Ecosystems Ecosystems: What Are They and How Do They Work?

The Basic Needs of Living Organisms 1. Water Water is needed to transport nutrients to cells and carry waste away. Evaporating water helps regulate body temperature in humans, and is necessary for key processes in plants. 1. Shelter Whether it is a house, leafy tree, or mossy lake bottom, organisms need shelter to protect them. These are the basic needs for most organisms on Earth, but not all.

4. Minerals Minerals are necessary for plant growth. Through the food chain, those nutrients are passes from plants to animals. 5. Food Organisms need food in order to live, grow, and reproduce. 6. Decomposers The organisms of decay (mainly bacteria and fungi) recycle sewage and dead plants and animals. 1. Air The earth’s air is a mixture of mainly nitrogen, oxygen, carbon dioxide and other gases. Nitrogen is required for building proteins and enzymes. Oxygen is required for the processing of food, and carbon dioxide is needed by plants for photosynthesis.

Levels of Organization Scientists classify matter according to size and function. There classification scheme is referred to as levels of organization. This system of organization will be useful to us as we discuss ecosystems.

ECOLOGY Ecology is the science that studies relationships and interactions in nature. An organism is any form of life. Species are organisms that are closely related. It also shows how organisms interact with one another and with their nonliving environment.

Species A species is a group of closely related organisms that can interbreed. There are thought to be approximately 3.6 – 10 million different species on Earth. Scientists have only identified, named, and described about 1.4 million species.

Populations A population is a group of the same type of organisms living in a certain area. Examples: All the sunfish in a pond The white oak trees in a forest The people in a country

Genetic diversity In most natural populations, individuals vary slightly in their genetic makeup, which is why they do not all look or act alike. This is called a population’s genetic diversity.

Communities vs. Ecosystems A community consists of populations of different species living and interacting in an area. An ecosystem is a community interacting with its physical environment of matter and energy.

Ecosystems An ecosystem includes living organisms and non-living substances interacting to produce an exchange of materials between the living (biotic) and non-living (abiotic) parts. Can range in size from a puddle of water, to a stream, to an entire forest. All of the earth’s ecosystems together make up the ecosphere (biosphere).

Ecosphere (Biosphere) The ecosphere, also known as the biosphere, is the total of all the various ecosystems on Earth.

Major parts of the earth 1. Atmosphere - the air around the earth 2. Hydrosphere - the water on the earth 3. Lithosphere - the earth’s crust and upper mantle 4. Biosphere - the portion of the earth in which living organisms exist and interact with their nonliving environment

Ecosystems consist of groups of organisms interacting in a variety of ways with each other and with the nonliving environment. The interactions within each ecosystem are unique to that ecosystem. Ecosystems consist of many communities living together in the same area.

The place or environment where a population (or an individual organism) normally lives is called its habitat. It may be as large as an ocean or as small as the intestines of a termite. All of the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce in its habitat, is called its niche.

The environment determines the boundaries of an ecosystem. As the environment changes (moisture, soil, temperature, wind) so does the ecosystem. Ecosystems are dynamic (changing) systems in which there is a constant movement of energy and materials. However, within this flow of energy, environmental resources and organisms tend to be in balance.

The sun is the source of radiant energy that supports the ecosphere. Solar radiation includes not only visible light, but also the rest of the electromagnetic spectrum. Energy

The radiation from the sun (ultraviolet, visible, and infrared energy) that reaches the atmosphere lights the earth during the daytime, warms the air, and evaporates and cycles water through the biosphere. About 1% of the incoming energy generates winds. About 0.1 % of the incoming energy is used for photosynthesis. About 70 % of radiant energy from the sun is reflected back into space.

Energy is transferred within the ecosystem, not only by radiation, but also by conduction and convection. Conduction is the transfer of heat within the ecosystem from a warmer substance to a cooler substance through direct contact. Convection is the transfer of heat in a fluid (liquid or gas) through currents within the ecosystem.