United States Department of Agriculture

Forest 

Service

Research Paper 

NRS-25

Northern 

Research Station February 2014

Tree Survival 15 Years after the 

Ice Storm of January 1998

Walter C. Shortle

Kevin T. Smith

Kenneth R. Dudzik
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Abstract

The regional ice storm of early January 1998 was a widespread disturbance for millions of 

acres of forest in northeastern New York, northern New England, and southern Quebec. 

Tree crowns were partially or totally lost as stems snapped and branches broke with the 

weight of the deposited ice. We tracked the effect of crown injury on a large sample of 

northern hardwood trees within the storm footprint. Comparisons of tree survivorship from 

5 to 15 years after the storm showed that paper birch was most sensitive to storm impact 

followed by yellow birch. Root-rot disease present prior to the storm was associated with 

the high mortality of birch. Although dramatic, mortality associated with the storm during 

this period was consistent with mortality expected from normal stand development of 

northern hardwoods as illustrated by the hardwood stocking chart.

The Authors

WALTER C. SHORTLE is a research plant pathologist, KEVIN T. SMITH is a plant 

physiologist, and KENNETH R. DUDZIK is a forester with the U.S. Forest Service, 

Northern Research Station, Durham, NH.

Cover Photos

Kevin T. Smith (left, 1998) and Walter C. Shortle (right, 2003) assess tree crown injury and 

recovery after the 1998 ice storm in the northeastern United States and adjacent Canada. 

Photos by Kenneth R. Dudzik, U.S. Forest Service.

Manuscript received for publication 1 October 2013
1

INTRODUCTION

Ice storms and associated tree injury are part of the 

natural ecology of northeastern forests, occurring in 

some portion of the landscape every year. An unusually 

extensive and severe 3-day storm in early January 

1998 exposed nearly 25 million acres of forest from 

northwestern New York and southern Quebec to the 

south-central Maine coast to extreme icing (Fig. 1). Th is 

storm was unusual for both its geographic extent and for 

the duration of icing. Trees throughout the region were 

injured as branches and stems broke and forks split under 

the weight of the ice. Th ese injuries reduced the size of 

tree crowns and exposed wood to infection by wooddestroying fungi.

In anticipation of concern for the long-term eff ect of 

the storm on the forest resource, we partnered with 

various state, commercial, and federal land managers to 

establish a “tag and track” study to determine the eff ect 

of the storm on tree survival, growth, and wood quality. 

Study details and research fi ndings after 4 years have 

been published (Shortle et al. 2003). Th e following are 

observations primarily at 5 and 15 years after the storm.

METHOD SUMMARY

In October 1998, 584 trees of six northern hardwood 

species with various levels of crown loss were selected 

and tagged from six locations (Fig. 1) within the storm 

footprint from eastern Vermont, across New Hampshire, 

and into western Maine. Large pole-sized trees (8-11 

inches diameter at breast height [d.b.h.]) and small 

sawtimber (12-22 inches d.b.h.) were classifi ed at each 

location on the basis of crown loss: 

• Class A — crown loss less than one-half

• Class B — crown loss of one-half to three-quarters

• Class C — crown loss of more than three-quarters 

of the live crown

To determine the eff ect of crown loss on wound 

response, representative trees were drilled at breast height 

with a 3/8-inch bit to a depth of 2 inches. Increment 

cores also were collected from all trees in 2000 or 2002 to 

determine the eff ect of crown loss on growth.

Th e proportion of survivors for all 584 trees after 5 years 

was determined at the end of the 2002 growing season. 

Between 2002 and 2012, two of the six study locations 

were harvested for fi nancial, rather than biological, 

considerations with the loss of 176 tagged trees from the 

study. In part due to the loss of 57 percent of the sugar 

maple (Acer saccharum) in classes B and C and 84 percent 

of all red maple (Acer rubrum), classes B and C were 

pooled into the combined class B+C for all comparisons.

Th e proportion of survivors after 15 years for all 366 

remaining trees was determined in September 2012. 

Tree survival was summarized by tree size and species for 

crown loss class A and combined crown loss class B and 

C at 5 and 15 years after injury.

OBSERVATIONS

After 5 years for all tree species except paper birch (Betula 

papyrifera), 99 percent of class A trees and 95 percent of 

combined class B+C trees survived (Table 1).

Figure 1.—Ice storm site map. The red stars show the six 

locations where trees were tagged.

Table 1.—Percent survival of northern hardwood trees 

5 and 15 years after crown loss due to the January 1998 

ice storm.

