80

60

40

Monthly mean temperature (°F)

67.6 67.5

60.55 60.98

67.6 67.2

62.79 60.42

68.1 66.6

59.03 59.13

Monthly average rainfall (inches)

0 5 10 0 5 10
23

80

60

40

80

60

40

Monthly mean temperature (°F)

67.1 65.8

54.14 47.89

67.9

46.58

Monthly average rainfall (inches)

0 5 10



Craul, Phillip J.; Kush, John S.; Boyer, William D. 2005. Longleaf pine site zones. 

Gen. Tech. Rep. SRS–89. Asheville, NC: U.S. Department of Agriculture, Forest 

Service, Southern Research Station. 23 p.

The authors delineate six major climatic areas of the longleaf pine (Pinus palustris Mill.) 

region. They subdivide these areas into 21 site zones, each of which is deemed homogenous 

with respect to climate, physiography, and soils. The site zones are mapped and their 

climate, physiography, and soils described. The authors recommend that plantings of 

longleaf pine in any of the six major climatic areas of the longleaf region be made with a 

seed source from the same area.

Keywords: Climatic zones, longleaf pine, physiographic provinces, Pinus palustris, site 

zones, soils.
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