United States

Department of

Agriculture

Forest Service

Southern

Research Station

Resource Bulletin

SRS-54

February 1994 Ice Storm: Forest

Resource Damage Assessment in

Northern Mississippi

Dennis M. Jacobs
September 2000

Southern Research Station

P.O. Box 2680

Asheville, NC 28802

Cover photo—Winter-storm damage to a loblolly-shortleaf pine research

watershed located on the Holly Springs National Forest in north Mississippi.

Photo taken two weeks after the storm. Photo courtesy of the hydrology research

unit in Oxford, MS.
February 1994 Ice Storm: Forest

Resource Damage Assessment

in Northern Mississippi

Dennis M. Jacobs, Research Forester

Forest Inventory and Analysis

Starkville, MS
iii

Contents

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

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Methods and Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Airborne Video Mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Airborne Video System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Video Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Damage Interpretation Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Mapping and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

a All tables in this report are available in Microsoft® Excel workbook files. Upon request, these files will be supplied

on 31⁄2-inch diskettes.

 The use of trade or firm names in this publication is for reader information and does not imply endorsement by the

U.S. Department of Agriculture of any product or service.

 Page
1

Abstract

During February 8–11, 1994, a severe winter storm moved from Texas

and Oklahoma to the mid-Atlantic depositing in northern Mississippi a

major ice accumulation of 3 to 6 inches. An assessment of forest resource

damage was initiated immediately after the storm by performing an

airborne video mission to acquire aerial imagery linked to global

positioning coordinates. Interpretation of the aerial video imagery

generated data that were used to map zones of similar damage severity.

The Geographic Information System map data were linked with recent

State forest resource inventory data to provide estimates of forest resource

damage. There were 2.1 million acres of forest land within the

3.7-million-acre study area in northeast Mississippi. Less than 1 percent

of the forest land remained untouched by some degree of damage. Net

loss to live-tree volume, due to probable mortality, amounted to 16.5

percent of hardwoods and 15.3 percent of softwoods. The majority of

volume loss occurred in areas that received about 25 percent mortality to

the forest resource.

Keywords: Aerial reconnaissance, airborne video system, GIS, GPS, ice

storm damage, isozone, Mississippi.

Introduction

During the late hours of February 8, 1994, an Arctic cold

front moved southward into a developing moist weather

system. While snow developed in the northern areas, sleet,

snow, and freezing rain began to fall in east Texas and

Louisiana. The storm system quickly developed heavy

precipitation and was moved eastward by cold Arctic air to

as far as Washington, DC. It dissipated over the Atlantic

seaboard on February 11.

This was the worst ice storm to occur in Mississippi since

January 1951 (NOAA 1994). Precipitation totaling as

much as 8 inches moved across northern Mississippi on

February 9, bringing ice accumulations of 3 to 6 inches

over much of the area. Ice accumulation on power lines

and trees caused some areas of the State to be without

electrical power for more than a month. Timber damage

was estimated at $1.3 billion, although Mississippi’s timber

harvest (most valuable agricultural commodity in Mississippi) continued apace—$1.02 billion in 1993, $1.07

billion in 1994, and $1.10 billion in 1995 (Daniels 1995,

1996).

The Mississippi Forestry Commission conducted aerial

reconnaissance of the area immediately to determine the

extent of storm damage. Portions of 32 counties had been

affected. The forestry commission then asked the U.S.

Department of Agriculture, Forest Service, Southern

Research Station, Forest Inventory and Analysis Research

Work Unit (FIA) in Starkville, MS, to determine the extent

of damage to forest resources. The storm deposited a large

amount of ice on the forest canopy, resulting in massive

canopy destruction and a significant loss of timber volume.

The forestry commission needed to develop fire-hazard

mitigation plans for the new fiscal year almost immediately.

A determination of the heavy fuel load created by canopy

damage was therefore necessary. The timber damage also

appeared to have compromised the integrity of the FIA

1994 forest inventory of northern Mississippi, which was

completed in the fall of 1993 (Faulkner and others 1993).

Our objectives were to generate damage-severity maps of

the area and combine the damage estimates with recent

State survey data to provide estimates of affected forest

area and resource damage.

Our study was limited to the more heavily forested

northeast Mississippi region, covering portions of 18

counties; we did not assess damaged forest area in the

Mississippi River Alluvial Plain known as the Delta, where

timber is sparse.

