Step out onto your school's playground and look around: there are ants, grass, rocks, sunlight, and a little wind. All of that, together with the relationships that form among those elements, makes up an ecosystem. Ecology is the science that studies how it works. At the end of the page we will come back to this playground to describe it in the language of ecology.
Biotic and abiotic components
If you lift a rock in a damp park, you will see earthworms, pill bugs, and roots in contact with dark soil, small stones, and cool air. How can we classify all the elements of that small corner of nature?
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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.
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.
Some species have a very narrow niche (specialists: for example, an animal that eats almost only one type of prey) and others have a broad one (generalists: they eat a bit of everything and live in varied environments). If their food runs out, specialists suffer more.
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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.
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.
In a forest, dry leaves fall and animals die every year, yet the soil is never buried under the remains and the trees never run out of minerals. How do living things divide up the tasks so that matter keeps circulating?
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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.
A prickly pear cactus planted in a very rainy jungle rots, and a fern from a shady spot wilts in hours in full sun. Why does each species thrive only under very specific physical conditions?
How to find out which factor is limiting
To find out which factor is limiting, you change only one and keep everything else the same. For example, for plants in the shade: make two groups of identical plants; give one group more light (with a mirror or by moving it) and the other more water, and measure their height every week. The group that grows more indicates the limiting factor. A group with no changes serves as a comparison (control).
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In a desert, plants are spaced far apart from one another. Identify which abiotic factor you think limits their growth and explain how this factor influences other…
In a desert, plants are spaced far apart from one another. Identify which abiotic factor you think limits their growth and explain how this factor influences other living things in the ecosystem.
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.
In a school ground, there is a very shady area where plants grow poorly. Propose a simple experiment to find out whether the limiting factor is light or water, stating…
In a school ground, there is a very shady area where plants grow poorly. Propose a simple experiment to find out whether the limiting factor is light or water, stating what you would keep constant and what you would measure.
Back to the beginning: on the playground, the ants (consumers) and the grass (producer) are biotic components; the rocks, the wind, and the sunlight are abiotic components that determine who can live there.
Summary
Let's practice! 3 medium exercises in this section