The Components of an Ecosystem
Step out into your school's yard and look around: there are ants, grass, rocks, sunlight, and a little wind. All of that, together with the relationships among those elements, forms an ecosystem. Ecology is the science that studies how it works. What role does each thing you see in the yard play?
Biotic and abiotic components
If you lift a rock in a damp yard, you will see earthworms, pill bugs, and roots in contact with dark soil, pebbles, and cool air. How do we classify all the elements in that tiny corner?
Classify the following elements of an ecosystem as biotic or abiotic: sunlight, an oak tree, air temperature, an earthworm, a rock, soil moisture, a mushroom, and wind.
Classify the following elements of an ecosystem as biotic or abiotic: sunlight, an oak tree, air temperature, an earthworm, a rock, soil moisture, a mushroom, and wind.
From the following elements of a marine ecosystem, state which are biotic and which are abiotic: the water, an alga, the salinity, a dolphin, a rock on the seabed, and…
From the following elements of a marine ecosystem, state which are biotic and which are abiotic: the water, an alga, the salinity, a dolphin, a rock on the seabed, and the light passing through the water.
An aquarium with fish, aquatic plants, a filter that oxygenates the water, and a lamp is a small artificial ecosystem. Identify its biotic and abiotic components and…
An aquarium with fish, aquatic plants, a filter that oxygenates the water, and a lamp is a small artificial ecosystem. Identify its biotic and abiotic components and describe a relationship that occurs between them.
Habitat and ecological niche
Think of your address and your job: the habitat is the species' "home address" and the niche is its "profession."
A woodpecker lives in a pine forest, where it excavates its nest in tree trunks and feeds on insect larvae living under the bark. State its habitat and describe its…
A woodpecker lives in a pine forest, where it excavates its nest in tree trunks and feeds on insect larvae living under the bark. State its habitat and describe its ecological niche.
Explain the difference between habitat and ecological niche using the example of a squirrel that lives in an oak wood and feeds on acorns.
Explain the difference between habitat and ecological niche using the example of a squirrel that lives in an oak wood and feeds on acorns.
Look at the diagram: two species of birds, A and B, live in the same holm oak tree. Bird A feeds on acorns in the canopy, and bird B feeds on insects living on the…
Look at the diagram: two species of birds, A and B, live in the same holm oak tree. Bird A feeds on acorns in the canopy, and bird B feeds on insects living on the trunk. Do they share a habitat? Do they share an ecological niche? Justify your answers based on the diagram.
Some crabs live buried in the wet sand of a beach and come out to feed on organic remains when the tide goes out. State their habitat and their ecological niche, and…
Some crabs live buried in the wet sand of a beach and come out to feed on organic remains when the tide goes out. State their habitat and their ecological niche, and name one abiotic factor that determines their activity.
Producers, consumers, and decomposers
In a forest, tons of dry leaves fall and animals die every year, yet the soil is never buried and the trees never run out of minerals. How do living things divide up the tasks so that matter never stops circulating?
Photosynthesis, the basis of producers
Producers carry out photosynthesis: using the energy of light, they transform carbon dioxide and water into glucose and release oxygen. It takes place in the chloroplasts, which contain chlorophyll.
$$\text{CO}_2 + \text{H}_2\text{O} \xrightarrow{\text{light}} \text{C}_6\text{H}_{12}\text{O}_6 + \text{O}_2$$(The equation is simplified: it is not balanced.) Light, water, and CO₂ are abiotic factors; glucose is the food that sustains almost all other living things.
Grass, horses, vultures, and fungi live in a grassland. Classify each organism as a producer, a consumer, or a decomposer.
Grass, horses, vultures, and fungi live in a grassland. Classify each organism as a producer, a consumer, or a decomposer.
A temporary pond dries up every summer. Explain how this abiotic factor affects the living things in the pond and cite one adaptation that one of its plants might show.
A temporary pond dries up every summer. Explain how this abiotic factor affects the living things in the pond and cite one adaptation that one of its plants might show.
In a natural park, the Iberian lynx and the red fox coexist in the same Mediterranean scrubland environment. The lynx hunts almost exclusively live rabbits by stalking…
In a natural park, the Iberian lynx and the red fox coexist in the same Mediterranean scrubland environment. The lynx hunts almost exclusively live rabbits by stalking among dense vegetation, whereas the fox consumes small rodents, carrion, fallen fruit, and insects in both dense and open areas. a) Identify, with reasoning, the habitat of both species and compare their ecological niches, indicating which is a specialist and which is a generalist. b) If an epidemic reduces the rabbit population by 90 %, predict what will happen to the population of each species and justify which one is more likely to survive based on the breadth of its ecological niche.
