Geography Reference
In-Depth Information
5
THE GEOGRAPHY OF ECOSYSTEMS
Biogeography is the term used to describe the geography of the
biological world. It involves the study of the distribution and pat-
terns of life on Earth and of the underlying processes that result in
these patterns. It is biogeography which will be covered by this
chapter. The biosphere is the biological part of the Earth which
incorporates the Earth's surface and a shallow layer below it, the
oceans and the lower atmosphere. Within the biosphere there exist
many ecosystems. Ecosystems are biological communities and the
physical environment that sustains them where energy and nutrient
cycles link the organic and mineral components of the biosphere.
THE BIOSPHERE
The biosphere is characterised by large- and small-scale energy
flows and cycles of nutrients. The Earth's biosphere is not the same
throughout, but has patterns of distinctive regions at all scales from
the global to the tiny. Variations within the biosphere may result
from factors including climate, geology, soil type, human action
and biotic processes.
Ecological variables
Light
Photosynthesis by green plants captures carbon and oxygen from the
atmosphere and water from either the atmosphere or the Earth's
surface and combines these to produce complex carbohydrates,
which are the building blocks of all life. The energy for photosynthesis