Background

Several catastrophic natural events have occurred in

Mississippi over the past several decades. We used various

reconnaissance techniques to assess damage to the area’s

natural resources. One such catastrophic event occurred

on August 17, 1969, when Hurricane Camille moved

inland from the Gulf of Mexico, resulting in damage

totaling 290 million cubic feet of growing stock throughout 15 counties in southern Mississippi (Van Hooser and

Hedlund 1969). Because we had completed a field inventory of the affected area in 1967, we needed to assess the

damage and update the field inventory data. We used aerial

reconnaissance to delineate areas of damage and determine

where ground measurements should be taken. We then

developed a plan that included a sampling grid with plot

locations spaced at a 4-mile interval.

Procedures we developed after Hurricane Hugo struck

South Carolina on September 21, 1989, were significantly

different from those we followed to conduct the Hurricane

Camille assessment. In assessing damage from Hurricane

Hugo (Sheffield and Thompson 1992), we used permanent

FIA plots in 23 South Carolina counties and corresponding

data from the 1986 field survey (Tansey and Hutchins

1988).

We developed a two-phase sampling plan that allows quick

assessment of catastrophic events that affect the integrity

of forest inventories. First, we fly a video mission to gather

a sufficient sample of aerial imagery. These video sample

data and corresponding geographic coordinates are used to

determine damage severity and to map the damage using a

Geographic Information System (GIS). Second, we

combine assessment data with the most recent data from

the State field inventory for the area. This technique

provides an estimate of the forest resources damage, as

well as the area of forest land and forest-type groups that
2

are affected by the event. The immediate georeferencing

techniques of Global Positioning System (GPS) and cloud

cover situations play an important role in the decision to

use airborne video in each large-scale damage assessment.

Aerial reconnaissance is usually performed to quickly

assess the extent of damage due to catastrophic events.

The portability of airborne videography equipment

provides for acquisition of aerial imagery when performing

the next phase of the damage assessment. The FIA uses

airborne videography and GPS data to assess catastrophic

events occurring in southern forests. The aerial video

imagery is used to delineate areas of similar forest damage.

Such damage zones are then linked to the FIA forest

resource inventory groundplot data for estimates of

resource damage.

Damage assessment methodologies using airborne video

techniques were developed within days of Hurricane

Andrew’s landfall in southern Louisiana on August 25,

1992 (Jacobs and Eggen-McIntosh 1993). The Louisiana

Office of Forestry made an immediate aerial reconnaissance of the hurricane-damaged area and requested that

the FIA in Starkville, MS, perform a forest damage assessment. Three days after the storm had passed, we flew

GPS-referenced airborne video transects over the affected

area, totaling over 600 air miles of flight lines. According

to the 1991 State inventory (Vissage and others 1992), the

hurricane study area encompassed 4.2 million acres and

contained 1.8 million acres of timberland. Most forest

lands in the study area were in the Atchafalaya River

Basin, which included predominantly hardwoods of the

oak-gum-cypress forest type. Approximately 1.1 million

acres of timberland received some degree of damage to

merchantable tree volume.

We modified the techniques developed for our study of

Hurricane Andrew and applied them to our analysis of the

Mississippi ice storm study area. Because there was

virtually no pine component in the hurricane study area,

we had to distinguish ice storm damage for the pine and

hardwood components separately. Visually, the damage

processes of the two components differed during the

deciduous winter season: hardwoods appeared somewhat

less affected than pine.

In a study of three Mississippi watersheds that received

damage, Halverson and Guldin (1995) determined that

pines received more stem breakage than hardwoods. Those

watersheds received 100 percent inventories before and

after the ice storm. Their results showed that 72 percent of

pines sustained stem breakage, whereas hardwoods sustained only 15 percent. The overall damage assessment

indicated that 88 percent of pines were affected with some

type of ice damage, but only 37 percent of hardwoods.

Methods and Procedures

Study Area

Although forest damage was severe and widespread from

the Mississippi River to the Alabama State line, our study

area included only the more heavily forested region in the

northeast corner of the State. Land on the Delta in northwest Mississippi is mostly agricultural; there are few areas

of forest land. Because of the difficulty in following airborne video transect procedures on such scattered tracts of

forest land, we limited our study area to 3.7 million acres

in the northeastern portion of the State. According to 1994

inventory data, 2.1 million acres of forest land were within

the ice storm study area. Although the Hurricane Andrew

study area was 4.2 million acres, it included less forest

land.

The dominant oak-hickory forest type is found on about

half of the timberland in the study area. Loblolly-shortleaf

pine, oak-pine, and oak-gum-cypress forest types are

found on most of the rest. Principal tree species for northeastern Mississippi include oaks, hickories, shortleaf pine,

loblolly pine, redcedars, tupelo-gums, sweetgum, baldcypress, elms, red maple, yellow-poplar, ashes, and

sugarberry.

