United States

Department of

Agriculture

Forest Service

Southern 

Research Station

General Technical 

Report SRS–153

Guidelines for Regenerating 

Southern Pine Beetle Spots

J.C.G. Goelz, B.L. Strom, J.P. Barnett, and M.A. Sword Sayer
Authors:

Jeffery C.G. Goelz, Research Forester (retired); Brian L. 

Strom, Research Entomologist; James P. Barnett, Emeritus 

Scientist; and M.A. Sword Sayer, Plant Physiologist, U.S. 

Department of Agriculture, Forest Service, Southern Research 

Station, Pineville, LA 71360.

April 2012 

Southern Research Station 

200 W.T. Weaver Blvd. 

Asheville, NC 28804

www.srs.fs.usda.gov

Cover: Longleaf pine regeneration. (Photo courtesy of Erich Vallery, 

USDA Forest Service, Southern Research Station, Pineville, LA)
Abstract

Southern pine forests are of exceptional commercial and ecological 

importance to the United States, and the southern pine beetle is their most 

serious insect pest. The southern pine beetle generally kills overstory pines, 

causing spots of tree mortality that are unpredictable in time and space and 

frequently disruptive to management activities and goals. The canopy gaps 

created may be large enough for regeneration activities to be considered, 

but the nature of southern pine beetle spots, and the residual stands of 

which they are a part, can make regeneration decisions complex. Spot size 

and shape, stand age, structure, silvicultural system, product markets, and 

management goals all are important determinants for obtaining successful 

regeneration of southern pine beetle spots. This paper provides a key to 

assist managers faced with the complexities of regenerating southern pine 

beetle spots in the context of the larger stand. Guidance is provided for 

the application of regeneration methods that are appropriate for particular 

management objectives, spot sizes, stands, and environmental conditions. 

Keywords: Forest management, overstory pines, regeneration, residual 

stands, southern pine beetle spots.

INTRODUCTION

Southern pine forests are of exceptional commercial and 

ecological importance to the United States. Principal 

commercial species are loblolly pine (Pinus taeda), slash 

pine (Pinus elliottii), longleaf pine (Pinus palustris), and 

shortleaf pine (Pinus echinata). Loblolly pine, by far the 

most widely distributed and commercially important forest 

tree species in the South (Baker and Langdon 1990), is 

frequently affected by southern pine beetle (Dendroctonus 

frontalis) (SPB) infestations. All four species are susceptible 

to SPB, but slash and longleaf pines are considered more 

resistant, presumably due to greater quantities of oleoresin 

exudation that can “pitch-out” and kill attacking beetles (fig. 1).

The SPB is the most serious insect pest of nonjuvenile 

pine forests in the Southeastern United States. Successful 

reproduction requires host death, so impacts of this pest 

on forest health are primarily a result of overstory pine 

mortality. Unlike most native insects, SPB kills its hosts in 

clumps, called spots, which are mostly continuous areas of 

complete pine tree mortality (fig. 2). SPB spots may require 

intervention from managers, both to stop their progression 

and to regenerate stands following their occurrence. 

Populations of SPB vary dramatically in time and space. In 

most years, there are outbreak populations somewhere in 

the Southern United States, but populations in a particular 

location come and go. Population fluctuations are dramatic 

and unpredictable, causing extreme variability in pine 

mortality (fig. 3). 

In addition to SPB population density, the risk of spot 

formation is significantly affected by site, stand, and 

environmental factors. Forest health determinants such 

as tree vigor, stand density, and age are important for 

determining risk of infestation. When tree mortality 

occurs, it is rapid, causing overstory gaps to form quickly. 

