Terrestrial biomes are categorized by their major plant growth forms
Convergent evolution explains why we can recognise an association between the forms of
organisms and the environments in which they live. Because of convergent evolution, can
categorise terrestrial ecosystems by dominant plant forms that are associated with distinct
patterns of seasonal temperatures and precipitation. Aquatic biomes are characterized by
distinct patterns of depth, flow, and salinity. Biomes provide convenient reference points for
comparing ecological processes around the globe, which makes the biome concept a useful
tool that enables ecologists to understand the structure and function of large ecological
systems. Exceptions are that boundaries between biomes can be unclear and not all plant
growth forms correspond to climate in the same way. Plant communities reflect factors
other than temperature and rainfall. Topography, soils, fire, seasonal variations in climate,
and herbivory all affect which species can live in different plant communities.
, terrestrial biomes
Tundra
Boreal forests (also known as taiga)
Temperate rainforest
Temperate seasonal forests
Woodlands/shrublands
Temperate grasslands/cold desert
Tropical rainforest
Tropical seasonal forests/savannahs
Subtropical deserts
Tundra
Tundra soils contain few nutrients. They also tend to be acidic because of their high content
of organic matter, which is the result of cold conditions dramatically slowing the
decomposition of organic matter. In this nutrient-poor environment, plants hold their
foliage for years. The tundra is found in the Arctic regions of Russia, Canada, Scandinavia
and Alaska and in the Antarctic regions.
Boreal forests
Stretching in a broad belt centred at about 50° N in North America and about 60° N in
Europe and Asia lies the boreal forest. Since evaporation is low, soils are moist throughout
most of the growing season. Because of the low temperatures, plant little decomposes very
slowly and accumulates at the soil surface, forming one of the largest reservoirs of organic
carbon on Earth. The needle litter produces high levels of organic acids, so the soils are
acidic, strongly podzolized and generally of low fertility. The vegetation is extremely frost-
tolerant, however, since few species can survive in such harsh conditions, species diversity is
very low. The boreal forests are used for timber products.
temperate rainforests
these conditions are due to nearby warm ocean currents. The mild, rainy winters and foggy
summers create conditions that support evergreen forests. Support few species.
Temperate seasonal forests
Winter temperatures can drop below freezing in this biome. The environmental conditions
in this biome fluctuate much more than they do in the temperate rainforests because they
do not benefit from the moderating effects of nearby warm ocean waters. Soils are often
podzolized, tend to be slightly acidic and moderately leached, and contain abundant organic
matter. Warmer and drier parts of the temperate seasonal forest biome, especially where
soils are sandy and nutrient poor, tend to develop needle-leaves forest dominated by pines.
The rapid decomposition rates and sandy soils lead to the low availability of nutrients. Since
soils in this biome tend to be dry, fires are frequent, although most species are able to
resists fire damage.
Woodlands/shrublands
Because this type of climate is found around much of the Mediterranean Sea, it is often
referred to as a Mediterranean climate regardless of where it is actually found. Although
there is a 12-month growing season, plant growth is limited to dry conditions in the summer
and by cold temperatures in the winter. Has sclerophyllous vegetation.
Temperate grasslands/cold deserts
Plant growth is constrained by a lack of precipitation in the summer and by cold
temperatures in the winter. As the biome name suggests, the dominant plant forms in
temperate grasslands are grasses and nonwoody flowering plants that are well adapted to