Airborne Video Mission

Airborne video missions are designed somewhat differently

from aerial photography missions. Aerial photography

missions are designed to produce total coverage of a study

area, whereas aerial videography is designed as a sampling

tool. Video flight lines are flown on a metric grid that will

provide a sufficient number of samples for the area

studied, as well as a continuous video transect sample. For

large study areas, video flight lines may be several kilometers apart. In a typical mission, recording a 100-meter

swath along the flight line will produce images with high

enough resolution to identify details within the canopy

structure. A single video frame at this resolution will cover

0.75 hectare. If a wider swath is desired for broader areal

ground coverage, and visualization of individual tree

crowns is the desired component rather than canopy

structure, the swath can be increased to 250 meters by

flying at a higher altitude. This wider swath will provide a

single video image of approximately 5 hectares.

The Mississippi Forestry Commission provided a State

plane and pilot, we mounted the GPS-video system. Our

plans were to acquire imagery on north-south airborne

video transects nearly perpendicular to the path and isoline

severity of the ice storm. We spaced flight lines at 9-mile

intervals, as closely oriented to the 3- by 3-mile FIA plot

location grid as possible.
3

Flying at altitude 660 meters and using the maximum

zoom (66 millimeters) for the focal length of the camera

lens, provided a video footprint of 88 by 66 meters (0.6

hectare = 1.5 acres) for each sample location. This area

coverage for the video image was slightly larger than the

ground area covered by a forest inventory field plot (0.4

hectare = 1 acre). The combination of flying altitude and

focal length produced a ground-to-image resolution of

13.75 centimeters per picture element (5.4 inches per

pixel).

Airborne Video System

The FIA airborne video system (Jacobs and Evans 1996)

allows us to collect vertical aerial video imagery of forest

lands when rapid response is necessary or preferred. The

equipment is easily transportable and can be installed in an

aircraft on the same day it is used. The system includes

four main parts: (1) video camera head, (2) color video

monitor, (3) GPS receiver, and (4) video recording unit

with a small graphics computer board that generates text

onto the video image, such as GPS coordinates, altitude,

date, and time.

Video Sampling

With the 9-mile spacing of flight lines, we subsampled the

vertical aerial video imagery along each flight line at a

1-mile interval. This provided 1- by 9-mile spacing and a

1-to-1 ratio to the 3- by 3-mile spacing of permanent FIA

field plots.

We modified techniques developed during the assessment

of forest damage from Hurricane Andrew to assess

damage from the ice storm. Our sample spacing was

slightly different but provides a sampling intensity equal to

the number of forest video samples in the Hurricane

Andrew study area (Jacobs and Eggen-McIntosh 1993). In

the hurricane study, we used a 0.5-mile spacing along the

flight line, captured forest and nonforest video frames, and

interpreted the forest video frames for damage severity.

A tabular list of latitude coordinates was generated for

1-mile increments (0.8689762 minute of latitude). Coordinates were cross-referenced with GPS coordinates on each

video frame, and location samples were selected accordingly. We might have selected coordinates at even increments of 1 nautical mile (1 minute of latitude), but such

spacing would not have represented the 3- by 3-mile

spacing of the FIA plots. Nonetheless, it became evident

that choice of spacing may be somewhat irrelevant.

Our objective was to determine damage to forest

resources. When we found a video sample location to be

nonforest, we used the nearest forest video frame along

the video transect as the sample location. Consequently,

the number of sample locations was intensified beyond the

1-to-1 ratio; there were 579 forest video sample locations

but only 344 FIA forest plots within the study area. This

modified sample selection criterion provided forest

samples within sparsely forested areas, although segments

of some video transects showed no forest for up to 8 miles

of flight line (fig. 1).

Encoded onto the video imagery in flight, GPS coordinates were used to label each of the 579 video frames

during analog-to-digital conversion. For example,

34d21.0823n89d19.1079w is the digital file name of

the video frame recorded at lat. 34°21.0823’ N,

long. 89°19.1079’ W. Although GPS coordinate precision

as written may suggest 15- to 18-centimeter accuracy, the

single-fix position of each video frame is only accurate to

the GPS standard of 100 meters 95 percent of the time.

This accuracy value is further eroded by the orientation of

the aircraft.

Damage Interpretation Procedures

The file names are easily input, as geographic coordinates,

to a GIS map file in order to create a point cover of the

video sample point locations and associated damagecondition attributes. These attributes and other assessment

variables listed in the following tabulation were used to

interpret aerial video imagery at each sample location.

