podzols (Spodosols). Such soils have a low supply of bases and a horizon in which organic
matter and iron and aluminum have accumulated.
They are strongly leached, but have an upper
layer of humus. Cool temperatures inhibit bacterial activity that would destroy this organic matter in tropical regions. Deficient in calcium,
potassium, and magnesium, soils are generally
acidic. Thus, they are poorly suited to crop production, even though adequate rainfall is generally assured. Conifers thrive here.
Because of the availability of soil water
through a warm-summer growing season, this
environment has an enormous potential for food
production. North America and Europe support
dairy farming on a large scale. A combination of
Fig. 6.3 Climate diagrams
from the various divisions
of the humid temperate
domain: mixed
deciduous–coniferous
forest regions (continental
with cold winters and warm
summers) and deciduous
forest region (more
moderate), broadleaf
evergreen forest region
(very rainy with hot
summers), oceanic
broadleaf forest region
(rainy with warm
summers), prairie region
(cold winter with warm
summer), and
sclerophyllous regions of
California (dry summer).
Redrawn from Walter et al.
(1975)
58
6 The Humid Temperate Ecoregions