Depending on stand structure and beetle populations, gaps 

may be large or small, diffuse or discrete. Large gaps—

and potentially small gaps that can be coalesced—may be 

regenerated with the usual techniques (Barnett and Baker 

Guidelines for Regenerating Southern 

Pine Beetle Spots

J.C.G. Goelz, B.L. Strom, J.P. Barnett, and M.A. Sword Sayer

Figure 1—The volume of oleoresin exuded from beetle attack sites is 

thought to be the most important resistance factor that a tree can employ 

against bark beetle attack. A copious flow of resin may kill attacking beetles 

and prevent tree mortality. (Photo courtesy of Erich Vallery, USDA Forest 

Service, Southern Research Station)
Figure 2—Southern pine beetle infestations, called spots, are usually relatively small with mostly continuous pine mortality within their boundaries. Thus, they 

are similar to group selection cuts for reforesting options. (Photo courtesy of Frank M. Riley, Jr., Georgia Forestry Commission, Bugwood.org [UGA1348016])

Figure 3—Populations of southern pine beetle are unpredictable and vary dramatically across time and space causing extreme 

variability in pine mortality. Outbreaks are defined as the presence of at least 3 spots per 1,000 acres of susceptible host type. 

(Image from Pye and others 2005)

State with infrequent reporting

None

1–3

4–6

7–12

13–28

2
1991), and future stands may be made less susceptible to 

SPB through lower planting densities, planting resistant 

species or perhaps more resistant families, and maintaining 

the vigor of individual trees by intermediate stand 

management activities. Small gaps are common following 

SPB infestation and offer particular challenges to forest 

managers (see Special Considerations in Regenerating SPB 

Spots in this report).

In summary, SPB-caused mortality of overstory pines 

can be severe, but is unpredictable in time and space. 

Resulting canopy gaps may impact management of a stand, 

in particular the decision to replant. This paper provides 

guidance for the application of regeneration methods 

appropriate for particular management objectives, spot sizes, 

stands, and environmental conditions. 

REGENERATION METHODS 

OF SOUTHERN PINES

Southern pines can be regenerated naturally—by seeds from 

trees growing on or adjacent to the site—or artificially—by 

direct seeding or planting seedlings. Techniques for applying 

these methods are described by Barnett and Baker (1991). 

Most landowners have several options for regenerating 

their forest lands, the best choice being largely influenced 

by their objectives. The southern pines can be regenerated 

naturally with clearcutting, seedtree, shelterwood, or 

selection reproduction cutting methods (fig. 4). Good 

natural regeneration requires an adequate, high-quality seed 

source. Seeding characteristics of the southern pines vary 

with species, physiographic region, climatic factors, and 

Figure 4—Natural regeneration by several methods: (A) Clearcutting in strips: Seeds are provided by adjacent stands. (B) Seed in place: 

Stand is clearcut after cone maturity and peak seedfall but before germination. (C) Seedlings in place: Stand is clearcut in late summer 

following a good seed year. (D) Seedtree: All but 4 to 20 trees per acre, depending on species and size, are cut. (E) Shelterwood: All but 

30 to 50 trees per acre, comprising a basal area of 20 to 30 square feet per acre, are cut. (Adapted from Williston and others 1982)

3
minimum size of gaps requiring mandatory planting may 

also change. Currently, many managers use 10 acres as the 

minimum size required for triggering regeneration practices. 

Success in regenerating smaller spots is adversely affected 

by resource competition from the larger remaining trees 

at the gap edge (McGuire and others 2001); seedlings 

closer to the edge are more affected (fig. 8). Growth of 

established seedlings increases linearly from the gap edge to 

the interior portion of the gap (McGuire and others 2001). 

Differences in seedling establishment and growth in the gap 

occur at roughly 30-foot increments (fig. 8, generated from 

Brockway and Outcalt 1998, Gagnon and others 2003). 

Moving from the gap edge, the outer 30 feet (C, fig. 8) 

comprise a seedling exclusion zone where establishment is 

Figure 5—Planting of longleaf pine seedling by hand using a 

dibble bar. Such planting would be appropriate in small gaps 

where machine planting is not feasible. 