A.Hardwood percent and midpoint value (percent)

1. 0–25 12.5

2. 25–70 37.5

3. 50–75 62.5

4. 75–100 87.5

B. Hardwood or pine merchantability

0. Premerchantable

1. Merchantable

C.Hardwood or pine volume damage (bole mortality)

0. No visible damage

1. 1 to 33 percent of timber volume downed (light)

2. 34 to 67 percent of timber volume downed (moderate)

3. Over 67 percent of timber volume downed (severe)

D.Live tree damage (form/crown damage)

0. No visible damage

1. Less than 50 percent of canopy damaged, or basal area

affected by other form damage

2. More than 50 percent canopy damage
4

Each digital video image was interpreted for percentage of

hardwood versus percentage of pine on a merchantable

basal-area basis and grouped into one of four categories.

Damage conditions were interpreted separately for each

species group because pines are presumed to be more

susceptible to ice damage than hardwoods. We used the

merchantability variable to determine how many video

sample locations had no mature timber in either species

category. Canopy damage values could have been applied

to the premerchantable species group on these video plots

to determine probable stem mortality.

Because visual interpretation procedures can be considered

highly subjective, we limited the damage categories to a

tertiary breakdown for volume damage and a binary

breakdown for canopy damage. Likewise, we continuously

cross-referenced damage interpretation to other image

samples to provide continuity across the study area.

We applied volume damage (bole mortality), indicating

probable tree death, to merchantable timber only. In the

final phase of the study, we applied these damage values to

Figure 1—Study area of the February 1994 ice storm in northern Mississippi. Forested video sample locations and FIA ground plots are shown.

FIA volume and basal-area data. Live-tree damage was

interpreted for the bole and crown. The crown damage

variable indicated tree-form damage in live trees.

Mapping and Analysis

Geographic coordinates of the video samples and corresponding damage values were used to contour isolines for

each forest type by similar forest damage. Figure 2 portrays the damage zones for hardwood volume and figure 3

for pine volume damage. Percent damage is represented by

six values: 1 = 0 to 16, 2 = 17 to 33, 3 = 34 to 50, 4 = 51

to 66, 5 = 67 to 83, and 6 = 84 to 100. Figure 4 portrays

total volume damage associated with the ice storm.

Damage zones 5 and 6 were nonexistent, because bole

damage of such severity occurred in isolated patches

throughout the study area, and the damage was not broad

enough to produce a distinct area of severe damage.

In aggregate, the mapping techniques (figs. 2, 3) depict

widespread light-to-moderate damage throughout the

study area for the hardwood and pine timber. The additive

Hernando

Tupelo

Oxford

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

Airborne video sample

FIA forest plot

Study area boundary

County boundary

State boundary
5

Figure 2—Hardwood volume damage of the February 1994 ice storm in northern Mississippi.

Figure 3—Softwood volume damage of the February 1994 ice storm in northern Mississippi.

2 2

3 3 4

3

1

1

2

2

2

2

3

1

2

2

Holly Springs

Oxford

Tupelo

Booneville

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

 0− 16 percent

 17− 33 percent

 34− 50 percent

 51− 66 percent

1

2

3

4

FIA forest plot

Study area isolines

County boundary

State boundary

 0–16 percent

17–33 percent

34–50 percent

51–66 percent

FIA forest plot

Study area isolines

State boundary

County boundary

1

2

2

2

4

1

3

2 2

1

2

1

3

3

1

Holly Springs

Oxford

Tupelo

Booneville

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

 0− 16 percent

 17− 33 percent

 34− 50 percent

 51− 66 percent

1

2

3

4

FIA forest plot

Study area isolines

County boundary

State boundary

 0–16 percent

17–33 percent

34–50 percent

51–66 percent

FIA forest plot

Study area isolines

State boundary

County boundary
6

effect of the damage shows up in figure 4 where isozone 2

covers a large segment of the study area and isozones 3

and 4 show collective hot spots of timber damage. At the

edge of the Delta in isozone 4, timber damage is representative of areas throughout the Delta region. The storm's

widespread damage explains why many houses were

without electricity for up to 1 month after the storm.

Table 1 provides a breakdown of the video records by

number of samples in each isozone. This dot-count

method shows that the study area’s hardwoods were

69 percent and pine 31 percent of the total damage,

respectively.

Using the percent-hardwood midpoint variable, we

developed a means of portraying the portion of timberland

associated with hardwoods in each of four isozones

(fig. 5). Comparably, FIA data show 71.1 percent basal

area hardwood within the study area. Using mid-point

percent values for each isozone in the GIS map coverage,

we found that 70.4 percent of the timberland area was in

hardwood (table 2). By comparison, Faulkner and others

(1993) showed that unit 2 in north Mississippi contained

71 percent of the basal area in hardwood.

In figure 6 we used the percent-hardwood variable to

portray pine associations. If damage had been uniform

throughout the study area, figure 6 could have been used

to identify areas receiving the heaviest damage because

pine retains foliage during the winter season.

