UNIT 5

ECOSYSTEM

The term "ecosystem" was first proposed by Tansley (1935) as a name for the interaction system comprising living things together with their nonliving habitat.

Ecosystem is a complex of interacting plants and animals with their physical surroundings.

An ecosystem consists of plants, animals and microorganisms interacting with their physical and climatic environment in a given area.

Ecosystems are isolated from each other by boundaries, which confine and restrict the movement of energy and matter.

Ecosystems are defined by their boundaries, and depending on one’s perspective could be a pond, a small watershed, a major river basin, or even the whole biosphere.

Ecosystem structure is the physical elements and spatial arrangement of the living and non-living elements within an ecosystem.

Each ecosystem has its own set of species adapted to the regional climate, habitat type and disturbance patterns. Because species population changes in response to such biotic factor as food availability and predators, ecosystem also is constantly changing. One of the best examples of ecosystem is a forest ecosystem.

Healthy forest ecosystems are essential for the sustainability of forests. In a living system, normal functioning implies appropriate levels of health, vitality and productivity of the various components. Pollutants, fires, unfavorable climatic conditions, and infestations by insects and diseases often interact to stress forests. Measuring and reporting on the severity and the extent of disturbances and stress provide an important ecological measure of the condition, productivity and overall health of forest ecosystems.

Biological elements that strongly influence forest sustainability and conservation include levels of disturbance and stress, ecosystem resilience and extant biomass (biota).

Sources of disturbance and stress include insects, diseases, fires, pollutants, ozone and exotic pests. These sources may act alone or in concert to influence the development, structure and functioning of forest ecosystems. Climate change interacts with these disturbances to further impact on the condition and productivity of forests. Human activities also influence the condition and productivity of forests. Pollution, acting alone or in combination with other stressors, affects ecological system in general and forests in particular.

Maintaining the health and productivity of forests ecosystems is important for development of forestland.

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Notes on the text

confine - обмежувати, позбавляти свободи, ув'язнювати restrictобмежувати

perspective - 1) перспектива 2) вид 3) плани на майбутнє recognition - розпізнавання; визнання

watershed - вододіл, басейн ( річки) disturbanceпорушення

pattern - зразок, структура, схема, шаблон, візерунок spatial - просторовий

in response to – у відповідь на predator - хижак

sustainability - здатність до швидкого відновлення implу - мати на увазі, припускати, означати appropriate - властивий, відповідний

infestation - зараження паразитами measure - міра, ступінь, розмір, масштаб severity - суворість; жорстокість conservation - зберігання

resilience - 1) пружність, еластичність 2) здатність швидко відновлювати фізичні та душевні сили

extant - наявний, існуючий, збережений impact - вплив

in general – взагалі

Post-text exercises

I.Answer the questions:

1.What parts does an ecosystem consist of?

2.How is an ecosystem defined?

3.What is an ecosystem structure?

4.What does each ecosystem have?

5.What biological elements influence forest sustainability?

6.What do sources of disturbance and stress include?

1.Give definitions of the following words:

ecosystem restoration, habitat, ecosystem, ecosystem function, ecosystem sustainability, ecoregion

1.A continuous geographic area over which the macroclimate is sufficiently uniform to permit development of similar ecosystems on sites with similar geographical properties .

2.Actions taken to modify an ecosystem for the purpose of re-establishing and maintaining desired ecological structures and processes.

3.The capacity of an ecosystem for long-term maintenance of ecological

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