Table 1—Seeding characteristics of southern pines for average sites

Species

Frequency 

of seed 

crops a Period of peak seedfall

Effective 

distance of 

dispersal

Largest square 

spot that may 

be regenerated

in acres b Citation

years feet 

Loblolly 2-4 Late October-November 200-300 8.3 Baker and Balmer 1983

Shortleaf 3-6 November 200-300 8.3 Lawson and Kitchens 1983

Longleaf 3-5 Late October-November 60-70 0.45 Boyer and Peterson 1983

Slash 3 October 150-250 5.7 Shoulders and Parham 1983

Sand 4-6 October 200-250 5.7 Outcalt and Balmer 1983

Table Mountain 2-4 Late October-November 200-250 5.7 Della-Bianca 1990

a A seed crop is considered good when an adequate number of seeds are distributed to regenerate an area under average conditions. For 

loblolly and shortleaf pines, 80,000 seeds per acre is considered a good seed crop. About 50,000 seeds per acre is the minimum needed to 

adequately restock a prepared seedbed.

b Calculated as the square of twice the effective dispersal distance. This assumes that dispersal is multidirectional. If dispersal is unidirectional 

with the prevailing winds, the size should be one-fourth the number provided.

tree and stand conditions. Some of these characteristics 

are summarized in table 1. Alternatively, regeneration can 

be done artificially, by direct seeding or planting container 

or bare-root nursery seedlings (fig. 5). However, when 

regenerating SPB spots, the scope of these options is 

reduced. Once the decision has been made to regenerate a 

spot, the unusual and heterogeneous seedling environments 

created by the SPB infestation require consideration before 

successful regeneration can be assured.

SPECIAL CONSIDERATIONS IN 

REGENERATING SPB SPOTS

The geometry of small spots creates special circumstances 

for regenerating pine seedlings. Trees remaining from 

the original stand compete with seedlings for sunlight, 

water, and nutrients, making spot edges inhospitable for 

pine regeneration (fig. 6). Hardwood competition will 

be prevalent in gaps and typically must be controlled for 

successful regeneration of pines. 

Typical regeneration practices are designed for 

implementation at the stand level, while SPB spots usually 

represent only a small portion of a stand. Most SPB spots 

are < 1 acre and extinguish themselves (Porterfield and 

Rowell 1981) (fig. 7); however, spots can be significantly 

larger and require management interventions for their 

control. While no estimates are available for the average 

size of SPB spots that were controlled with tree cutting, 

the Forest Service, U.S. Department of Agriculture defines 

a gap of 5 acres as the minimum necessary for mandatory 

replanting. However, as economic conditions change, the 

4
Figure 6—A small southern pine beetle spot where killed pine trees were felled to control beetle activity. The small size, edge effects, and 

competition make this spot difficult to regenerate. (Photo courtesy of Ronald F. Billings, Texas Forest Service, Bugwood.org [UGA0284008a])

Figure 7—A small southern pine beetle spot typical of many that extinguish themselves naturally. (Photo courtesy of Erich Vallery, USDA 

Forest Service, Southern Research Station, Bugwood.org [UGA0745093])

5
unacceptable; the next 30 feet (B, fig. 8) comprise a zone 

of diminished seedling growth; while the center of the 

gap (A, fig. 8) allows undiminished growth. We consider 

the regenerable area1 of a circular gap to consist of zones 

A and B in figure 8. The size and shape of the spot, and 

the characteristics of the surrounding stand, determine the 

resources available to seedlings within the newly created 

gap. These characteristics affect seedling survival, growth, 

and establishment, and must be considered for regeneration 

to be successful.

GUIDELINES FOR MANAGERS

The objectives of the land manager and his or her 

available resources help guide the response following SPB 

infestations. Appropriate decisions regarding reforestation 

of gaps should be determined from these objectives, as 

well as the type of stand affected and characteristics of the 

infestation. Goals such as timber production, management of 

game and nongame species, preservation of water resources, 

and sustained recreational use may impact regeneration 

opportunities and will be prioritized differently depending 

on landowner objectives.