Figure 4—Aggregate volume damage of the February 1994 ice storm in northern Mississippi.

1

1

3

4 3

1 1

3

1

3

2

1

2

3

1 3

3

1 3

1

3

1

Holly Springs

Booneville

Oxford

Tupelo

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

 0− 16 percent

 17− 33 percent

 34− 50 percent

 51− 66 percent

1

2

3

4

FIA forest plot

Study area isolines

County boundary

State boundary

 0–16 percent

17–33 percent

34–50 percent

51–66 percent

FIA forest plot

Study area isolines

State boundary

County boundary

Table 1—Number of video samples by percent–hardwood

assessment variable, February 1994 ice storm, northern

Mississippi 

Assessment

variable Hardwoodb Pinec

1 12.5 59 10.2 1.3 8.9

2 37.5 68 11.7 4.4 7.3

3 62.5 117 20.2 12.6 7.6

4 87.5 335 57.9 50.6 7.2

 Total 579 100.0 68.9 31.1

a

Divide video samples by 579 to obtain percent of total. b

Multiply percent of total by variable midpoint to obtain hardwood percent. c

Multiply percent of total by (100 - variable midpoint) to obtain pine percent.

Data may not add to totals due to rounding.

Percent

Video

Percent

Percent

 of totala

Variable

midpoint samples

 No.
7

Figure 5—Proportion of timberland associated with hardwoods—derived from airborne video imagery.

4

4

3

4

2

3 2

2

2

4

2

4

3

3

4

2

2

2

3

2

2 4 4

Oxford

Tupelo

Holly Springs

Booneville

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

 0− 25 percent

 26− 50 percent

 51− 75 percent

 76− 100 percent

1

2

3

4

Study area isolines

County boundary

State boundary

Table 2—Timberland area associated with hardwood and pine

isozones, February 1994 ice storm, northern Mississippia b

Hardwood Isozone Percent

 isozone midpoint of total Pine

1 12.5 0.0 0.0 0.0 0.0 87.5 4

2 37.5 2.9 282.0 7.7 4.8 62.5 3

3 62.5 33.1 1,936.0 52.9 19.8 37.5 2

4 87.5 34.4 1,441.0 39.4 4.9 12.5 1

 Total 70.4 3,660.0 100.0 29.6

a Pine isozones and midpoint percents are an inverse of hardwood.

b Multiply midpoint percent by percent of total area to obtain hardwood and pine 

percents of timberland area.

Data may not add to totals due to rounding.

Hardwood

midpoint

Isozone

Hardwood

Total area Pine

Pine

isozone

Isozone

area 

- - - Percent - - - - - Percent - - Thousand acres
8

Figure 6—Proportion of timberland associated with softwoods—derived from airborne video imagery.

The GIS coverage for each hardwood and pine damage

map (figs. 2, 3) identified FIA field inventory plots located

within each damage component isozone. As a cross reference, video point data are summarized by damage class

and damage zone for hardwood (table 3) and pine (table 4).

The study area includes 3,660,000 acres, 57 percent of

which is in timberland (2,113,500 acres). Volume and area

data from the latest FIA State survey (Faulkner and others

1993, Hartsell and London 1995) are correlated for the

field plots that fall within each isozone. Figures 2 and 3

3

2

2

1

2

1

1

3

1

3

3 3

3

1

3

3

2

3

3 1 1

1

2

Oxford

Tupelo

Holly Springs

Booneville

10 0 10 20 30 40 50

Kilometers

10 0 10 20 30

Miles

 0− 24 percent

 25− 49 percent

 50− 74 percent

 75− 100 percent

1

2

3

4

Study area isolines

County boundary

State boundary

Table 3—Number of video samples by hardwood damage interpretation 

and zone, February 1994 ice storm, northern Mississippi 

Damage

zone Total

1 (Light) 116 228 3 0 347 

2 (Light) 21 151 42 3 217 

3 (Moderate) 0 3 8 1 12 

4 (Moderate) 0 1 0 2 3 

5 (Severe)a 0 0 0 0 0 

6 (Severe)a 0 0 0 0 0 

 Total 137 383 53 6 579 

a Damage zones 5 and 6 are nonexistent because the isolated patches of severe damage were

not broad enough to produce isozones.

Number of samples

0 percent 1–33 percent 34–66 percent 67–100 percent

Video frame damage classification

No damage Light Moderate Severe
9

correspond with table 5, which shows the breakdown of

timberland area within each damage zone for the two

maps.

Timberland areas for forest-type groups are derived from

the FIA database and shown in tables 6 and 7. Damage

values were determined separately for the hardwood and

softwood species groups to provide different isolines and

isozones for the two maps (figs. 2 and 3). Hence, we

applied damage values for the hardwood damage isozones

only to hardwood FIA data; the loblolly-shortleaf pine

type is not shown in the hardwood table (table 6). Likewise, hardwood types are not shown in table 7 for the pine

forest types.

