Part III Ecosystems

I. Read the text and explain the basic terms:

Ecologists invented the word ecosystem, an abbreviated from of ecological system, to describe a network consisting of organisms, their environment, and all of the interactions that exist in a particular place. In short, an ecosystem is an interdependent and dynamic (everchanging) biological, physical and chemical system.

To gain a better understanding of the ecosystem let us look at the two major components of all ecosystems: abiotic and biotic.

The abiotic, or nonliving, factors of an ecosystem are its physical and chemical components, for example, rainfall, temperature, sunlight, and nutrient supplies. Each of the earth’s many organisms is finely tuned to its environment and operates within a range of chemical and physical conditions, the range of tolerance. Although the range of tolerance is wide, most organisms thrive within a narrower range of conditions. This is called the optimum range. Outside this is the zone of physiological stress, where survival is possible, but difficult. Further outside the optimum range is the zone of intolerance, where an organism cannot survive.

The biotic components of an ecosystem are its living thing–fungi, plants, animals, and microorganisms. Organisms live in populations, groups of the same species occupying a given region. Populations are dynamic groups, changing in size, age, structure, and genetic composition in correspondence do changes in the environment. Populations never live alone in an ecosystem. They form a community. A community is defined as the organisms living within a given area. Within communities are many different Kinds of relationships-some cooperative, some not. One of the most familiar relationships is the predator-prey interaction. Another type of interaction is commensalism, a relationship between two species that is beneficial to one, but neutral (neither good nor bad) to the other. Mutualism is a relationship that is beneficial to both organisms.

Not all species interact in an ecosystem. This “unrelationship” is called neutralism. Seabirds on the coast of Louisiana and Texas, for instance, do not interact with songbirds living in nearby trees.

Some relationships can be harmful to one member. Parasitism is an example. Parasitism occurs when one species lives on or even inside another, called the host.

The final relationship worth noting is competition, a vying for resources between members of the same species (intraspecific) or between members of different species (interspecific).

In order to describe any organism it’s necessary to follow some principles. So if you asked an ecologist studying armadillos do describe them, she first tells you where armored minitanks live and then what they do. Where an organism lives is its habitat. Where it lives and how it fibs into the ecosystem are its ecological niche, or simply its niche. To describe an organism’s niche requires that we tell what eats it, where it lives, and how it interacts with other living and nonliving components of the ecosystem. But this is no easy task.

II. Study the vocabulary

1. habitat – родина (животного, растения)

2. niche – ниша

3. nutrient supplies – питательный

4. the rande of tolerance – уровень

5. thrive,v– процветать, преуспевать, буйно расти

6. intolerance – нетерпимость, невыносимость

7. the predator – взаимодействие хищник-жертва

8. beneficial – выгодный, полезный, целебный

9. neutral – нейтральный, беспристрастный, безучастный

10. tune,v – приспособлять

III. Match English and Russian equivalents

Экосистема abiotic factors

Неживые компоненты the range of tolerance

Пищевые запасы ecological system

Сфера терпимости nutrient supplies

Живые компоненты biotic components

Взаимодействие хищника и жертвы the predator prey interaction

IV. Insert the right words:

(abiotic, organisms, tolerance, physiological stress, biotic, populations, predator-prey)

1. The … factors of an ecosystem are its physical and chemical components.

2. Each of the earth’s many … is finely tuned to its environment and operates within a range of chemical and physical conditions, the range of ….

3. Outside this is the zone of … , where survival is possible, but difficult.

4. The … components of au ecosystem are its living things-fungi, plants, animals, and microorganisms.

5. Organisms live in … , groups of the same species occupying a given region.

6. One of the most familiar relationships is the … - … interaction.

V. Give the explanation for the following relationships:

VI. Define the main parts of the text. Make-up the plan.

VII. Retell the text according to your plan.

VIII. Using the text try o describe this scheme.