Savannas and deciduous forests
Temperate deciduous forests Temperate
mixed and Coniferous forests Mediterranean scrub
Taiga Arctic tundra
Areas of ecological difference in the plant and animal species such as
a desert or rain forest can be classified as a specific type of biome. A
biome is a set of terrestrial ecosystems, which are climatically controlled
and have distinctive vegetation. Within this set of ecosystems there is
an exchange of nutrients and biological components such as plants and animals.
These plants and animals have very distinct adaptations to the specific
climate in which they are situated. Although the various biomes of the world
may be widespread on several different continents, the plants which compose
them are very similar due to parallel evolution, which was influenced be
the specific climatic conditions that they were exposed to.
These various biomes can be classified in a number
of ways. In Europe the term biome is not used. The proper term is
plant formations. The major difference between a plant formation
and a biome is that a biome includes the associated animals of the
group of ecosystems. It is this varied idea of how to classify the
plant formations or biomes which leads to several different classification
systems. The nine biomes, which are discussed on this web site,
are those, which will provide an overview of all of the vegetation
of the world.
To understand the differences of the world’s biomes
and what they are composed of a general understanding of how plants
and animals survive on land and the different weather patterns and
geological formations of the earth will be necessary.
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Although oxygen and carbon dioxide are more available,
life for plants and animals on land is not easy. Plants and animals
on land have to deal with the effects of gravity and climatic changes,
along with poor growing conditions and soils. Although plants and
animals have several disadvantage placed on them the number and
diversity of species is amazing. These species are found in a wide
variety of biomes whose distribution is controlled by three factors.
First the distribution of heat from the sun, and the various seasons
of an area, is it always warm with even sun year round like near
the equator or does the amount of sun change and there are distinctive
seasons like in the northern Untied States and Europe. Secondly,
the pattern of global air circulation and which way the winds containing
moisture blow. Third, the various geological features such as mountain
ranges and their orientation.
It is this third factor, geological features of the world
along with location, which creates much of the diversity of the world.
Mountain ranges in the northern hemisphere affect the amount of inland
precipitation, air which is filled with moisture from the ocean flows
east across the mountains where it rises and cools condensing the water
vapor and causing it to rain. This pattern of airflow creates a moist
environment on the western side of the mountains and a dry rain-shadow
effect in the east.
Along with geography location in latitude
and altitude affects plant and animal species. An increase in altitude,
such as climbing a mountain is similar to heading north (in the northern
hemisphere) plant and animal species will be similar at a mountain top
to those which are further north. As one can see there are many factors
which affect plant and animal diversity creating the various biomes of
the world. As one would expect the complex interactions at local levels
will create environments, which are different from any other environment
in the world. For this reason we will discuss each of the various biomes
in general terms to give an overview and better understanding of the diversity
of life on earth. The names and definitions for all of theses biomes has
been presented in a similar fashion in Biology of plants, sixth edition.
Biomes of the World
||Temperature and Precipitation
||High temperature and high rainfall year round.
||Broad-leaved evergreen trees, epiphytes, and lianas.
||The biome with the greatest diversity of species. Infertile soils.
|Savannas and deciduous tropical forests
|High temperature and seasonal drought.
||Grasslands with scattered broad-leaved deciduous or evergreen trees
||Periodic burning is an important aspect.
|Precipitation generally very low except for occasional peaks; maximum
temperature varies with the type of desert.
||Succulents such as cacti; annual herbs.
Adaptations include small leaves, thick cutickles, and photosynthetic
rates with high maximum temperatures.
|Moderately low precipitation; cold winters and warm summers.
||Perennial bunchgrasses and sod-forming grasses.
||Heavily exploited for agriculture.
|Temperate deciduous forests
|Moderate precipitation evenly disributed; cool winters and warm
||Deciduous trees and many perennial herbs.
||The dominant herbaceous plants vary with the seasons.
|Temperate mixed and coniferous forests
|Moderately low precipitation and moderately cold winters.
||Mixtures of deciduous trees and conifers.
||Occur as a transition zone north of the deciduous forest. Also found
in areas with nutrient-poor soils or with less seasonal environments.
|Cool, moist winters and hot, dry summers.
||Evergreen or summer-deciduous, drought-resistant trees and shrubs
in dense thickets.
||Called chaparral in California and maquis around the Mediterranean
|Moderately low precipitation and cold winters, although in the Pacific
Northwest the winters are very wet.
||Forest of evergreen trees.
||Soils are highly acidic and very low in nutrients. Permafrost may
|Very low precipitation in both summer and winter; very cold winters.
||Low shrubs, grasses, sedges, and lichens.
||Permafrost present throughout. Much of the biomass is underground.