BIOLOGY Ecosystems

Ecosystems Consider a moose in the woods, moving through the spaces between trees. The moose feeds on shrubs, trees, and aquatic plants around a small pond. A beaver dam has formed the small pond. The animals, plants, and pond water are all part of a complex system of living and non-living things.

This complex system, made up of groups of living organisms and their non-living physical and chemical environment, is called an ecosystem. The components of an ecosystem are interrelated, which means that changes in one component can affect other components.

ECOSYSTEM all the living organisms in an area and their non-living environment interrelated – changes in one affects the others

For example, when a forest is cut down, the trees that were once home to insects, birds, and squirrels are no longer there. The animals will need to find a new place to live. Ecology is the study of how organisms interact with each other as well as with their environment.

ECOLOGY the study of how organisms interact with each other and their environment

PRACTICE 1. Which of the following are considered to be an ecosystem PRACTICE 1. Which of the following are considered to be an ecosystem? Explain your reasoning. (a) Pond yes (b) Schoolyard no (c) all the cats in your neighbourhood no (d) Tree yes (e) vase of cut flowers no

Living & Non-Living Factors Living organisms in an ecosystem are biotic factors. Biotic factors include organisms, their waste, their homes, and their remains. Insects, fungi, beavers, moose droppings, and shrubs are all biotic factors. BIOTIC FACTORS all living things and their remains insects, feces, nests, milk, ...

The non-living features of an ecosystem are abiotic factors The non-living features of an ecosystem are abiotic factors. This not only includes physical things, such as rocks, air, and water but also things that are measured such as air temperature, hours of daylight, and saltwater concentrations. ABIOTIC FACTORS the non-living chemical and physical characteristics of an ecosystem temperature, wind, water, minerals, ...

NOTE! It is the interactions of the biotic and abiotic elements that help keep ecosystems healthy and sustainable.

PRACTICE 2. Classify each of the following as either a biotic or abiotic feature: (a) Temperature abiotic (b) Wind abiotic (c) Sunlight abiotic (d) dead leaves biotic (e) Spiders biotic (f) Sand abiotic (g) Milk biotic (h) Hair biotic (i) Ice abiotic (j) Plastic abiotic

PRACTICE 3. “Human activities change only the biotic features of an ecosystem.” Is this statement true or false? Explain why or why not. false – we change both our abiotic environment (buildings, mining, …) and biotic environment (hunting, fishing, …) – both of which affect the ecosystem

PRACTICE 4. People living in northern environments are more likely to suffer seasonal affective disorder (SAD), which is a form of depression associated with low winter light levels. How is SAD an example of the relationship between the biotic and abiotic parts of an ecosystem? SAD is a form of depression (a biotic factor) associated with low light levels (an abiotic factor)

Populations & Communities In most ecosystems, there are many different species. A species is a group of similar organisms in an ecosystem. Members of the same species that live in the same ecosystem are a population. All the populations of different organisms in an area form a community. NOTE! Biodiversity is a term used to express the number of different types of organisms in an area. Typically, the more organisms there are the healthier the environment.

For example, the diagram below shows how ecosystems are composed of individual organisms, populations, communities, and the physical surroundings in which communities of organisms live.

SPECIES group of similar organisms POPULATION members of the same species that live in the same ecosystem COMMUNITY all living organisms, from all populations, that live in the same ecosystem BIODIVERSITY number of different types of organisms in area

PRACTICE 5. Does a population include abiotic features, biotic features, or both? Explain your choice. biotic (living) features only – species that live in the same ecosystem

PRACTICE 6. Would you consider a large city to be a population or a community? Explain your choice. community – all living organisms that live in the same ecosystem (i.e. humans, cats, dogs, rats, ...)

Differences in Ecosystems Ecosystems are highly variable. They can differ dramatically in size and in their biotic and abiotic features. We generally think of an ecosystem as a fairly large area, such as a forest or a lake. On a much smaller scale, the community of bacteria and fungi living in a rotting log is an ecosystem. In this way, large ecosystems may include many much smaller ecosystems.

Whatever the size, every ecosystem is characterized by a distinctive set of features. For example, you could describe a beaver pond ecosystem by its organisms or by its physical characteristics, such as the temperature range, or water depth.

Check Your Learning What abiotic factors may affect the growth of an oak tree in an Ontario forest? water, sunlight, temperature, pollution, ... (i.e. non-living factors)

2. A stream is an aquatic ecosystem, but it can also be part of a forest ecosystem at the same time. Explain how this is possible. it contains all the living organisms in the stream (fish, frogs, ...) and their non-living environment (rocks, water, ...) but the stream itself is part of a much larger forest ecosystem (deer, trees, mountains, ...)

Our planet has been referred to as Spaceship Earth Our planet has been referred to as Spaceship Earth. Explain how this might be an effective way to describe our planet. the spaceship (Earth) is flying through space – it has numerous inhabitants/passengers and has all the features necessary to support life