We applied the midpoint damage values for each of the six

isozones to FIA survey volume data to determine the net

volume of live trees before and after the storm (table 8).

Table 4—Number of video samples by pine damage interpretation 

and zone, February 1994 ice storm, northern Mississippi 

Damage

zone

1 (Light) 117 180 2 0 299 

2 (Light) 36 162 53 10 261 

3 (Moderate) 1 5 8 1 15 

4 (Moderate) 0 1 1 2 4 

5 (Severe)a 0 0 0 0 0 

6 (Severe)a 0 0 0 0 0 

 Total 154 348 64 13 579 

a Damage zones 5 and 6 are nonexistent because the isolated patches of severe damage were

not broad enough to produce isozones.

Number of samples

Total

Video frame damage classification

No damage Light Moderate Severe

0 percent 1–33 percent 34–66 percent 67–100 percent

Table 5—Area by damage zone, February 1994 

ice storm, northern Mississippi

Damage

zone Isozone 

1 2,072 1,197.0 1,839 1,008.0

2 1,495 889.0 1,694 1,059.8

3 76 27.5 111 36.5

4 17 0.0 16 9.2

5 0 0.0 0 0.0

6 0 0.0 0 0.0

 Total 3,660 2,113.5 3,660 2,113.5

Timberland

Hardwood map Pine map

Thousand acres

Timberland Isozone

Table 7—Area of timberland by pine damage

zone and forest type, February 1994, ice storm,

northern Mississippi 

Damage

zone Planted

1 1,008.0 157.3 83.1 165.1

2 1,059.8 113.5 58.8 182.5

3 36.5 9.2 0.0 0.0

4 9.2 0.0 0.0 0.0

5 0.0 0.0 0.0 0.0

6 0.0 0.0 0.0 0.0

 Total 2,113.5 280.0 141.9 347.6

Thousand acres

Loblolly-shortleaf OakTimberland Natural pine

Table 6—Area of timberland by hardwood damage

zone and forest type, February 1994 ice storm,

northern Mississippi

Damage Oak- Oakzone pine hickory

1 1,197.0 217.3 579.9 102.6 24.4

2 889.0 130.2 432.1 186.7 0.0

3 27.5 0.0 18.3 0.0 0.0

4 0.0 0.0 0.0 0.0 0.0

5 0.0 0.0 0.0 0.0 0.0

6 0.0 0.0 0.0 0.0 0.0

 Total 2,113.5 347.5 1,030.3 289.3 24.4

Thousand acres

Oak-gum- Elm-ashTimberland cypress cottonwood
10

Net volume of live trees in the FIA survey database refers

to the cubic-foot volume of trees with a minimum

diameter at breast height of 5.0 inches and a minimum top

diameter of 4.0 inches diameter outside bark.

Volume loss due to stem breakage and mortality of the

hardwood component was 16.5 percent of the prestorm

net live-tree volume (table 8). Similarly, softwoods lost

15.4 percent of volume. However, the total hardwood

volume loss (208 million cubic feet) was nearly twice that

of softwoods (111 million cubic feet). Timberland basalarea breakdowns may be misleading when making

damage-loss comparisons. Before the ice storm, approximately 40 percent of the live-tree volume was in softwoods, whereas only 30 percent of the basal area was in

softwoods.

Discussion

Slightly more than 1 percent of the timberland area

sustained heavy mortality of trees. The heaviest concentration of probable mortality (about 46,000 acres) showed

volume loss at about 4 million cubic feet of timber. This

pales in comparison to the widespread damage across the

lightly affected areas (zones 1 and 2). Although only 16

percent of the volume in zones 1 and 2 was lost, the

storm’s widespread effect was 77 times the volume loss

within the small timberland area of zones 3 and 4.

Within moderate damage areas (zones 3 and 4), roughly

40 percent of the volume was affected. Overall, 16

percent of the live-tree volume damage was stem breakage and downed trees. Softwoods other than pine and

cypress, which constituted less than 3 percent of the total

volume, were grouped within and treated as pine for

damage assessment.

Over 99 percent of the area showed some form of damage

to canopy or bole. Twelve percent of the records were

interpreted as showing no damage to the volume component, while less than 2 percent showed no damage to the

canopy. Only five records from the video imagery showed

no damage to bole or canopy. These sample location

records represent the extreme edge of the study area or

the premerchantable hardwood component where no

damage was evident. Only 18 records showed pine and

hardwood components to be in a premerchantable stage;

and 12 records predominantly showed pine. All of the

latter showed considerable damage to the pine canopy but

light or no damage to the stems, while the hardwood

damage was moderate or nonexistent.

