United States

Department of

Agriculture

Forest Service

Southern

Research Station

Resource Bulletin

so-195

Summary Report:

Forest Health Monitoring

in the South, 1992

John S. Vissage and William H. Hoffard
In 1990, the USDA Forest Service and the U. S. Environmental

Protection Agency launched a cooperative program, Forest Health

Monitoring, to monitor the health of the Nation’s forests. Several

indicators of forest health have been measured on permanent plots

in 14 States. Data gathered from Alabama, Georgia, and Virginia

in 1992 are summarized in this report. Simple percentage distributions of crown ratings and damage data from sample plots do

not suggest that there are any widespread problems in these

States. Only 1 percent of the sample trees has poor crowns. However, surveys show that insects and diseases continue to cause

substantial forest damage in the southern region.

January 1997

Southern Research Station

P.O. Box 2680

Asheville, North Carolina 28802
Contents

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

ON-FRAME ACTIVITIES .............................. 1

Findings ........................................... 2

FINDINGS FROM OFF-FRAME ACTIVITIES . . . . .

Fusiform Rust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Southern Pine Beetle . . . . . . . . . . . . . . . . . . . . . . . . .

Dogwood Anthracnose . . . . . . . . . . . . . . . . . . . . . .

Oak Decline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Gypsy Moth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Balsam Woolly Adelgid . . . . . . . . . . . . . . . . . . . . . . .

Other Conditions Affecting Southern Forests in 1992

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DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

APPENDIX ......................................... 13

Tables I- 18 ..................................... 14-25
Summary Report:

Forest Health Monitoring in the South, 1992

John S. V&age and William H. Hoffard

INTRODUCTION

Forests cover much of the South. They provide timber, wildlife habitat, recreation, and many other benefits. Concern about the effects of air pollution, drought,

and other anthropogenic and natural stressors has increased in the past decade. In response to these concerns,

the USDA Forest Service and the U.S. Environmental

Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) jointly sponsor the Forest

Health Monitoring (FHM) program. The State foresters

and other State and Federal agencies are key cooperators and partners in the FHM program.

The primary goal of FHM is to monitor, evaluate,

and report on the health of the forests at regional and

national scales. To accomplish this goal, FHM is organized into three monitoring activities. The first, detection monitoring, establishes baseline conditions and

detects unusual deviations or events. In detection

monitoring, selected indicators of forest health are

sampled on a network of permanent plots. This sampling is referred to as on-frame sampling. Supplemental surveys detect outbreaks of forest insects and

diseases and are referred to as off-frame surveys. The

second activity, evaluation monitoring, is triggered by

unexplained changes in forest health indicators.

Evaluation monitoring identifies cause-and-effect relationships, provides information for management

responses, and identifies additional research needs.

Intensive site ecosystem monitoring, the third activity, studies forest ecosystem processes and their effects on forest health.

Detection monitoring activity began in 1990 in six

New England States. In 1991, it began in three midAtlantic and three Southern States, and, in 1992, it

began in two Western States.

The results of detection monitoring activity in the

South in 1992 are summarized in this report. In the

first part, data from the plot network in Alabama,

Georgia, and Virginia are summarized. All values reported are simply counts or percentages of sample

observations. No statements of statistical significance

are implied. Statistical treatment of the data is discussed in the Forest Health Monitoring 1992 Annual

Statistical Summary (Forest Health Monitoring 1994).

The second part of this report is a synopsis of various

insect and disease surveys. There was a similar report for detection monitoring activities in 1991

(Bechtold and others 1992).

ON-FRAME ACTIVITIES

The FHM program uses a systematic grid developed

by EMAP to choose sample locations. This approach

is designed to provide a statistically valid sample of

all land categories. Field crews install a FHM plot

when any part of it falls in forest land. The FHM plot

is a cluster of four l/24-acre fixed-radius subplots

spaced 120 feet apart (fig. 1). Trees 5.0 inches and

larger in diameter at breast height (d.b.h.) are recorded

if they are within the 24.0-foot radius defining each

subplot. Trees with d.b.h.‘s from 1.0 through 4.9 inches

are recorded if they are in 6.8-foot radius (l/300-acre)

microplots offset 12 feet from the center of the subplots. The FHM plots sometime straddle land-use and

forest-condition classes, so subplots, microplots, and

tally trees are mapped by condition class (Conkling

and Byers 1992).

