THE CONCEPT OF FOREST HEALTH

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THE CONCEPT OF FOREST HEALTH Reading
Text - Chapter 1 Also read Chapter
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A healthy old-growth forest ecosystem in Mt.
Rainier National Park
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A healthy young Douglas-fir forest?
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Unhealthy forests in eastern Oregon and British
Columbia - high mortality due to bark beetles
and root diseases
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High incidence of dwarf mistletoe in eastern
Washington due to fire suppression and high
grading over the last 100 years. Unhealthy?
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A monoculture of Norway spruce in Germany.
Healthy?
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A thinned Scots pine forest in Finland. Healthy?
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Exotic Monterey pine plantation in Australia.
Note lack of understory. Is this a healthy
forest?
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Dead trees at Clingmans dome, Great Smoky
Mountains National Park (left)and Mt. Mitchell,
NC (below). Initially attributed to acid rain,
but mostly due to the Balsam woolly adelgid
Definitely unhealthy
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TOPICS COVERED 1. Disturbance in forest
ecosystem 2. Definitions of forest health 3.
Characteristics of healthy forests 4.
Indicators of forest health problems 5. Causes
of forest health problems 6. Forest health
conditions in the U.S. 7. Influence of human
activities - forest management, air pollution,
introduced pathogens and insects 8. Forest
health monitoring networks
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1. DISTURBANCE IN FOREST ECOSYSTEMS
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Forest are continually being disturbed Disturbanc
e agents Biotic diseases Insects Abiotic agents
fire, adverse weather - wind, drought,
flooding, temperature extremes (Abiotic
disease) Human activities anthropogenic air
pollution (Abiotic disease) forest
management - e.g., fire suppression,
clearcutting, fertilization, thinning
global warming All these factors interact -
especially insects, diseases and fire
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Range from utilitarian (timber) to ecosystem
perspective. Ecosystem management is now
widely practiced Ecosystem Management implies
that land is not managed for a single tree
species and involves (1) Ecosystem complexity -
biodiversity (2) Biological legacies (green
trees, logs, snags) (3) Landscape perspective
(i.e, large space and time scales) Forests
managed this way should be healthier
2. DEFINITIONS OF FOREST OR ECOSYSTEM HEALTH
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Definitions of a healthy forest - a condition
where biotic and abiotic influences on forests do
not threaten management objectives now and in the
future - A fully functioning community of plants
and animals and their environment - an ecosystem
in balance - a condition of forest ecosystems
that sustains their complexity while providing
for human needs - the ability of forest
ecosystems to bounce back after being stressed -
the ability of a forest to recover from natural
and human stressors
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- a healthy ecosystem should be free from
distress syndrome, where the syndrome is
characterized by reduced primary productivity,
loss of nutrient capital, loss of biodiversity,
increased fluctuations in key populations,
retrogressions in biotic structure, and
widespread incidence and severity of diseases,
insects and fires.
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3. CHARACTERISTICS OF HEALTHY FORESTS Need to
take into account a. That healthy forests
involve more than health of individual trees
(dead trees occur naturally in ecosystems) b.
Natural large-scale disturbances (fire, wind,
insects) c. Linkages between aquatic and
terrestrial ecosystems (salmon
issues) Measurements of ecologically healthy
watersheds include water yield and quality,
community composition, forest structure, health
of the riparian zone, fish production,
wildlife use, and genetic diversity.
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4. INDICATORS OF FOREST HEALTH PROBLEMS 1.
Trees and understory plants should be vigorous
and healthy species, age class distributions,
stand densities should be within historical
ranges, and growth and mortality should be
consistent with ecosystem type and age of
dominant trees 2. Vegetation diversity should be
balanced between the supply and demand for
light, nutrients, water and growing space 3.
