Ecology is the study of the interactions of organisms with their living and nonliving environments. The word ecology comes from the Greek words oikos, meaning “home,” and logia, meaning “study.”
Ecologists study ecosystems. An ecosystem is the complete set of living and nonliving components of an area.
Ecologists study:
- the flow of energy through ecosystems, DESIGN MODELS OF FOOD WEBS AND ENERGY PYRAMIDS
- population dynamics, INTERPRET GRAPHS, CARRYING CAPACITY
- community composition, INTERDEPENDENCE, SYMBIOSIS, COMPETITION WITH SPECIES
- succession of species, CHANGE OVER TIME, PIONEER SPECIES, CLIMAX COMMUNITIES, KEYSTONE SPECIES
- the effects of disturbance, INVASIVE SPECIES, HABITAT DESTRUCTION, PLASTICS IN FOOD CHAIN
- evolution and coevolution, and biodiversity. GENETIC VARIETY
Ecosystems
The most fundamental principle of ecology is that no organism exists independently of other living and nonliving things around it. Every organism is part of an ecosystem. It draws energy and resources from its environment, and changes its environment by its own existence and death.
A tree in the middle of the park, for example, draws nourishment from the air and from the ground. It depends on sunlight for energy to grow. The tree may be home to birds, insects, and microscopic animals, and may serve as food for some of those organisms. The tree interacts with other trees and insects through the act of pollination, which is how plants reproduce.
Elements of the physical environment, such as air temperature and water, have an impact on the tree At the same time, the tree affects its physical surroundings. For example, it releases water vapor and oxygen to the air, changing the composition of the surrounding atmosphere. When the leaves fall off and die, the water and nutrients will return to the environment.
Energy, Productivity, Food Webs and the Flow of Energy
Ecologists are very interested in the flow of energy through ecosystems. The Sun is the source of almost all energy on Earth, and thus the source of all life.
Ecologists are very interested in the flow of energy through ecosystems. The Sun is the source of almost all energy on Earth, and thus the source of all life.
Green plants and algae capture the Sun's energy and use it to power photosynthesis, the process by which they convert carbon dioxide into sugars. Only plants and other photosynthetic organisms can do this; they do not need food because they make their own. For that reason, plants are called primary producers.
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Herbivores, plant-eating animals, eat plants and incorporate that stored solar energy into their own bodies. These are called primary consumers because they are consuming primary producers.
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Carnivores, meat-eating animals, eat other animals. They are called secondary consumers because they are consuming organisms that already consumed primary producers.
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When animals and plants die, their bodies are consumed by other organisms called decomposers, or detritivores (pronounced de-TRY-te-vorz). Decomposers include organism such as earthworms, maggots, fungi, and bacteria. These organisms break down dead tissues into their component molecules, allowing those nutrients to return to the environment and be used again.
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This process of taking energy from the Sun and moving it through plants, herbivores, and carnivores is called energy flow. It is also called a food chain, or a food web. Each step in the food chain is called a trophic level, from the Greek word trophikos, meaning “nutrition.”
The amount of living material (biomass) and energy in food chains has a specific ordering between trophic levels. For example, an African savanna ecosystem might consist of trees and grasses (primary producers), gazelles and zebras (primary consumers), and lions (secondary consumers). Primary producers have the most biomass, followed by primary consumers, and then secondary consumers.
The amount of energy at each trophic level will follow the same pattern. This ordering of trophic levels forms a pyramid with primary producers at the bottom followed by primary consumers in the middle and secondary consumers on the top. More energy is required at the lower levels of the pyramid because during the transfer between trophic levels energy is lost through heat and waste products.
The amount of energy at each trophic level will follow the same pattern. This ordering of trophic levels forms a pyramid with primary producers at the bottom followed by primary consumers in the middle and secondary consumers on the top. More energy is required at the lower levels of the pyramid because during the transfer between trophic levels energy is lost through heat and waste products.
Primary producers (plants, algae, and photosynthetic microbes) are the base of food chains and are the lowest trophic level. Primary producers thus make their own food and are called autotrophs; all other organisms ultimately use the energy produced by autotrophs and are called heterotrophs. At the next trophic level, primary consumers (herbivores) eat some of the sugars produced by primary producers. Secondary consumers (predators) consume primary consumers and other secondary consumers. Decomposers break down the carcasses of dead primary and secondary consumers and uneaten primary producers.
Words to Know
Autotroph
An organism that uses sunlight or chemical energy to produce its own food, such as a plant; autotroph means “self-feeder.”
Biodiversity
The variety of living organisms that exist within a given geographical region.
Biomass
Biological material derived from organisms that are still alive or were recently living, especially plants.
Carnivore
An animal that eats only or mostly meat.
Ecosystem
All of the living and nonliving components of a particular area, including organisms, sun, air, soil, and water.
Herbivore
An animal that eats plants.
Heterotroph
An organism that derives its energy from consuming other organisms or their body parts.
Photosynthesis
The process by which plants and algae use the Sun's energy to convert carbon dioxide and water into sugars.
Autotroph
An organism that uses sunlight or chemical energy to produce its own food, such as a plant; autotroph means “self-feeder.”
Biodiversity
The variety of living organisms that exist within a given geographical region.
Biomass
Biological material derived from organisms that are still alive or were recently living, especially plants.
Carnivore
An animal that eats only or mostly meat.
Ecosystem
All of the living and nonliving components of a particular area, including organisms, sun, air, soil, and water.
Herbivore
An animal that eats plants.
Heterotroph
An organism that derives its energy from consuming other organisms or their body parts.
Photosynthesis
The process by which plants and algae use the Sun's energy to convert carbon dioxide and water into sugars.
The Study of Ecology
Although mostly a biological subject, ecology also draws upon other sciences, including chemistry, physics, geology, earth science, mathematics, and computer science. As the impact of humans on the environment increases, the subject matter of ecology expands. Ecologists may be asked to decide whether a desert should be left in its natural state or opened to certain forms of human development. As a result, ecologists increasingly find themselves confronted with social, economic, political, and other nonscientific issues. Because it draws upon knowledge and information from so many disciplines, ecology is a highly interdisciplinary field.
The ultimate goal of ecology is to understand the nature of environmental influences on individual organisms, their populations and communities, on landscapes and, ultimately, on the biosphere, which includes all life on Earth. If ecologists can achieve an understanding of these relationships, they will be able to contribute to the development of systems by which humans will be able to wisely use ecological resources, such as forests, agricultural soils, and hunted animals such as deer and fish.
Take the Food Web Quiz below.
https://form.jotform.com/73106949299167
