
“Beware the oak, it draws the stroke. 
Avoid the ash, it courts the flash. 
Creep under the thorn, ’twill save from 
harm.” 
—Proverb. 

A pine tree killed by lightning 
horizon. Presently the low rum- 
bling of thunder could be heard. 
The black blanket came on apace. A 
dazzling flash parted the heavens, there 
was the sustained crackling of light- 
ning, then a deafening crash. The 
lightning had struck. Another of 
Nature’s sentinels had been rent apart. 
This time it was an aspen, despite 
local belief of the immunity of the 
aspen from lightning. It might have 
been a beech, or a locust, which in some 
sections of the country are still re- 
garded as peculiarly free from attack 
by lightning. On the other hand, cer- 
tain trees in some sections are regarded 
as outstanding lightning hazards. In 
Boston, for example, the memorial elm 
under which General Washington re- 
ceived his command of the American 
Army and which has been struck sev- 
eral times by lightning is pointed out 
as an example of the susceptibility of 
the elm to lightning. 
Everywhere throughout the world 
1 tes clouds were gathering on the 
When Lightning Strikes 
Electrical Storms in Relation to Forestry 
By C. MORAN 
there continues to persist the age-old 
fallacy that certain species of trees 
attract, or are immune from, lightning 
more than others. The elder Pliny said 
that “lightning never strikes’ the 
laurel.” Wreaths of laurel leaves were 
worn by ancient rulers to protect them 
from the lightning of the gods. Later, 
trees such as the walnut, birch, elder, 
and live-for-ever were planted near 
houses because of the belief in their 
immunity from lightning. These be- 
liefs have given rise to many interest- 
ing theories regarding the relation of 
lightning to trees. 
TATISTICS show that, under favor- 
able circumstances, any kind of 
tree may be struck by lightning. Trees 
are the objects most often struck be- 
cause they are the most numerous of 
all objects. Their spreading branches 
in the air and spreading roots in the 
ground present the ideal form for con- 
ducting an electrical discharge to the 
earth. Yet less than 25 per cent. of the 
people killed by lightning are those 
who have sought refuge under trees. 
Certain trees in some sections are not 
struck because the number of that 
species is in the minority. The great- 
est number of trees struck in any local- 
ity are the dominant species. 
An investigation by the United States 
Forest Service shows that lightning is 
second in the list of leading causes of 
forest fires. Although only 2 per cent. 
of the trees struck by lightning on the 
National Forests are ignited, more than 
17 per cent. of the number of fires are 
due to this cause. The survey shows 
that more trees are struck by lightning 
on the Colorado Plateau in the terri- 
tory extending from western New 
Mexico to Southern Utah, crossing the 
Grand Canyon, and including the White 
Mountains, Black Mesa, and San Fran- 
cisco and Sevier Mountains than in any 
other region of the United States. 
Sixty per cent. of the trees struck in 
this region are Western Yellow Pines. 
In some sections of the region, such 
as on the volcanic cinder flats east of 
San Francisco Mountain, fully one- 
half the mature trees have been killed 
or injured by lightning. In one case 
i00 trees in a small area were noted as 
having been struck within a four-year 
period. Twenty trees were struck dur- 
ing one afternoon on a 20-acre plot. 
According to the local Forest Ranger, 
“nearly every tree for jlong distances 
along the Guam and Redrock telephone 
lines has been struck, starting where 
the wire is fastened to the trees. The 
lightning jumps the wire and runs 
down the trees.” 
Destruction of trees by lightning is 
naturally more severe in forests on 
mountain slopes and summits that are 
particularly exposed, and which lie in 
so-called “lightning zones.” <A _ light- 
ning zone is conceived to be a layer of 
the lower atmosphere—a thundercloud 
stratum—which touches the summits of 
some mountains and the lower slopes 
of others. The altitude of the zone 
varies, as it is subject to modulations 
in the same way as are other atmos- 
pheric strata flowing over or around 
high points. 
N Minnesota, Wisconsin and Michi- 
gan 70 forest fires a year are caused 
by lhghtning striking such trees as the 
Norway pine, white pine, and tama- 

Trees destroyed by a lightning fire in Plumas National Forest 
Page 532 