1

 We define the regenerable area as the area of a gap in which growth and 

survival of tree seedlings is not severely reduced by competition from the 

neighboring intact forest.

Stand Conditions

Principle stand characteristics that affect management 

responses to SPB mortality are: silvicultural system being 

used; stand age, size, and origin; and spatial characteristics 

that may facilitate or hinder operations.

Uneven-aged stands regularly have regeneration cuts that 

remove a portion of the stand as groups, individual trees, 

or both. Generally, smaller SPB spots will not compromise 

uneven-aged management unless there are many of them in 

a stand. Though natural regeneration is typically employed 

in uneven-aged management, artificial regeneration may be 

required if spots are large and advance regeneration is not 

present.

In an even-aged stand, regeneration decisions will depend 

upon the age and size of the stand and intensity with which 

the landowner chooses to manage. Older stands that are near 

rotation age generally do not warrant reforestation until final 

harvest of the surrounding stand. If the forest is managed on 

a long rotation, and beetles infest a relatively young stand, 

the regenerated spot may achieve sawtimber size before the 

final harvest. If the surrounding stand is large, the landowner 

may decide that regeneration of a limited number of spots is 

not economically warranted.

Economic Considerations

Although regeneration of small spots can be biologically 

feasible, carrying out such regeneration practices may not be 

economically justifiable. For example, it may not be possible 

to contract salvage harvesting of relatively small spots. 

Also, spots of 10 to 15 acres (or more depending on spot 

configuration) may be naturally regenerated by seed from 

surrounding stands. Landowner management objectives will 

affect the nature of regeneration options applied and may 

modify their application. 

Characteristics of the Infestation

Characteristics of the SPB spots within a stand, and 

potentially in nearby stands, may influence the manager’s 

reforestation decisions. Pertinent characteristics are spot 

size, number of spots, cumulative area of the spots, and 

distribution of spots within the stand (i.e., diffuse, clumped, 

or discrete). For regeneration considerations, spot size 

should include any buffer area that would be harvested to 

limit spread of the infestation.

Generally, reforestation is more practical when spots are 

large or a number of spots can be combined to create 

economies of scale. While alternatives to normal sanitation 

practices may be used, regeneration practices will be 

hindered unless dead, dying, and buffer trees are felled 

and either removed or burned. Thus, all management 

Figure 8—Regeneration zones in a gap in a pine forest. Extending 26 feet 

from the forest edge is the “regeneration exclusion zone,” C, dark grey. The 

light grey zone, B, is the “area of diminished growth,” which extends 59 

feet from the forest edge. The white area, A, is the “area of undiminished 

growth.” The radius, ru represents the radius of the opening minus 59 feet. 

The area of undiminished growth refers to growth of seedlings and small 

saplings; for larger trees, growth may be reduced relative to similar trees 

growing in even-aged stands. The white and light grey areas, together, 

comprise the “regenerable area” of the gap.

C

B

A

r

u 33’ 26’

6
recommendations will be made for stands in which one or 

more spots are salvaged. There are no practical regeneration 

opportunities for small SPB spots that have not been 

salvaged (fig. 9). The retention of some dead trees may be 

acceptable to promote populations of natural predators of 

SPB or wildlife habitat. However, all trees currently infested 

with SPB and buffer trees should be felled and removed 

prior to the onset of regeneration activities.

KEY FOR MANAGEMENT DECISIONS

The following key is meant to provide a suggested course 

of action to regenerate SPB spots. It is meant as a guide for 

managers; reality is more complex than can be contained in 

any such key. The major value of the key is to help managers 

organize useful information so that the best course of action 

can be determined. The main underpinnings of the key are: 

(1) without a gap in the forest canopy, there is no point in 

viewing SPB spots as a regeneration opportunity; (2) if the 

stand is uneven-aged, or destined to be uneven-aged, any 

salvage should be considered a regeneration opportunity; 

