Download Temperate Forests

Temperate Forests
Temperate forests are found primarily in
North America and Eurasia.
Successional Dynamics
In temperate forests, ecological
succession is a critically important
factor in determining biodiversity.
What is biotic
succession?
Ecosystems undergo fundamental changes during
the successional process. Early in succession,
nutrients may decline in the soil. Colonization by
plants may move slowly. When coverage is more or
less complete, biomass may accumulate more
rapidly. During this period, nutrients also accumulate
rapidly. Late in the successional process, nutrients
may be tied up in dead plant material and less
available to the ecosystem.
Species composition of plants and
animals may change dramatically during
succession. Generally, the greatest
diversity is found during the middle
stages.
Under some
conditions,
particularly when
major disturbances
are rare, “oldgrowth forests” can
develop.
Many specialized
animal species, like
the northern spotted
owl, are found in oldgrowth forests. This
makes them a
particularly critical
habitat, and the
subject of many
debates regarding
conservation.
Spotted owls have a home range of
800 to 2000 hectares in old-growth
forests. Old-growth timber is valued
at over $10,000 per hectare.
So, preserving habitat for 500 pairs
of owls involves how much timber?
About $4 billion dollars worth
If successional changes bring large
changes in the dominant species, there
are often species that are adapted to
different stages of the successional
process.
Organisms that are adapted to particular
successional stages often have distinctive
characteristics.
Early Successional Species
Mule deer – Odocoileus hemionus
Late Successional
Species
Woodland caribou
Rangifer tarandus
Early Successional Species
Ruffed grouse – Bonasa umbellus
Late Successional Species
Spruce grouse – Canachites canadensis
Early Successional Species
Mourning dove – Zenaida macroura
Late Successional Species
Passenger pigeon – Ectopistes migratorius
Human Impacts
Logging
Conversion to other use
Fragmentation
Invading species
Overprotection of ungulates
Air pollution
Virtually no
virgin deciduous
forests remain,
and most
coniferous
forests have
been cut one or
more times.
Managing Succession
Must consider:
1. Amount of habitat in different stages.
2. Size and location of areas in these stages.
3. Nature and intensity of human use.
Many species require habitat in late
successional stages.
Red-cockaded woodpecker requires large
pine trees, infected by a type of fungal
disease called “red heart” disease. This
disease enables the woodpecker to
excavate nest chambers. Requires special
management practices.
Managing Fire Relationships
In many areas, protecting forests
from fires has led to dramatic
changes in the nature of the
forest.
In many areas, the
policy is now to
allow natural fires to
burn. (Let Burn
Policy)
Klamath National Forest - Fire and
Aviation, Wildland Fire Use
This policy backfired in
Yellowstone National Park in 1988.
Forest fires
burned about
36% of the
Park and
surrounding
areas. $125
million was
spent trying
to stop the
fires.
Global climate
changes may
have dramatic
effects on
distribution of
temperate
forests.
An exam question:
What do you think the criteria
should be for determining how
much old-growth forest is
preserved in western North
America?