They are also valued for their contribution to ecosystem services â ecosystem functions that are of direct benefit to humans through their action on soil processes. Earthworm benefits to ecosystems Earthworms are sometimes known as âecosystem engineersâ because they significantly modify the physical, chemical and biological properties of the soil profile. These modifications can influence the habitat and activities of other organisms within the soil ecosystem.
The Northern Hemisphere includes all of North America, the northern reaches of South America, about two-thirds of Africa, all of Asia excluding (parts of Indonesia) and all of Europe.he planet's four hemispheres are each shaded a dark gray. The Equator, that imaginary horizontal line at 0Âº degrees latitude at the center of the earth, divides the earth into the Northern and Southern Hemispheres.
For the past 2.5 million years the climate of the Northern Hemisphere has fluctuated between conditions of warm and cold. These cycles are the result of changes in the shape of the Earthâs orbit and the tilt of the Earthâs axis. The colder periods allowed the expansion of glaciers that covered large parts of the Northern Hemisphere. Changes in climate have followed a regular pattern for the past 700,000 years. Each cycle lasted about 100,000 years and consisted of a long period of generally cooling climate during which glaciers grew, followed by shorter periods of conditions similar to or warmer than those of today.