Data collection efforts in 1992 focused on the damage and visual crown rating (VCR) indicators. Data

were collected from plots with at least one live tree

1.0 inch or larger in d.b.h. in 1991.

For each tree 5.0 inches or larger in d.b.h., field

crews recorded up to three damages in order of severity.

Severity was rated on the basis of the likelihood of tree

mortality, growth loss, or introduction of damaging

agents. Field personnel recorded the location and probable cause for each damage. Only the most severe damage observed for each tree is tabulated for this report.

John S. Vissage is a forester with the Forest Inventory and Analysis Unit, Southern Research Station, U.S. Department of Agriculture,

Forest Service, Starkville, MS 39759: William H. Hoffard is an entomologist with the Forest Health Unit, U.S. Department ofAgriculture,

Forest Service, Region 8, Asheville, NC 28802.

1
Figure l.- National Forest Health Monitoring plot design (from

Conkling and Byers 19921.

The VCR variables for trees 5.0 inches in d.b.h. or

larger are live-crown ratio, crown diameter, crown

density, foliage transparency, and crown dieback. Additional information about the VCR indicator is available in Anderson and Belanger (1987), Belanger and

Anderson (1989), and Millers and others (1992).

Live-crown ratio is the proportion of total tree height

that supports live foliage that effectively contributes

to tree growth. Dead tops and dead lower branches

are excluded. This variable is associated with tree

vigor and d.b.h. growth (Millers and others 1992).

Crown diameter is the average of the width of the

tree crown at its widest point and the width of the

crown 90 degrees from the widest point. This is another indicator of tree vigor (Millers and others 1992).

Crown density is an estimate of the percentage of skylight obstructed by branches, foliage, and reproductive

structures. Anderson and Belanger (1987) found that

high crown density percentages are positively correlated

with radial growth in loblolly and shortleaf pines.

Foliage transparency is the amount of skylight visible through the live, normally foliated portion of the

crown. Dead portions of the crown are excluded as are

large gaps and holes. This rating is an indicator of the

amount of foliage in the crown.

Crown dieback is branch mortality that starts near

the terminal and proceeds toward the trunk. Usually,

dieback occurs in the upper part of the crown and is a

symptom of other problems. Branches in the lower part

of the crown that die from competition are not counted

as dieback.

2

Crown-vigor class applies only to trees from 1.0 to

4.9 inches in d.b.h. and is the only VCR datum presented for these trees. This description separates trees

in obviously good condition from those in obviously

poor condition. A tree must meet three criteria to be

classified as good. First, at least one-third of its length

must have live foliage. Second, there can be no dieback in the upper half of the crown. Third, at least 80

percent of the foliage must be undamaged. When a

tree does not qualify as good, it is rated either as average or as poor. Average and poor trees can have any

portion of their length in live foliage and can have any

amount of dieback. A tree is classified as poor when at

least 80 percent of its foliage is missing or abnormal.

A tree is classified as average when 20 to 80 percent

of its foliage is normal.

Findings

Field crews visited 349 plots in the three States,

and they measured 9,631 trees (table 1). About 24 percent of the trees were from 1.0 through 4.9 inches in

d.b.h. and occurred on the microplots. Seventy-four

percent of the trees 5.0 inches in d.b.h. and larger were

classified as overstory trees. About 49 percent of the

overstory trees were softwoods, and 51 percent, hardwoods (table 2).

Ninety-nine percent of the overstory trees had average or good crown density (table 3). Shortleaf pine,

other softwoods, and other hardwoods were the only

species groups in which more than 2 percent of the

overstory trees had poor crown density. The methods

used to estimate crown density in 1991 and 1992 differed slightly, so findings for 1991 and 1992 are not

directly comparable.

More than 99 percent of the overstory trees were

classified as having normal transparency in 1992

(table 4) as compared to 97 percent in 1991. The proportion of shortleaf pine and sweetgum in the normal

class decreased whereas proportions of trees with normal crown transparency increased slightly for other

species.

Ninety-three percent of the softwoods and 79 percent of the hardwoods had no crown dieback (table 5).

In 1991,98 percent of the softwoods and 85 percent of

the hardwoods had no dieback. The proportion of trees

with light dieback increased slightly in all species

groups except slash pine and hickories. There was little

change in the proportion of trees with moderate or

severe (21 percent or more) dieback.