Loss class

 5-year survival 15-year survival

Tree species

A 

(<half)

BC 

(>half)

A 

(<half)

BC 

(>half)

Sugar maple 100 99 100 94

Yellow birch 98 93 93 70

White ash 100 100 100 97

Beech 100 97 90 82

Red maple 100 100 100 100

Paper birch 89 68 57 23

Overall 99 95 95 76
2

Mortality of paper birch within 5 years following the 

storm occurred in both the pole and sawtimber size classes 

(Table 2), with a higher percentage among smaller trees.

Dissection of dead and dying trees indicated that the 

main contributing factor to death of paper birch at 5 

years was advanced stages of armillaria root-rot disease 

(Fig. 2).

Th e few yellow birch (Betula alleghaniensis) trees that died 

among all crown loss classes during the fi rst 5 years also 

had armillaria root disease which was likely established 

prior to the 1998 storm. In the fi rst 5 years, for maple, 

only a single large sugar maple and none of the red maple 

died (Table 2). No white ash (Fraxinus americana) and 

only a single large American beech (Fagus grandifolia) in 

class B died in the fi rst 5 years after the storm.

Fifteen years after the storm, 90 to 100 percent of class 

A trees survived in all species except paper birch (Table 

1). Several paper birch that escaped heavy crown damage 

died, presumably from root disease (Table 3).

All the smaller paper birch in combined class B+C died 

and most, but not all, larger paper birch died. Some of 

the larger birch with major crown loss survived. Th ese 

survivors appeared to have sound root system at the time 

of the storm. Sugar maple, red maple, and white ash in 

classes B and C had survival rates in the same range as 

class A trees, although few red maple remained in the 

sample due to harvesting (Table 3).

Th e sugar maple and beech that died after 15 years were 

larger trees with major crown loss (Table 3). Th e only 

ash to die was a smaller tree that lost virtually all its 

crown. Th e survivorship proportion after 15 years for 

yellow birch and beech was 70 percent and 82 percent, 

respectively (Table 1).

In the absence of the 1998 storm, some tree mortality 

would be expected as a consequence of stand 

development. Th e expected decrease in the number of 

trees per acre as trees increase in size has been empirically 

determined and can be represented by a stocking chart.

Table 2.—Total number of tagged trees (number of dead 

trees in parentheses) 5 years after the 1998 ice storm by 

crown loss class for poles (8-11 inch d.b.h.) and sawtimber 

(12-22 inch d.b.h.).

Loss class

Poles Sawtimber

Tree species A B C A B C

Sugar maple 31 19 20 63 39 27(1)

Yellow birch 21 17(2) 8 28(1) 24(1) 21(2)

White ash 5 3 7 14 17 13

Beech 9 1 0 11 19(1) 18

Red maple 16 9 10 10 10 2

Paper birch 14(1) 2(2) 7(5) 5(1) 11(1) 11(7)

Class totals 96(1) 51(4) 52(5) 131(2) 120(3) 92(10)

Table 3.—Total number of tagged trees (number of dead 

trees in parentheses) 15 years after the 1998 ice storm by 

canopy loss class for poles (8-11 inch d.b.h.) and sawtimber 

(8-12 inch d.b.h.).

Loss class

Poles Sawtimber

Tree species A B C A B C

Sugar maple 21 7 6 49 20(2) 16(1)

Yellow birch 15(2) 9(4) 7 27(1) 17(5) 21(7)

White ash 5 2 7(1) 10 13 10

Beech 9 1 0 11(2) 19(5) 18(2)

Red maple 1 1 1 4 2 0

Paper birch 2(2) 1(1) 7(7) 5(1) 11(6) 11(9)

Class totals 53(4) 21(5) 28(8) 106(4) 82(18) 76(19)

Figure 2.—Extensive armillaria root disease visible beneath 

the bark of the stem fl are on yellow birch. 

Photo by Kenneth R. Dudzik, U.S. Forest Service.
3

Based on the stocking chart (Fig. 3), an increase in mean 

stem diameter of 1 inch is associated with the survival 

of 83 percent and 88 percent of poles and sawtimber, 

respectively.

Th e overall survival rate after 15 years of “tag and track” 

was 84 percent, consistent with the stocking chart. On 

a landscape basis, the mixture of crown injury class A, 

B, and C trees is functioning as expected, although the 

trees that lost more than half their crown to the winter 

storm were dying fi ve times faster than trees that lost 

less than half. Th e regional survey of 22,000 trees after 

the storm indicated that 80 percent of the trees would 

be classifi ed as A with the remaining 20 percent evenly 

distributed as classes B and C.