(3) if the stand is even-aged, destined to be naturally 

regenerated, and close to final rotation, salvage of the spots 

should be integrated into a preparatory or final regeneration 

harvest; (4) southern pines are shade-intolerant making 

even-aged management the path of least resistance; (5) 

spot size must be large enough to provide an environment 

conducive to even-aged regeneration; (6) if wildlife habitat 

is a primary goal, it is not critical that all acres produce 

timber; (7) some managers may want to change stand 

composition; (8) regeneration practices should be integrated 

with treatment of the parent or adjacent stands; (9) unless 

stand age is very far from rotation age, the regenerated spots 

will never “catch up” to the surrounding stand; and (10) 

vegetation will always develop in the spot. In the absence 

of management, this will frequently be a mixture of loblolly 

pine and associated hardwood species. 

Prescriptions

These prescriptions assume that the land manager has a 

suite of silvicultural options available. Thus, details about 

silvicultural practices are only provided when they differ 

from standard practices. For example, the manager probably 

has particular site preparation and vegetation management 

practices that they use for conventional regeneration, and we 

do not advocate changes to these protocols.

Prescription A—In an uneven-aged stand, SPB spots may 

be considered opportunities to integrate sanitation cuts 

into regeneration harvests. Removal of groups of trees and 

individual trees in dense portions of the stand can lessen the 

risk of future infestations in the stand. However, any harvest 

should be timed to minimize risk of site disturbance causing 

additional beetle problems.

Prescription B—Management will rely on natural 

regeneration because the spots are sufficiently small that 

supplemental planting will not be needed. However, natural 

regeneration success is subject to seedbed characteristics. 

The seedbed may be prepared by prescribed fire, mechanical 

Figure 9—Southern pine beetle spot with overstory mortality and lack of pine salvage or felling. Without use of prescribed fire 

to reduce vegetative development, there is no opportunity for regeneration under these conditions of understory development. 

(Photo courtesy of David J. Moorhead, University of Georgia, Bugwood.org [UGA0010165]) 

7
A key to assist forest managers with regeneration decisions

 following stand disruption by southern pine beetle

This key consists of a series of two-part dichotomous statements (bulleted) that describe characteristics of southern 

pine beetle spots, the stands in which the spots occur, or possible management objectives. Each number in the key 

provides the manager with a choice between two options, each of which leads to an additional choice (one of the next 

consecutively numbered steps) or to a prescription that we estimate will best meet the manager’s needs.

Step Characteristics Prescription or 

next step

1 • Stand currently uneven-aged or to be converted to uneven-aged 2 

• Stand under even-aged management 4 

2 • Sufficient natural regeneration in spot Prescription A

• Natural regeneration in spot is insufficient or absent 3 

 

3 • Individual spots narrower than dispersal distance for dominant pines (table 1), at least 20 living 

dominant or codominant seed-bearing pines per acre are present in surrounding stand 

Prescription B

• Individual spots wider than dispersal distance for dominant pines, or fewer than 20 living 

dominant or codominant seed-bearing pines per acre are present in surrounding stand

Prescription C

4 • Spot is larger than manager’s criterion for minimum stand size 5

• Spots are smaller than manager’s criterion for minimum stand size 8

 

5 • Stand is within 2 years of being regenerated Prescription D

• Stand will not be regenerated soon 6

6 • Future plan for stand is artificial regeneration Prescription E

• Future plan for stand is natural regeneration 7

 

7 • Individual spots narrower than dispersal distance for dominant pines, and 20 or more dominant or 

codominant seed-bearing pines per acre are present surrounding the spot

Prescription B

• Individual spots wider than dispersal distance for dominant pines, or neighboring seed-bearing 

trees are insufficient

Prescription C

8 • Multiple spots are sufficiently clustered that a reasonable increase in buffer width will coalesce 

spots into areas greater than manager’s criterion for minimum stand size

Prescription F

• Spots are solitary or scattered 9

 

9 • Spots are all undersize for salvage, and final harvest is scheduled within 25 years Prescription G