Timberland area and prestorm hardwood volume were

slightly higher in hardwood zone 1 than in zone 2. At 25

percent, the midpoint damage value in zone 2 was triple

what it was in zone 1 (8.33 percent), as was the hardwood

volume damage. For softwoods, zones 1 and 2 were equal

in timberland area and zone 1 contained more prestorm

softwood volume. Calculations show that zone 2 had

twice the damage of zone 1.

Canopy damage is not very serious when ice causes only

temporary damage, e.g., defoliation and the pruning of

some limbs. However, some of the more serious crown

damage affects tree form by breaking tops and stripping

some large forks and limbs from the bole. This also leads

to immeasurable volume damage in merchantable tops. In

addition to its effect on timber volume, the storm’s more

serious damage to tree form will affect future volume

grade due to growth loss, potential pathogens, and insects.

Species composition and terrain play minor roles in timber

damage. A small amount of hardwood volume damage

results from ice-laden pines falling against hardwoods,

which may break the main bole or, in saturated soils,

uproot them. Other hardwood volume damage occurs in

bottomland soils, which become saturated as rain precedes

the Arctic cold front and its freezing wind.

Where there are gaps in the canopy, hardwood and

softwood stems appear susceptible to windthrow and

breakage in very wet areas and along streams and ditches.

Trees adjacent to open areas are especially susceptible

because there is no surrounding canopy to protect crowns.

As a result, we documented the edge-effect variable during

our earliest interpretation process. An edge is where

timberland meets open lands, e.g., pasture and agricultural

land, rights-of-way for roads and transmission lines, and

water bodies.

Although edge seemed problematic in our design of a

damage equation, less than 50 percent of the video sample

locations contained any type of edge. Less than 15 percent

Table 8—Net volume of live trees by species group and 

damage zone before and after the February 1994 ice storm,

northern Mississippi

Damage Percent

zone damage

1 8.33 656.5 601.8 420.3 385.3

2 25.00 595.0 446.2 304.9 228.7

3 41.67 9.7 5.7 0.2 0.1

4 58.33 a a 0.0 0.0

5 75.00 0.0 0.0 0.0 0.0

6 91.67 0.0 0.0 0.0 0.0

 Total 1,261.2 1,053.7 725.4 614.1

Net volume loss 207.5 111.3

a

Indeterminable.

Million cubic feet

Poststorm

Hardwoods Softwoods

Prestorm Prestorm Poststorm
11

Faulkner, Joanne L.; Miller, Patrick E.; Hartsell, Andrew

J.; London, Jack D. 1993. Forest statistics for north

Mississippi counties—1994. Resour. Bull. SO-180. New Orleans:

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

Experiment Station. 41 p.

Halverson, Howard G.; Guldin, James M. 1995. Effects of a

severe ice storm on mature loblolly pine stands in north

Mississippi. In: Edwards, M. Boyd, comp. Proceedings of the

eighth biennial southern silvicultural research conference; 1994

November 1–3; Auburn, AL. Gen. Tech. Rep. SRS-1. Asheville,

NC: U.S. Department of Agriculture, Forest Service, Southern

Research Station: 147–153.

Hartsell, Andrew J.; London, Jack D. 1995. Forest statistics

for Mississippi counties—1994. Resour. Bull. SO-190. New

Orleans: U.S. Department of Agriculture, Forest Service,

Southern Forest Experiment Station. 89 p.

Jacobs, Dennis M.; Eggen-McIntosh, Susan. 1993. Airborne

videography and GPS for assessment of forest damage in

southern Louisiana from Hurricane Andrew. In: Proceedings of

the IUFRO conference on inventory and management

techniques in the context of catastrophic events; 1993 June

21–24; University Park, PA. [Not paged]. [Available on the web at:

http://www.srs.fs.fed.us/pubs/ja/ja_jacobs001.pdf].

Jacobs, Dennis M.; Evans, David L. 1996. Applications of

airborne videography in forest inventory and analysis and in

assessing catastrophic events. In: Paivinen, Risto [and others],

eds. EFI proceedings: new thrusts in forest inventory: Proceedings of the subject group S4.02-00 ‘forest resource inventory

and monitoring’ and subject group S4.12-00 ‘remote sensing

technology’; IUFRO XX World Congress; 1995 August 6–12;

Tampere, Finland. Joensuu, Finland: European Forest Institute,

International Union of Forestry Research Organizations:

91–104. Vol. I.

NOAA. 1994. Storm data and unusual weather phenomena with

late reports and corrections. Asheville, NC: U.S. Department of

Commerce, National Oceanic and Atmospheric Administration;

National Environmental Satellite, Data, and Information

Service; National Climatic Data Center. 76 p.