Eighty-one percent of all softwoods and about 62

percent of all hardwoods had no damage in 1992 (table

6). Disease was the most common damaging agent for

softwoods, and unknown agents caused the highest

percentage of damage in hardwoods. Overall, the percentage of trees with damage decreased from 1991 to

1992, and the proportion of slash pine and maples
Table l.- Number of plots and trees measured by State, Southern Forest Health Monitoring

Region, 1992

Trees sampled

State Plots

1.0-4.9 inches

in d.b.h.

2 5.0 inches in d.b.h.

Understory Overstory Total trees

Alabama 124 850 767 1,753 3,370

Georgia 127 776 495 1,908 3,179

Virginia 98 711 603 1,768 3,082

Total 349 2,337 1,865 5,429 9,631

exhibiting damage was slightly greater in 1991 than

in 1992.

More than 90 percent of the saplings had average

or good crown vigor (table 7). There were no dramatic

shifts in crown-vigor class.

FINDINGS FROM OFF-FRAME ACTIVITIES

The off-plot Forest Health Monitoring data discussed here come from a variety of sources, including

the USDA Forest Service (Forest Health Unit and

Forest Inventory and Analysis), cooperating State

agencies, and non-Forest Service Federal agencies.

Fusiform Rust

In 1992, fusiform rust continued to be the most damaging disease of loblolly and slash pines in the South

(table 8). According to the most recent estimates, which

are based on data from Forest Inventory and Analysis

plots, almost one-third of all loblolly and slash pine

acres were infected with at least 10 percent of the

loblolly and slash pines having a potentially lethal

canker (on or within 12 inches of the stem).

Southern Pine Beetle

Southern pine beetle activity expanded markedly

in 1992, with pockets of outbreaks scattered across

Table 2.- Number of trees sampled by selected species group, tree size, and crown position, Southern Forest Health Monitoring Region, 1992

Species group

1.0-4.9 inches

in d.b.h.

2 5.0 inches in d.b.h.

Understory Overstory

Softwoods

Longleaf pine

Slash pine

Shortleaf pine

Loblolly pine

Virginia pine

Other softwoods

______________________________________ Number _________________ ____________________

7 12 91

25 17 284

28 58 213

298 131 1,535

29 69 365

39 55 140

All softwoods 426 342 2,628

4

Hardwoods

White oaks

Red oaks

Maples

Sweetgum

Yellow-poplar

Blackgum

Hickories

Other hardwoods

90 223 570

323 196 639

250 210 246

271 182 349

73 61 303

164 150 182

107 121 197

633 380 315

All hardwoods 1,911 1,523 2,801

All species 2,337 1,865 5,429




crease since 1991. Table 10 shows the increase in cumulative acreage affected by dogwood anthracnose

from 1988 to 1992. As of 1992, more than 12 million

acres have been affected by this disease.

The disease continued to be more severe above 3,000

feet where most of the dogwoods had died. At elevations between 2,000 and 3,000 feet, dogwoods in the

shade were infested and dying. At elevations below

2,000 feet, the damage was most severe in cool, wet,

shaded areas. It is too early to predict future losses.

Loss of the dogwood is of major concern because of

esthetic reasons and because the species is an important source of wildlife food and cover.

Figure 4 shows the locations of counties in which

dogwood anthracnose infections were confirmed

though laboratory diagnosis.

Oak Decline

Oak decline is a slow-acting disease syndrome involving interactions of several predisposing factors

such as climate, microsite, and tree age, stress facTable 9.- Number of southern pine beetle spots by year

State

Alabama

Arkansas

Georgia

Louisiana

Mississippi

North Carolina

South Carolina

Tennessee

Texas

Virginia

Total

1991 1992

4,605 6,404

20 625

4,303 5,640

4,509 8,923

5,628 4,352

475 1,828

1,697 1,518

4 428

2,755 5,500

170 3

24,166 38,346

tors such as drought and insect defoliation, and contributions by secondary organisms such as two-lined

chestnut borer and Armillaria root disease. Mature

overstory trees on poor sites are most commonly affected. Oak decline continued to be a problem in areas where it was a problem in 1991. Figures 5 and 6

show survey sites on which oak decline was confirmed

for upland and lowland oaks. The most serious impact was in States with mountainous terrain, probably because such terrain is associated with water

stress and adverse microsite conditions. Information

about oak decline in Kentucky was not available.