• Spots are large enough for salvage treatments and are not scheduled for harvest within 25 years 10

10 • Stand is mixed-species, but most of the pine species composition has been lost 11

• Species composition of the stand as a whole has been little affected 13

 

11 • Stand is of low value for management objectives and value is not likely to improve Prescription H

• Stand currently achieves, or has the potential to achieve, most of the important management 

objectives

12

12 • Manager desires to increase the component of a pine species Prescription I

• Manager does not desire to change species composition Prescription J

 

13 • Manager desires to change species composition1 Prescription K

• Manager has no preconceived desire to change species composition 14

14 • Timber production is secondary to other forest uses Prescription L

• Timber production is the primary objective for the forest Prescription M

1

 A manager may desire to change species composition to more fully achieve management objectives, to restore under-represented habitat (e.g., longleaf 

pine), or to reduce future risk of southern pine beetle infestation (by planting less susceptible species). 

8
site preparation, or both. Often, logging operations can 

prepare the seedbed. Because seedfall declines with distance 

from a forest edge, attempt to improve the uniformity of 

regeneration by intensifying site preparation as distance 

from the forest edge increases. If the desired species is 

lacking along part of the spot margin, consider supplemental 

planting or seeding. This will provide an opportunity to 

introduce one or more species that are absent from the 

surrounding stand. Depending on the likelihood of desirable 

natural regeneration, supplemental planting density will 

be location-specific but less than that typically used in 

plantations.

Prescription C—Although natural regeneration is desired 

by the manager, the spot is too large to rely on natural 

regeneration unless it is already in place. Supplemental seed 

or seedlings are needed to attain adequate regeneration. 

If the surrounding stand has an insufficient number of 

seed bearing trees of the desired species, supplemental 

planting over the entire spot is indicated. If the spot is 

simply too large for adequate seedfall across the entire 

area, supplemental seeding or planting is suggested in 

part of the spot while the center of the spot may require 

planting at conventional rates for plantations. Beyond these 

considerations, the spot is large enough to allow standard 

practices for regeneration. If the manager prefers natural 

regeneration, broadcast direct seeding may produce stands 

more similar to naturally regenerated stands. Closer to the 

edge, the manager may rely on natural regeneration or may 

broadcast seeds at a lower rate. The site must be adequately 

prepared prior to seeding. Logging operations or burning 

may provide a suitable seedbed. Seeding is not appropriate 

where soils are likely to be flooded, very dry, grazed, or 

eroded following seeding. 

Prescription D—Delay regenerating spots until the 

surrounding stand is harvested and use the practices 

planned for that stand. When even-aged management is 

preferred, it makes little sense to complicate management by 

regenerating spots when the surrounding stand is scheduled 

for regeneration in the near future. The definition of “near 

future” depends somewhat on management intensity. 

Where economic goals suggest that the entire forest must 

be productive, near future represents 1 to 2 years. When 

management is mainly concerned with providing nontimber 

forest products, a delay of 10 to 20 percent of the final 

rotation age may be tolerable. 

Prescription E—Regenerate spots by conventional 

practices used by the manager. Trees need not be planted 

closer than 30 feet to surviving trees at the surrounding 

forest edge. If practical, identify spots as new stands to 

facilitate subsequent management. Protect regeneration 

from damage related to silvicultural practices conducted in 

surrounding stand.

Prescription F—Small spots are difficult to regenerate, or, 

if regenerated, do not produce usable timber products by the 

time the surrounding stand is harvested. Also, regenerating 

small spots is expensive. Thus, it may be prudent to increase 

the buffer area around the spot so that nearby spots are 

combined into one, more manageable area. Guidelines 

on combining versus not combining spots are difficult 

to provide because local conditions and management 

objectives often prevail. However, a manager should 

consider combining spots into a single management unit 

when: (1) spots would coalesce if buffer areas are expanded 

< 60 feet, (2) spots represent > 10 to 25 percent of the 

stand, or, (3) the manager is seeking opportunities to change 

species or genetic composition. If managers choose to not 

combine spots, they should reenter the key at the second 

“8” alternative and proceed to select a new prescription. If 

managers choose to combine spots, they should reenter the 

key at the first “4” alternative and proceed to select a new 

prescription.