Sheffield, Raymond M.; Thompson, Michael T. 1992.

Hurricane Hugo: effects on South Carolina’s forest resource. Res.

Pap. SE-284. Asheville, NC: U.S. Department of Agriculture,

Forest Service, Southeastern Forest Experiment Station. 51 p.

Tansey, John B.; Hutchins, Cecil C., Jr. 1988. South

Carolina’s forests. Resour. Bull. SE-103. Asheville, NC: U.S.

Department of Agriculture, Forest Service, Southeastern Forest

Experiment Station. 96 p.

Van Hooser, Dwane D.; Hedlund, Arnold. 1969. Timber

damaged by Hurricane Camille in Mississippi. Res. Note SO-96.

New Orleans: U.S. Departmentof Agriculture, Forest Service,

Southern Forest Experiment Station. 5 p.

Vissage, John S.; Miller, Patrick E.; Hartsell, Andrew J.

1992. Forest statistics for Louisiana Parishes—1991. Resour.

Bull. SO-168. New Orleans: U.S. Department of Agriculture,

Forest Service, Southern Forest Experiment Station. 65 p.

of the samples showed ice damage resulting from any type

of edge effect. Of the records that showed such damage,

edge appeared not to be the major factor contributing to

bole loss and mortality.

The concept of edge effect also seemed inappropriate

when we determined the prevalence of the domino effect.

Some stands, especially those of evergreen softwoods like

pine and redcedar, displayed appearances of wind shear, as

well as the appearance of trees fallen like dominoes.

Adjacent timber of the same forest type and stand-size

class appeared unaffected by bole mortality and exhibited

only ice-laden canopy damage.

Conclusion

Following a severe ice storm in 1994, GPS and airborne

videography techniques provided a GIS-mapped assessment of damage to forest resources in northern Mississippi. The GIS map links video interpretation schemes

with data from the recently completed FIA field survey to

provide estimates of timber volume losses. During times of

limited fiscal resources, this technique can reduce the need

for extensive ground analysis of damaged areas.

Natural catastrophic damage can be characterized spatially

through interpretation of airborne videography transects.

Global Positioning System coordinates encoded onto

video images facilitated development of GIS products for

the impacted area. Together with existing data bases of

forest resources, GIS products enabled analysts to develop

estimates of timber damage soon after the storm event.

A relatively small portion of the study area received

concentrated heavy damage to the forest resources, i.e.,

only 3 percent of basal area before the ice storm. Yet the

much broader area that sustained light damage actually

contained 99 percent of the damage resulting from

mortality and volume loss.

We need to develop techniques for determining volume

loss from merchantable top breakage; and we should find a

means, likewise, of estimating current and future loss to

damaged premerchantable timber.

Literature Cited

Daniels, Robert. 1995. 1994 harvest of forest products. Forest

resources: market notes, technical notes, research notes,

newsletters. Starkville, MS: Mississippi State University,

Mississippi Cooperative Extension Service. 10 p.

Daniels, Robert. 1996. 1995 harvest of forest products. Forest

resources: market notes, technical notes, research notes,

newsletters. Starkville, MS: Mississippi State University,

Mississippi Cooperative Extension Service. 10 p.
12

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 U.S. Department of Agriculture (USDA) prohibits discrimination in all

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is an equal opportunity provider and employer.

During February 8–11, 1994, a severe winter storm moved from Texas and Oklahoma to the midAtlantic depositing in northern Mississippi a major ice accumulation of 3 to 6 inches. An assessment of

forest resource damage was initiated immediately after the storm by performing an airborne video

mission to acquire aerial imagery linked to global positioning coordinates. Interpretation of the aerial

video imagery generated data that were used to map zones of similar damage severity. The Geographic

Information System map data were linked with recent State forest resource inventory data to provide

estimates of forest resource damage. There were 2.1 million acres of forest land within the 3.7-millionacre study area in northeast Mississippi. Less than 1 percent of the forest land remained untouched by

some degree of damage. Net loss to live-tree volume, due to probable mortality, amounted to 16.5

percent of hardwoods and 15.3 percent of softwoods. The majority of volume loss occurred in areas that

received about 25 percent mortality to the forest resource.

Keywords: Aerial reconnaissance, airborne video system, GIS, GPS, ice storm damage, isozone,

Mississippi.

Jacobs, Dennis M. 2000. February 1994 ice storm: forest resource damage assessment in northern

Mississippi. Resour. Bull. SRS-54. Asheville, NC: U.S. Department of Agriculture, Forest Service,

Southern Research Station. 11 p.
13

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