Notes: Energy in Ecosystems, Different Ecosystems and Environmental Succession • Sci.7.12B, Sci.7.8B and Sci.7.12D
What is an Ecosystem? • An ecosystem is composed of all the living and nonliving things that interact in a particular area. • All the living things within an ecosystem are called biotic factors. Organisms in an ecosystem interact with one another. They also interact with nonliving things. Plants, bacteria and animals are biotic factors. • The nonliving things within an ecosystem are called abiotic factors. Soil, temperature, water, oxygen level, carbon dioxide level, nitrogen level are abiotic factors.
Parts of an Ecosystem. • Every organism gets the resources it needs from their surroundings. Organisms live in specific environments that provides the things the organisms needs-this is called a habitat. • An ecosystem will have several habitats. A species is a group of similar organisms and will live in a specific habitat. • All organisms have a role to play within the ecosystem-this is its niche. An organism’s niche includes such things as: the type of food it eats, how it obtains this food, and the physical conditions that it needs to survive and reproduce.
Energy in Ecosystems. • An organism’s energy role is determined by how it obtains energy (food) and how it interacts with the other living things in its ecosystem. • An organism’s energy role in an ecosystem may be that of a producer, primary consumer, secondary consumer, tertiary consumer or decomposer. • Energy first enters most ecosystems from the sun.
Producers • Plants, some bacteria and algae (in aquatic environments) capture radiant energy from the sun. They capture the energy from sunlight and use carbon dioxide to create chemical energy in the form of glucose . Oxygen is also formed as a by-product. • Organisms that carry out photosynthesis are called autotrophs. They are considered producers because they produce their own energy. • Producers pass the energy from the sun along in the form of glucose to organisms which eat them.
The 3 types of consumers. • Organisms that cannot make their own energy are called heterotrophs. Heterotrophs get their energy from producers. • Consumers that eat only plants are called herbivores. Primary consumers are herbivores because they are the first to get the energy that plants captured from the sun. • Consumers that eat only animals are called carnivores. Secondary consumers can be carnivores because they will eat the animals which have eaten the plants, which captured the energy from the sun. • Consumers which eat secondary consumers are called tertiary consumers. Scavengers can be tertiary consumers because they are carnivores that feed on the bodies of dead organisms.
Decomposer • As the organisms in the ecosystem continue to take water, minerals and other raw materials from their surroundings-these materials begin to run out. When these materials run out new organisms will not grow. • Organisms create waste and eventually die. • Organisms that break down wastes and dead organisms and return the raw materials to the environment are called decomposers. Two major groups of decomposers are bacteria and fungi (molds & mushrooms). • Energy form the sun is transformed into chemical energy by producers. Consumers eat producers and pass that energy along from organism to organism until they die off where decomposers release that energy back into the environment. All along the amount of energy available to each energy level decreases.
Food Chains & Food Webs • A food chain is a series of events in which one organism eats another and obtains energy. The first organism in a food chain is always a producer. The second organism is a primary consumer. • A food web consists of many overlapping food chains in an ecosystem.
Energy Pyramid • When an organism eats food, it obtains energy. The organism uses some of this energy to move, grow, reproduce and carry out life processes. This means that only some of the energy will be available to the next organism in the food web. • A diagram called an energy pyramid shows the amount of energy that moves from one energy level to another. • Most of the energy in an ecosystem is available at the producer level. At each subsequent level there is less available energy. Only about 10% of the energy contained in one energy level of a food web is transferred to the next energy level.
Biomes • A biome is a group of ecosystems with similar characteristics • Different biomes will have different environments which will support different types of organisms.
A community is all the different organisms that live together in an area. A community in an ecosystem is in equilibrium, or a state of balance, when the numbers and species of organisms in it do not change suddenly. • Fires, floods, volcanoes and hurricanes can disrupt the equilibrium of a community by changing it drastically in a short period of time.
Ecological Succession • Communities sometimes change even without disasters. • Succession occurs when populations in a community change due to events in the environment. These changes may be sudden or they may happen very slowly • There are two main types of succession: primary and secondary
Primary Succession • Primary succession is the series of changes that occur in an area where no ecosystem previously existed-like a newly formed volcanic island or a bare rock. • The first species to populate this brand new area are called pioneer species. • Pioneer species are often lichens and mosses carried to the area by wind or water. Mosses and lichens can grow on bare rocks with little to no soil. As they grow they help break up the rock. When the mosses and lichens die they enrich the thin layer of soil with their nutrients.
Primary Succession • Lichen are a mixture of fungi and algae that have grown together. • Moss are a lot smaller than other plants and do not have true leaves or roots. • Overtime plant seeds land in the new soil and begin to grow. The type of plants that grows depends on the biome. • Eventually primary succession may lead to a community of organisms in equilibrium, which does not change drastically unless the ecosystem is disturbed. Reaching equilibrium can take centuries.
Secondary Succession • Secondary succession is the series of changes that occur after a disturbance in an existing ecosystem. • Natural disturbances that have this effect include fires, hurricanes, and tornadoes. Human activities such as farming, logging, or mining may also disturb an ecosystem. • Unlike primary succession, secondary succession occurs in a place where an ecosystem has previously existed. Secondary succession restores the ecosystem to a state in which equilibrium can be maintained. However the ecosystem may not be exactly as it was before the disturbance. • Secondary succession occurs somewhat more rapidly than primary succession.