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, “old-growth forests” can develop.

Many specialized animal species, like the northern spotted owl, are found in old-growth 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 ImpactsLogging

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.

What do you think the criteria should be for determining how

much old-growth forest is preserved in western North

America?

An exam question: