134 CHAPTER 6 Ecosystems and Evolution
Average monthly precipitation in cm141618202212
10
8
6
4
2
0
Months1015205
0
–5
–10Average monthly temperature in°CJFMAMJJASOND
Based on data from http://www.worldclimate.comSarah Leen/NG Image Collectionwestern hemlock, Douglas fir, western red
cedar, Sitka spruce, and western arborvitae
(Figure 6.6). Temperate rain forests are rich
in epiphytes, smaller plants that grow on the
trunks and branches of large trees. Epiphytes
in this biome are mainly mosses, club mosses, lichens,
and ferns, all of which also carpet the ground. Squirrels,
wood rats, mule deer, elk, numerous bird species, and
several species of amphibians and reptiles are common
temperate rainforest animals.
The temperate rain forest is a rich wood producer,
supplying lumber and pulpwood. Overharvesting the
original old-growth (never logged) forest can devastate
that biome, because such an ecosystem takes hundreds of
years to develop. Once harvested, the old-growth forest
ecosystem never has a chance to fully recover. Issues sur-
rounding logging of old-growth temperate rain forests
of the Pacific Northwest are discussed in the Chapter 13
case study, “The Tongass Debate over Clear-Cutting.”Temperate Rain Forest
A coniferous temperate rain forest occurs
on the northwest coast of North America.
Similar vegetation exists in southeastern
Australia and in southern South America.
Annual precipitation in this biome is high—more than
127 cm (50 in)—and is augmented by condensation of
water from dense coastal fogs. The proximity of temperate
rain forest to the coastline moderates its temperature so
that the seasonal fluctuation is narrow; winters are mild,
and summers are cool. Temperate rain forest has rela-
tively nutrient-poor soil, though its organic content may
be high. Cool temperatures slow the activity of bacterial
and fungal decomposers. Thus, needles and large fallen
branches and trunks accumulate on the ground as litter
that takes many years to decay and release nutrient miner-
als to the soil.
The dominant vegetation in the North American
temperate rain forest is large evergreen trees such as
This temperate biome has large amounts of precipitation.
Photographed in the Hoh Rain Forest in Washington State.
Climate graph shows monthly temperatures and precipitation
for Estacada, Oregon.
temperate rain
forest A coniferous
biome with cool
weather, dense fog,
and high precipitation.Interpreting Data
What is the range of average monthly temperatures in
this temperate rain forest? How does this compare to the
range of average monthly temperatures in the temperate
deciduous forest (facing page)?/i«iÀ>ÌiÊÀ>ÊvÀiÃÌÊUÊ}ÕÀiÊÈ°ÈÊ