Figure 3.-Counties with southern pine beetle outbreak, 1992.
Table lO.-Cumulative acreage affected by dogwood anthracnose, 1988-1992

State 1988 1989 1990 1991 1992

---~~~~~~________________~~~~_~_______________ acres _____________________________________________

Alabama* -_

Georgia 153,875

Kentucky* _ _

North Carolina 123,507

South Carolina 158,292

Tennessee 253,172

Virginia 13,433

*Data not available until 1992.

-_ __ _ _ 199,144

369,415 832,922 1,059,661 1,265,688

_ _ _ _ _ _ 1,436,830

531,730 1,519,769 1,873,725 1,896,199

295,675 737,177 804,559 790,479

655,962 1,313,190 2,043,899 2,918,166

346,473 1,205,054 3,610,279 4,187,352

Figure 4.-Counties of the southeastern United States with confirmed dogwood anthracnose

infections, 1992.

Figure 7. -Areas defoliated hy gypsy moth, Virginia, 1992.

Gypsy Moth

Gypsy moth continued its steady spread to the south

and west, Federal and State records show that gypsy

moth defoliated 616,300 acres in 1991 and 748,000

acres in 1992. Forty percent of all defoliation occurred

on Federal lands, and one of every four defoliated acres

was in the George Washington National Forest in

northern Virginia.

Small, isolated infestations were also reported from

North Carolina, Tennessee, Arkansas, and Georgia.

Figure 7 shows the location of defoliated areas in

Virginia. Figure 8 shows percentages of acreage defoliated in George Washington National Forest,

Shenandoah National Park, and all other ownerships.

Balsam Woolly Adelgid

Since its first appearance in the southern Appalachians in the 1950’s, the balsam woolly adelgid (BWA)

has spread and is now found in virtually every sizable

concentration of spruce-fir forest type in the region.

The BWA slowly kills firs, usually within about 15

years. As a result, the age classes for Fraser fir are

reduced, stands are smaller than normal, and numbers of red spruce, the other principal component of

the spruce-fir forest type, are disproportionately large.

The BWA continues to be a serious concern, particularly because of the damage it does in scenic and recreational areas such as those along the Blue Ridge

Parkway. Figure 9 shows the major concentrations of

Fraser fir in the southern Appalachian Mountains.

Other Conditions Affecting Southern Forests

in 1992

The fall cankerworm defoliated 85,000 acres in localized areas in North Carolina and southwest Virginia.

Forest, tent caterpillar defoliated more than 300,000

acres of water tupelo in Louisiana in the spring. Widespread light defoliation on blackgum was also reported

in North Carolina, Virginia, and South Carolina.

Shenandoah

12.8 %

NP

Figure B.-Percent ofgypsy moth defoliation by Landowner land

manager jurisdiction, Virginia, 1992.

11
Kentmky

Virginia

North Carolina

Figure 9. -Fraser fir concentrations in the southern Appalachians.

Locust leafminer, normally a relatively inconsequential insect, caused widespread damage in the southern

Appalachians, especially in western North Carolina and

eastern Tennessee.

Butternut canker continued to spread in the South.

The disease had eliminated 77 percent of the butternut throughout the region by 1992.

Anthracnose incidence (various species) was high

in 1992 because of unusually wet spring conditions.

Oak wilt intensified in the South in 1992. Particularly hard hit was Texas, where infections occurred in

46 counties. Gypsy moth defoliations complicated oak

wilt surveys in Virginia.

In Florida, ocean rise continued to cause widespread

mortality of coastal cabbage palms (see 1991 report).

DISCUSSION

The crowns of the great majority of sampled trees

appeared normal. Only 1 percent of the sample trees

had poor crown density, severe foliage transparency,

or moderate to severe crown dieback. These data do

not suggest any widespread changes in the crowns

since 1991.

On the other hand, the proportion of damaged trees

decreased from 37 percent in 1991 to 29 percent in

1992. Much of the decrease was in the hardwood species (52 percent exhibited damage in 1991 and 38 percent exhibited damage in 1992). In 1991, 11.8 percent

of the hardwoods had weather damage, but only 1.1

percent exhibited such damage in 1992. Some damaged trees may have died between the two assessments. Also, weather damage increases the susceptibility

of trees to insects and diseases, and these may have

supplanted weather as the most severe damage in

some instances. It is not known whether the amounts

of damage or the observed changes are unusual.