Prescription G—When all spots are too small to be 

salvaged or the stand is scheduled for a regeneration 

harvest in 1 to 2 years, opportunities to regenerate the spot 

are absent. The manager should proceed with planned 

management of the surrounding stand. The manager may 

consider using nonregenerated spots as opportunities to 

provide wildlife habitat or food plots. 

Prescription H—The manager should plan a regeneration 

cut for this stand. In this case, much of the pine component 

has been lost and the remaining stand is of low value. 

A regeneration harvest should be delayed if the stand is 

soon likely to pass from one product class to another (e.g., 

pulpwood to sawtimber) or otherwise increase in value 

or merchantability. As the desirable species is lacking, 

artificial regeneration is indicated. The manager should plan 

for control of undesirable species at the time of harvest or 

as part of the site preparation or vegetation management 

practices. 

Prescription I—In this case, spots should be regenerated. 

The stand is young enough that pine regrowth in spots can 

provide timber products by the time the surrounding stand is 

harvested. This is relevant to managers who want ultimately 

to regenerate the stand by natural regeneration. Although 

trees in spots will probably be too young to be abundant 

seed producers when the stand is harvested, and this should 

be taken into account, they will likely provide some seed 

to assist with regeneration. This option is also valuable to 

managers that want to increase the component of an underrepresented species in the stand. Spots may be regenerated 

by planting or seeding, either of which should commence 

no nearer than 30 feet from the gap edge. If seedlings are 

planted, planting density should be on the order of one-half 

the typical planting density (trees per acre) for the species 

9
and landowner. Regardless of whether spots are seeded or 

planted, care must be taken to protect regeneration when 

silvicultural practices are carried out in the surrounding 

stand. If possible, regenerated spots should be thinned 

early, frequently, and heavily to allow the trees to catch up 

in diameter to the surrounding stand and to facilitate the 

development of good crowns for seed-bearing if the stand 

will be naturally regenerated. If neither species conversion 

nor natural regeneration is planned, the manager may 

consider doing nothing in these spots.

Prescription J—In this situation, the manager has 

basically chosen to manage a hardwood-dominated stand. 

No regeneration of pine is desired. Spots will naturally 

regenerate to some mixture of hardwood and pine.

Prescription K—This situation represents an opportunity 

for conversion to uneven-aged management. If the manager 

makes this choice, the key should be reentered with that 

objective in mind, and then the manager should choose the 

first “1” choice and proceed to a new prescription. If 25 

percent or more of the stand is in spots, the manager should 

reconsider his or her criterion for minimum stand size. If 

practical, treat the spots (or coalesced groups of spots) as a 

new stand, reenter the key selecting the first “4” choice, and 

proceed to a new prescription. 

The spots should be site-prepared, and the manager should 

protect the spots from damage by silvicultural activities 

in the surrounding stand. Pre-commercial and commercial 

thinning of the spots will likely be necessary. As the stand 

will be harvested as a whole at final rotation, thinning within 

the spots should be heavier than in comparable even-aged 

stands to allow the younger trees to catch up to the older 

trees in the surrounding stand. Even if nothing is done, the 

spots will likely seed-in naturally with loblolly or shortleaf 

pines if these species are common in the surrounding stands. 

In the absence of a seed source, seedlings may be planted 

in the spots. Planting seedlings may also be indicated when 

the manager desires to alter species or genetic composition. 

Be aware that considerable natural regeneration will occur 

within 60 feet of the gap edge. Protection of the seedlings 

and subsequent thinnings should be planned. It may be 

necessary to control competing vegetation in the spots.

