Ecosystems exist in a state of dynamic equilibrium. Changes occur as a constant part of the natural processes that sustain the balance between the biotic and abiotic elements of natural ecosystems. The state of dynamic equilibrium is a result of the frequently changing interrelationships between the four spheres.

There is usually a steadiness between producers and consumers in ecosystems. If a change occurs, it impacts on the entire food chain in the ecosystem.
Population size of a species at any one time is a result of a balance between growth factors (biotic potential) and decrease factors (environmental resistance).

All elements of ecosystems are interdependent. This interdependence makes ecosystems vulnerable. Changes in any of the elements will move an ecosystem beyond the state of dynamic equilibrium. The ability of ecosystems to deal with instability or alterations to the flow of air, energy, water and nutrients and return towards equilibrium is determined by their resilience.

Resilience is a natural function of ecosystems to adapt to the changes and restore equilibrium after a period of stress or change, either natural or manmade. The greater the degree of biodiversity is, the greater the resilience in that ecosystem.

Grasslands, in general, have a high resilience to fire and regenerate quickly. This is because their roots are underground. But grasslands can be ruined through overgrazing or ploughing up the roots of the grasses to plant crops.

Rainforests have high species diversity and high inertia, making them resistant to alteration or destruction. If a large enough area is cleared or degraded, however, the resilience of the ecosystem becomes so low that it may not recuperate. Nutrients stored in trees are no longer returned to the soil and the soils are quickly leached of any remaining nutrients. If clearing occurs on a large scale, the local climate may change and no longer support forests.

Mesopotamia is a land that lies along and between the rivers of the Euphrates and Tigris in western Asia. It is surrounded by the Anatolian plateau, the Iranian plateau, the Persian Gulf, and the Arabian and Syrian deserts. The name, Mesopotamia, comes from the Greek language, and means “land between the rivers.”

A city- state is a political unit that included a city and its surrounding lands and villages. Mesopotamia consisted of many independent city- states. Many of these were often ruined in wars, but two major city- states finally arose: Assyria in Upper Mesopotamia and Babylonia in Lower Mesopotamia.

The Sumerians were probably the first settlers of Mesopotamia arriving roughly at around 3300 B.C. They were responsible for the transition to an urban economy. The Sumerians had there own system of writing

To the Sumerians, religion was a very important factor. Like many other ancient peoples, they were polytheistic. They believed in many different gods. Each city built a ziggurat, a pyramid- temple dedicated to the chief god or goddess of an ancient Sumerian city- state. They used these building to worship their gods and goddesses. The Sumerians built these ziggurats using sun- baked bricks. People prayed and offered sacrifices of animals, grain, and wine to please the gods. They celebrated holy days with ceremonies and processions. Like Egyptians, Sumerians believed in afterlife. They saw the world as a gloomy place from which there was no release. Sumerians may have developed a pessimistic view of the world.

The Sumerians had invented the earliest from of writing by 3200 B.C. Their style of writing was known as cuneiform, from the Latin word cuneus for “wedge,” because it involved making wedge- shaped marks on clay tablets. Cuneiform came from the system of pictographs used by the priests.

The Middle East is a region of the world that will probably always have conflicts with its resources. These conflicts are based from survival and greed. Every drop of water and every inch of rich, fertile soil is important to the people so they can have a good economy. Water, oil, and land are the three main resources of conflict in the Middle East.

First, the countries in the Middle East are reliant on water as a main resource in their countries. The Middle East countries fight over water because it is very scarce in their area. The Middle East is surrounded by deserts and has hot climate with little vegetation. Countries fight over these water resources to help boost their economy. An example of a water resource that is that is causing problems in the Middle East is the Golan Heights water supply. One third of Israel gets its water supply from the Golan heights, and if they were to lose that supply of water, Israel’s economy would quickly drop.

Second, oil brings wealth to the Middle East which helps keep them economically stable. The Middle East is the number one producer of oil, in the world and if they were to lose that oil, the whole world would suffer. The United States has a large oil corporation which branches in Iran. The United States has made deals to pay Iran a small portion of money in order to have some control over the oil industry in Iran. Since oil is the century of the 20th century it will definitely cause conflict in the Middle East because it is so useful, and if they didn’t have the U.S. help they wouldn’t be as wealthy as they are from their oil.