Theory question 103
Population Ecology(a)(i) What is ecological succession? (ii) Describe the process of ecological succession on a bare plot of land.
(b) Explain the following terms: (i) biosphere; (ii) population; (iii) community; (iv) ecosystem.
(c) Name one instruments each used for measuring: (i) relative humidity; (ii) wind speed;
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(a)(i) Ecological succession is the gradual, orderly change in the species making up a community over time, until a stable climax community is reached.
(ii) Pioneer organisms such as lichens, algae and mosses colonise the bare ground; they break down rock and add humus, forming thin soil; grasses and herbs then grow, followed by small animals (insects, worms); shrubs replace them and shade out the grasses; larger animals (lizards, rats, birds) arrive; finally trees grow and a stable climax community (e.g. forest) is reached.
(b)(i) Biosphere: the part of the earth (land, water, air) where life exists.
(ii) Population: all the organisms of one species living in an area at a given time.
(iii) Community: all the populations of different species living and interacting in one area.
(iv) Ecosystem: a community of organisms together with its non-living environment, interacting as a unit.
(c)(i) Hygrometer (wet-and-dry bulb thermometer); (ii) anemometer.
Name the stages of succession in order, from pioneers to climax.