Prescription L—If spots represent a significant portion of 

the stand but are relatively small, they do not represent a 

good opportunity for regeneration. On all but the harshest 

sites, some tree species will become established even if the 

manager does nothing. The stand will still provide most 

forest values at a satisfactory level. An exception to this is 

when habitat is desired for species that require old, open, 

and even-aged stands. In this case, action should be taken 

to discourage regeneration of the spots or the regeneration 

should be thinned by fire or felling. By doing this, the risk 

of future SPB infestation is reduced. If a manager arrives at 

this prescription, but seems troubled by the choice, a smaller 

threshold should be selected for minimum stand size.

Prescription M—If managers aim to maximize timber 

production of all acreage, they may choose to plant 

seedlings to regenerate spots. This might be practical if 

the following situation holds: (1) spots approach minimum 

stand size, (2) spots are accessible to existing roads, and 

(3) it is economically reasonable to regenerate the spots. 

Regarding the economy of scale issue, the manager must 

judge the minimum area that is reasonable to be contracted 

for planting, weed control, pre-commercial thinning, etc. 

To regenerate the spots, large seedlings should be planted 

30 feet or more from the gap edge at approximately half the 

density that is typically used in plantations. Care must be 

taken to protect regeneration when silvicultural practices 

are carried out in the surrounding stand. If possible, the 

regenerated spots should be thinned early, frequently, 

and heavily to allow the trees to catch up in diameter to 

the surrounding stand. Thinnings may be integrated with 

thinnings in the surrounding stand or with nearby similarly 

aged spots or stands.

SUMMARY

This paper provides a key to assist forest managers with 

regeneration decisions in overstory gaps (spots) created by 

the southern pine beetle. Spots are typically small relative 

to the overall stand, so a number of unusual economic, 

ecological, and silvicultural considerations arise for 

decisionmakers. The key’s major value is in helping to 

organize pertinent information so that an optimal course 

of action can be prescribed. In each case the key leads to 

a prescription—based on spot and stand characteristics, 

economic considerations, silvicultural principles, and land 

manager objectives—that helps determine the best course 

of action for meeting management objectives with both the 

present and future stands. 

ACKNOWLEDGMENTS

The authors thank Donald Baker (Baker Land & Timber 

Management, Inc.), Dr. Mason Carter (Retired, LSU 

School of Renewable Natural Resources), Donald Feduccia 

(Retired, Louisiana Department of Agriculture and 

Forestry), and Dr. James Meeker (USDA Forest Service, 

R8-Forest Health Protection) for their time and efforts 

toward improving this report.

10
LITERATURE CITED

Baker, J.B.; Balmer, W.E. 1983. Loblolly pine. In: Burns, R.M., 

comp. Silvicultural systems for the major forest types of the 

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Forestry. 90 p.

11

Goelz, J.C.G.; Strom, B.L.; Barnett, J.P.; and Sword Sayer, M.A. 2012. Guidelines 

for regenerating southern pine beetle spots. Gen. Tech. Rep. SRS-153. Asheville, NC: 

U.S. Department of Agriculture Forest Service, Southern Research Station. 11 p.

Southern pine forests are of exceptional commercial and ecological importance to 

the United States, and the southern pine beetle is their most serious insect pest. The 

southern pine beetle generally kills overstory pines, causing spots of tree mortality that 

are unpredictable in time and space and frequently disruptive to management activities 

and goals. The canopy gaps created may be large enough for regeneration activities to 

be considered, but the nature of southern pine beetle spots, and the residual stands of 

which they are a part, can make regeneration decisions complex. Spot size and shape, 

stand age, structure, silvicultural system, product markets, and management goals 

all are important determinants for obtaining successful regeneration of southern pine 

beetle spots. This paper provides a key to assist managers faced with the complexities 

of regenerating southern pine beetle spots in the context of the larger stand. Guidance is 

provided for the application of regeneration methods that are appropriate for particular 

management objectives, spot sizes, stands, and environmental conditions. 

Keywords: Forest management, overstory pines, regeneration, residual stands, southern 

pine beetle spots.

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