Abiotic factors shape life
A cactus planted in a rainforest rots, and a fern that lives in the shade withers within hours in full sun. Why does each species thrive only under certain specific physical conditions?
Humidity, temperature, and evapotranspiration
Plants absorb water through their roots and lose much of it as vapor through their leaves (transpiration); in addition, the soil dries out by evaporation. Together, these two losses are called evapotranspiration.
When water evaporates, it carries heat away: that is why a place with many plants stays cooler and more humid. In a city with asphalt and little vegetation, there is almost no evapotranspiration: the environment is drier and hotter (the "heat island" effect). So humidity and temperature are linked to each other.
Light and oxygen in water: they change with depth
In the sea or in a reservoir, such as the Sabana Yegua dam, abiotic factors are not the same everywhere. They vary from the surface to the bottom.
-
Light is gradually absorbed as it passes through the water. Near the surface there is a lot; a few meters down there is little, and in the deep bottom there is total darkness. That is why algae and aquatic plants (producers) can carry out photosynthesis only in the lit upper layer.
-
Dissolved oxygen enters from the air at the surface and is released by the photosynthesis of algae. In the upper layer it is usually plentiful. Below, where there is no photosynthesis and decomposers use up oxygen as they break down remains that sink, oxygen decreases and can even run out.
-
Temperature and pressure also change: the deep bottom is colder and under more pressure than the surface.
This explains why most fish and producers live near the surface, and why few organisms live in the deep bottom, adapted to darkness, cold, and pressure.
Define what an abiotic factor is and give three examples found in a marine ecosystem.
Define what an abiotic factor is and give three examples found in a marine ecosystem.
On the bare rocks of high mountains, only mosses and lichens grow. Identify two harsh abiotic factors of that environment and reason why these organisms are able to live…
On the bare rocks of high mountains, only mosses and lichens grow. Identify two harsh abiotic factors of that environment and reason why these organisms are able to live there.
Compare the abiotic factors that limit life on the deep seafloor with those that limit it at the sea surface, citing at least two differences.
Compare the abiotic factors that limit life on the deep seafloor with those that limit it at the sea surface, citing at least two differences.
After clear-cutting a forest plot, it is recorded that the average soil temperature has increased by 7.5 °C and surface moisture has decreased by 40 % compared to the…
After clear-cutting a forest plot, it is recorded that the average soil temperature has increased by 7.5 °C and surface moisture has decreased by 40 % compared to the adjacent intact area. A technical report states that "these abiotic changes will only affect the felled trees, but not the rest of the living organisms in the soil". a) Refute the report's statement by explaining how the temperature change and desiccation directly affect decomposers (bacteria, fungi, and earthworms). b) Predict the cascading consequences that the loss of these decomposers will have on nutrient recycling and the forest's ability to regenerate naturally.
The construction of a dam permanently floods a scrub-covered river valley, creating a 30-meter-deep reservoir. a) Explain how two essential abiotic factors (sunlight…
The construction of a dam permanently floods a scrub-covered river valley, creating a 30-meter-deep reservoir. a) Explain how two essential abiotic factors (sunlight penetration and dissolved oxygen availability) will vary from the surface to the bottom of the reservoir, justifying in which zone aquatic photosynthetic producers will be able to establish themselves. b) During the first two years, submerged terrestrial plant biomass rots at the bottom. Predict the impact this biotic process will have on oxygen concentration in the deep layers and the consequences it will bring for the first fish and benthic organisms that colonise the site.
In a large city, asphalt and buildings retain heat and the lack of vegetation reduces evapotranspiration, raising the average temperature by 2.5 °C compared to the…
In a large city, asphalt and buildings retain heat and the lack of vegetation reduces evapotranspiration, raising the average temperature by 2.5 °C compared to the surrounding countryside (heat island effect). a) A study reveals that trees in urban parks bud and bloom three weeks earlier than those in the countryside, but pollinating insects emerge at their usual time. Predict the impact this mismatch will have on plant reproduction and on urban insectivorous bird populations. b) A municipal project proposes replacing the trees in a town square with artificial turf to "reduce water consumption and keep the square cool". Scientifically refute this idea by explaining what abiotic function living plants perform that synthetic turf is unable to replicate.
Back to the beginning: in the yard, the ants (consumers) and the grass (producer) are biotic components; the rocks, the wind, and the sunlight are abiotic factors that determine who survives there.