Forest should be capable of tolerating and
recovering from known disturbance (e.g., fire and
wind) 4. Soil erosion should be at a minimum
clean water should flow in streams except during
extraordinary runoff events, and stream banks
need to be stable and riparian vegetation ample
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5. Aquatic species should be diverse and aquatic
indicator species should be present in expected
numbers 6. Wildlife diversity and presence need
to be appropriate for the ecosystem, especially
in riparian zones 7. Insect, disease, and fire
frequencies need to within the normal ranges for
the ecosystem
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5. CAUSES OF FOREST HEALTH PROBLEMS
Major forest health issues Species loss, insect
and disease epidemics, excessive wildfires, water
quality and quantity problems, impacted wildlife,
nutrient imbalances, soil and watershed
damage Caused by 1. large area disturbances
due to logging and grazing and conversion to
uniform,even-aged, overly dense forest - usually
makes native diseases and insects worse 2. Exotic
introductions (gypsy moth, white pine blister
rust, plants- kudzu, Scots broom 3. Change in
the environment - air pollution, global change 4.
Excessive fuel loading in forests - largely due
to fire suppression
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6. FOREST HEALTH CONDITIONS IN THE U.S.
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List of Current Major Forest Health Problems in
the U.S. 1. Fire - particularly in inland
Northwest and Southwest 2 Insects -
defoliators - Gypsy moth, Asian Gypsy Moth,
Spruce budworm, Douglas-fir tussock moth -
bark beetles - Mountain pine beetle, - wood
borers - Asian longhorned beetle - sucking
insects on foliage, branches and stems -
hemlock adelgid (eastern U.S.), balsam woolly
adelgid introduced insects
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Crown fire in interior west forests
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Defoliation by the Douglas-fir tussock moth in
the interior west
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Gypsy moth defoliation in the eastern U.S.
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Damage by the Asian long horned beetle
in hardwood species
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3. Diseases Root diseases - Armillaria root
disease, Annosus root and butt rot,
Phytophthora root disease Canker diseases -
chestnut blight, sudden oak death,
madrone canker, pitch canker Foliage
diseases - Swiss needle cast, Dothistroma needle
blight Twig and foliage diseases -
dogwood anthracnose, sycamore anthracnose
Vascular wilts - Dutch elm disease, oak wilt
Rusts - White pine blister rust, southern
fusiform rust, poplar rust 4. Air pollution -
acid rain and ozone Introduced diseases
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Mortality in white bark pine caused by the
introduced white pine blister rust.
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Chestnut blight
Dutch elm disease
BOTH ARE INTRODUCED DISEASES CAUSING LARGE-SCALE
MORTALITY
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SWISS NEEDLE CAST - NATIVE DISEASE
Defoliation from Swiss needle cast on Douglas-fir
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SUDDEN OAK DEATH An introduced
caused by Phytophthora ramorum
The current host list includes California black
oak, coast live oak, Shreve oak, tanoak,
rhododendron, California bay laurel, big leaf
maple, madrone, manzanita, huckleberry,
California honeysuckle, toyon, California
buckeye, California coffeeberry, Douglas-fir and
coast redwood and Arrow wood (in Germany, the
United Kingdom, and the Netherlands).
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7. INFLUENCE OF HUMAN ACTIVITIES - FOREST
MANAGEMENT, AIR POLLUTION, INTRODUCED PATHOGENS
AND INSECTS Case Studies 1. The inland western
U.S. 2. Influence of introduced pathogens and
insects 3. Air pollution
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Dry Interior west Fire suppression high tree
density drought stress root diseases bark
beetles defoliators
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Solution - Attempt to reintroduce frequent low
intensity fire and thinning into forest
management in the interior west
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Natural recovery of lodgepole pine forests 5
years after the Yellowstone wildfire. Note
carpet of young seedlings.
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A German Norway spruce forest monitored for
forest health. Unhealthy trees have flat tops
largely attributed to air pollution and acid
rain. Air pollution influences forests worldwide.
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8. FOREST HEALTH MONITORING NETWORKS
1. The U.S. National Forest Health Monitoring
Network 2. Forest Health Monitoring in western
Europe 3. The Canadian system
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The USDA Forest Service, Forest Health
Monitoring (FHM) is a national program designed
to determine the status, changes, and trends in
indicators of forest condition on an annual
basis. The FHM program uses data from ground
plots and surveys, aerial surveys, and other
biotic and abiotic data sources and develops
analytical approaches to address forest health
issues that affect the sustainability of forest
ecosystems. REGIONS North Central Region
Northeastern Region Southern Region
West Coast Region Rocky Mountain Region
Forest Health web site http//www.fs.fed.us/forest
health