Nearly equal numbers of the fastest-growing trees 

before the storm (1 to 10 rings per inch of radius [rpi]) 

occurred in classes A and B+C. Fewer intermediate 

(11 to 20 rpi) and slow-growing trees (21 to 40 rpi) 

occurred in class A than in class B+C trees (Fig. 

4a). Survival rates were relatively constant at 89 to 

100 percent for class A trees at all prestorm growth 

rates (Fig. 4b). Faster growing class B+C trees were 

comparable to survivorship of class A trees at 88 percent. 

Survivorship dropped to 68 to 79 percent of trees with 

slower prestorm stem growth rates (Fig. 4b).

After 15 years, the largest category of trees was the 

combined injury class B+C with open holes (Fig. 4c and 

Fig. 5). Class B+C trees were less eff ective in wound 

closure (Fig. 5) than class A trees (Fig. 4d), indicating 

the potential for increased vulnerability from subsequent 

injury from natural or human disturbance. Survival rates 

for all trees with partly or fully closed wounds was 91 to 

100 percent (Fig. 4d).

Figure 3.—Stocking chart for northern hardwood forest stands.

Figure 4.—Distribution of “tag and track” trees for 

prestorm growth (a, b) and post-storm closure (c, d) by 

crown injury class A (white bars) and combined injury 

class B+C (black bars).

Figure 5.—Open (left) and closed (right) bore holes in sugar 

maple. Photos by Kenneth R. Dudzik, U.S. Forest Service.

a 

b d 

100 c 

80 

60 

40 

20 

100 

80 

60 

40 

20 

0 

Number of trees 

Rings per inch 

1-10 11-20 21-40 

Closure 

closed partial open 

Prestorm growth Post-storm closure 

Survivorship (%) 
4

CONCLUSIONS

Across the tracked hardwood species and for the period 5 

to 15 years after the 1998 storm, tree mortality increased 

from 1 to 5 percent for trees that lost less than one-half 

of their crown and from 5 to 24 percent for trees that 

lost more than one-half of their crown. Th e lowest rate of 

survival occurred in birch and was attributed to advanced 

root-rot disease which was more prevalent in paper 

rather than yellow birch. Th e disease was likely present 

in the root system at the time of injury. If the roots were 

sound and the trees were able to replace the crown with 

vigorous sprouting, most injured trees survived through 

the study period.

Storm survivorship varied by tree species, size class, 

prestorm growth rates, and closure of post-storm bore 

holes. Trees with less than one-half crown loss were least 

likely to die in all species studied with the exception 

of paper birch which is a short-lived, early successional 

species. Trees with more than one-half crown loss 

appeared less able to close the bore holes. Trees growing 

more slowly before the storm were more severely 

impacted by crown breakage and loss.

For a local stand, woodlot, sugar bush, park, or backyard, 

tree injury and resulting damage and loss of value could 

be extensive and require rapid treatment or remediation, 

particularly for safety considerations. Th e trees most 

resilient to storm impact are those that are healthy and 

growing well before the storm, whether in a rural or 

urban setting.

However, over the forested landscape and for a decadal 

or greater time scale, this case study suggests that the ice 

storm of 1998 was simply the specifi c agent to maintain 

normal and expectable stocking densities.

ACKNOWLEGDMENTS

We thank Margaret Miller-Weeks and Isabel Munck, 

Forest Health Protection, Northeastern Area, State and 

Private Forestry, for their help in relocating the tagged 

trees.

LITERATURE CITED:

Shortle, Walter C.; Smith, Kevin T.; Dudzik, Kenneth 

R. 2003. Tree survival and growth following ice 

storm injury. Res. Pap. NE-723. Newtown Square, 

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

Northeastern Research Station. 4 p.
Printed on Recycled Paper

Shortle, Walter C.; Smith, Kevin T.; Dudzik, Kenneth R. 2014. Tree survival 15 

years after the ice storm of January 1998. Res. Pap. NRS-25. Newtown 

Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research 

Station. 4 p.

The regional ice storm of early January 1998 was a widespread disturbance for 

millions of acres of forest in northeastern New York, northern New England, and 

southern Quebec. Tree crowns were partially or totally lost as stems snapped and 

branches broke with the weight of the deposited ice. We tracked the effect of crown 

injury on a large sample of northern hardwood trees within the storm footprint. 

Comparisons of tree survivorship from 5 to 15 years after the storm showed that 

paper birch was most sensitive to storm impact followed by yellow birch. Root-rot 

disease present prior to the storm was associated with the high mortality of birch. 

Although dramatic, mortality associated with the storm during this period was 

consistent with mortality expected from normal stand development of northern 

hardwoods as illustrated by the hardwood stocking chart.

KEY WORDS: forest disturbance, armillaria root disease, storm recovery, wound 

closure

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