The regional patterns also hold for the States where

on-frame work was done (Appendix, tables 1-18). Poor

crown ratings were assigned to only a very small percentage of overstory trees in each State. The proportion of damaged trees decreased in all States. The

incidence of damage followed the same spatial pattern described by Bechtold and others (1992). The proportion of trees damaged in Virginia was 42 percent,

compared to 27 percent in Georgia and 18 percent in

Alabama.

12
LITERATURE CITED

Anderson, R.L.; Belanger, R.P. 1987. A crown rating

method for assessing tree vigor of loblolly and shortleaf pines. In: Phillips, D.R., camp. Proceedings of

the fourth biennial southern silvicultural research

conference; 1986 November 4-6; Atlanta, GA. Gen.

Tech. Rep. SE-42. Asheville, NC: U.S. Department

of Agriculture, Forest Service, Southeastern Forest

Experiment Station: 538-543.

Bechtold, W.A.; Hoffard, W.H.; Anderson, R.L. 1992.

Summary report: forest health monitoring in the

South, 1991. Gen. Tech. Rep. SE-81. Asheville, NC:

U.S. Department of Agriculture, Forest Service,

Southeastern Forest Experiment Station. 40 p.

Belanger, R.P.; Anderson, R.L. 1989. A guide for assessing crown densities of loblolly and shortleaf

pines. Res. Note SE-352. Asheville, NC: U.S. Department ofAgriculture, Forest Service, Southeastern Forest Experiment Station. 2 p.

Conkling, B.L.; Byers, G.E. 1992. Forest health monitoring field methods guide. Las Vegas, NV: U.S.

Enviromental Protection Agency; internal report.

Forest Health Monitoring. 1994. Forest health monitoring 1992 annual statistical summary. EPA 620/

R-94/010. Washington, DC: U.S. Environmental

Protection Agency. 43 p.

Millers, Imants;Anderson, Robert; Burkman, William;

Hoffard, William. 1992. Crown condition rating

guide. Radnor, PA: U.S. Department ofAgriculture,

Forest Service, Northeastern Area, Forest Health

Protection. 26 p.

13

APPENDIX

15












Vissage, John S.; Hoffard, William H. 1997. Summary report: forest health

monitoring in the South, 1992. Resour. Bull. SO-195. Asheville, NC:

U.S. Department of Agriculture, Forest Service, Southern Research

Station. 27 p.

In 1990, the U.S. Department of Agriculture, Forest Service and the U.S.

Environmental Protection Agency launched a cooperative program, Forest

Health Monitoring, to monitor the health of the Nation’s forests. Several

indicators of forest health have been measured on permanent plots in 14

States. Data gathered from Alabama, Georgia, and Virginia in 1992 are

summarized in this report. Simple percentage distributions of crown

ratings and damage data from sample plots do not suggest any widespread

problems in these States. Crown ratings were poor for only 1 percent of

the sample trees. A synopsis of forest insect and disease surveys in the

southern region shows that these pests continue to cause substantial

damage.

Keywords: Detection monitoring, forest damage assessment, visual crown

ratings.
The Forest Service, U.S. Department of

Agriculture, is dedicated to the principle of multiple

use management of the Nation’s forest resources

for sustained yields of wood, water, forage, wildlife, and

recreation. Through forestry research, cooperation with the States

and private forest owners, and management of the National Forests

and National Grasslands, it strives-as directed by Congress-to

provide increasingly greater service to a growing Nation.

The United States Department of Agriculture (USDA) prohibits

discrimination in its programs on the basis of race, color, national

origin, sex, religion, age, disability, political beliefs, and marital or

familial status. (Not all prohibited bases apply to all programs).

Persons with disabilities who require alternative means for

communication of program information (braille, large print,

audiotape, etc.) should contact the USDA Office of

Communications at (202) 720-588 1. To file a complaint, write the

Secretary of Agriculture, U.S. Department of Agriculture,

Washington, DC 20250, or call I-800-245-6340. USDA is an

equal employment opportunity employer.