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MAINE DEPARTMENT OF CONSERVATION
Maine Forest Service
Many spruce stands on the islands and headlands
of coastal Maine are overmature and growing on poor sites.
Most stands have not been managed to promote more vigorous tree
growth. These factors combined with damage caused by
several active spruce pests and the added stress of recent
adverse weather conditions have significantly affected the health
of coastal spruce.
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| Coastal spruce, symptomatic of declining stand health |
The History of Coastal Spruce Stands
Red and white spruce constitute the predominant forest type on
much of the central and eastern Maine coastline and
offshore islands. During the 1800s many of these islands
and headlands were cleared of the original spruce stands and used
for agricultural, commercial, and residential purposes. In
the early 1900s, island communities began to decline and many
cleared areas reverted to forest. Some of the larger
islands were logged extensively between 1930 and 1950, but little
large scale harvesting has occurred since. Stands of large,
overmature white and some red spruce persist in many previously
cleared areas. White spruce out-competed the original red spruce
on many sites. Regenerating coastal spruce trees,
especially white spruce, grew very rapidly for 30 to 50 years in
the moist and moderate maritime environment. However, most
stands are now much older than 50 years. Without management
to promote stand vigor, growth has stagnated. Many
stands contain trees 60 to 120 years old, that exceed 15" in
diameter, are 80 feet in height, and have grown very slowly for
at least 20 years. Unfortunately, island and coastal sites
have shallow rocky soils that limit tree growth and
longevity. Because coastal spruce stands have exceeded the
growth capacity of these sites they are now in decline.
Symptoms
Declining trees often have a sharply reduced foliage compliment
with foliage clumped at the ends of branches and very little
foliage near the bole. Foliage may have a yellowish or
reddish cast. Tops of some trees appear bare and may have
numerous dead or dying branches. Tree boles often show
outward evidence of rot or disease and holes in the bark from
woodborers, bark beetles, and woodpecker activity are
common. Low vigor stands usually contain some large
standing and fallen dead trees.
Causes of Declining Spruce Health
In addition to generally poor vigor, many coastal stands
increasingly fall victim to pest organisms and climatic
stress. Severe wind storms caused significant blowdown in
coastal stands during 1991 and 1996. The majority of mature
spruce stands on the Maine coast now contain some wind damaged
areas that have created openings in the canopy and will increase
the impact of future wind storms. Severe droughts in 1994
and 1995 caused added stress to spruce trees on shallow,
ledgy sites. Pests affecting spruce vigor and survival
include a recent outbreak of hemlock looper (a defoliator of fir
and spruce), a high occurrence of dwarf mistletoe (a parasitic
plant that weakens host trees), and an active infestation of
spruce beetle (a native bark beetle that can kill healthy
spruce). From 1990 to 1992 hemlock looper killed spruce
trees in some stands and significantly stressed other spruces in
coastal areas. Dwarf mistletoe is currently killing some
spruce trees and weakening others. A spruce beetle outbreak
that intensified in 1992 remains active and is killing a high
percentage of the large spruce in several areas.
Coastal Spruce Management
Most of the agents killing or causing stress to mature coastal
spruce have been exacerbated by the lack of stand
management. Most agents affecting these stands have no
effective control strategies. Trees are large, overmature,
tightly spaced, and are on generally poor sites that can not
support much additional stand growth. If nothing is done in
these stands their age and maturity will result in a steady
deterioration and eventual widespread tree mortality. Other
stands will experience catastrophic mortality from events such as
severe spruce beetle attack. For landowners who find these
alternatives unacceptable, the only reasonable alternative is to
restore and maintain long term stand vigor through ongoing stand
management. Removal of large, old trees will be essential
in many stands to promote new growth, but most areas already
contain younger more vigorous trees and regeneration that should
lessen visual impacts. Landowners interested in management
of their coastal spruce stands should seek the advice of a
licensed professional forester. (April 1997)
For further information contact:
Insect & Disease Management Laboratory
Maine Forest Service
50 Hospital St.
Augusta, Maine 04330
Telephone: (207) 287-2431
Maine Forest Service
22 State House Station
Augusta, Maine 04333-0022
Telephone: (207) 287-2791 or within Maine only 1 (800) 367-0223
TTY: (207) 287-2213
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