Colorful tropical fish swim through warm water around a coral reef. The fish are part of the coral reef ecosystem. Beautiful orchids grow on trees that tower above the rain forest floor. The orchids and the trees are part of the rain forest ecosystem. A hawk swoops down on a rabbit hopping through the tall grass of a prairie. The hawk, rabbit, and grass are part of the prairie ecosystem.
WHAT IS AN ECOSYSTEM?
An ecosystem is all the living and nonliving things in a certain area. All the plants and animals, even the microorganisms that live in the soil, are living parts of an ecosystem. Air, water, and rocks are nonliving parts of an ecosystem. It can be said to be a biological community of interacting organisms and their physical environment. An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere). Ecosystems are the foundations of the Biosphere and they determine the health of the entire earth system. Ecosystem is a biological community of interacting living things and their physical environment
Rainforest ecosystems are rich in biodiversity. This is the Gambia River in Senegal’s Niokolo-Koba National Park.
Ecosystems are smaller parts of all the living environments on Earth. Earth’s entire living environment is called the biosphere. The biosphere is made up of large areas called biomes. Land biomes include grasslands, deserts, coniferous forests (forests of cone-bearing trees), deciduous forests (forests of trees that shed their leaves), and tropical rain forests. There are also biomes in bodies of water, such as the ocean.
The biomes, in turn, are made up of many ecosystems. The desert biome, for example, covers all the deserts of the world. Each individual desert is an ecosystem. The Mojave Desert in California is a desert ecosystem.
In an ecosystem, each organism has its own niche or role to play. Consider a small puddle at the back of your home. In it, you may find all sorts of living things, from microorganisms to insects and plants. These may depend on non-living things like water, sunlight, turbulence in the puddle, temperature, atmospheric pressure and even nutrients in the water for life.
This very complex, wonderful interaction of living things and their environment, has been the foundations of energy flow and recycle of carbon and nitrogen. Anytime a ‘stranger’ (living thing(s) or external factor such as rise in temperature) is introduced to an ecosystem, it can be disastrous to that ecosystem. This is because the new organism (or factor) can distort the natural balance of the interaction and potentially harm or destroy the ecosystem.
Usually, biotic members of an ecosystem, together with their abiotic factors depend on each other. This means the absence of one member or one abiotic factor can affect all parties of the ecosystem. Unfortunately, ecosystems have been disrupted, and even destroyed by natural disasters such as fires, floods, storms and volcanic eruptions. Human activities have also contributed to the disturbance of many ecosystems and biomes.
Ecosystem goods and services is the extremely vital life-support services ecosystems provide to human life, its well-being and future economic and social development. For example: The benefits ecosystems provide include food, water, timber, air purification, soil formation and pollination.
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces (although some scientists say that the entire planet is an ecosystem). Energy, water, nitrogen and soil minerals are other essential abiotic components of an ecosystem. The energy that flows through ecosystems is obtained primarily from the sun. It generally enters the system through photosynthesis, a process that also captures carbon dioxide from the atmosphere. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.
Ecosystems are controlled both by external and internal factors. External factors such as climate, the parent material that forms the soil, and topography control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. Other external factors include time and potential biota. Ecosystems are dynamic entities—invariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance. Ecosystems in similar environments that are located in different parts of the world can have very different characteristics simply because they contain different species. The introduction of non-native species can cause substantial shifts in ecosystem function. Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops. While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other internal factors include disturbance, succession and the types of species present. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate. Biodiversity affects ecosystem function, as do the processes of disturbance and succession. Ecosystems provide a variety of goods and services upon which people depend; the principles of ecosystem management suggest that rather than managing individual species, natural resources should be managed at the level of the ecosystem itself. Classifying ecosystems into ecologically homogeneous units is an important step towards effective ecosystem management, but there is no single, agreed-upon way to do this.
WHY DOES AN ECOSYSTEM NEED PARTS?
Every living thing in an ecosystem depends in some way upon other living and nonliving things in the ecosystem. All the parts of an ecosystem work together.
The living things in an ecosystem are either producers or consumers. Producers do not eat other living things. Producers make food. Trees, grasses, and other green plants make food. Green plants are called primary producers. Plants use nonliving nutrients—nourishing substances, such as the chemicals in soil and water—to help them make food. They use energy in sunlight to make food. They also use carbon dioxide gas in air to make food.
Consumers are animals that eat other living things. Animals that only eat plants are called herbivores. Herbivores are primary consumers. Rabbits, mice, and plant-eating insects are primary consumers.
Animals that eat other animals are called carnivores. Carnivores are secondary consumers. Bears and hawks are secondary consumers.
Ecosystems also have decomposers. Decomposers break down dead plants and animals. They break down animal wastes. Fungi, such as mushrooms and mold, and bacteria are decomposers. They turn dead material and waste into chemical nutrients. Plants take up the nutrients with their roots. They use the nutrients to make more food.
HOW BIG IS AN ECOSYSTEM?
Some ecosystems are huge, and some are small. A tropical rain forest ecosystem might cover hundreds of square miles. A mangrove swamp ecosystem might stretch only a few miles along the shore of an island.
A place can have more than one ecosystem. A rain forest and a mangrove swamp could be on the same island. A coral reef ecosystem might be in the water around the island.
HOW DOES AN ECOSYSTEM WORK?
All things in an ecosystem are connected with one another. These connections come through food and energy. The energy comes from the Sun. Plants use the energy in sunlight to make food. Animals eat the plants. Other animals eat the plant-eating animals. The way energy flows in food from plants to animals is called a food chain. Food chains that overlap are called food webs.
Let’s look at an ecosystem in a forest. Water flowing in a river makes the riverbanks wet. Plants that need lots of water grow along the riverbanks. Insects feed on plants in or along the river. A salmon swimming by eats the insects that fall in the water. A brown bear that lives in the forest wades into the river and swipes its paw in the water. The bear catches and eats the salmon.
The bear tosses the salmon bones and some meat onto the riverbank. Bacteria and fungi now go to work. The tiny bacteria and fungi feed upon the remains of the salmon. They break down the salmon into chemical nutrients. Nutrients from the salmon go into the soil.
The roots of plants along the riverbank take up the nutrients. They use the nutrients to make food. In this way, nutrients get recycled back through the ecosystem.
WHAT CAN HARM AN ECOSYSTEM?
Any change in one living or nonliving part of an ecosystem can cause changes in other parts. Droughts, storms, and fires can change ecosystems. Some changes harm ecosystems. If there is too little rainfall, plants will not have enough water to live. If a kind of plant dies off, the animals that fed on it may also die or move away.
Some changes are good for ecosystems. Some pine forests need fires for the pine trees to reproduce. The seeds are sealed inside pinecones. Heat from a forest fire melts the seal and lets the seeds out.
Polluting the air, soil, and water can harm ecosystems. Building dams on rivers for electric power and irrigation can harm ecosystems around the rivers. Bulldozing wetlands and cutting down forests destroys ecosystems.
Ecologists are working with companies and governments to find better ways of catching fish, cutting down trees, and building dams. They are looking for ways to get food, lumber, and other products for people without causing harm to ecosystems.