1. www.soran.edu.iq Ecology M. Saadatian Ecological factor in ecosystem 1

2. www.soran.edu.iq Ecological factor in ecosystem Ecological factors: Climate factor (sunlight, temprature,water,wind Edaphic factors (Soil). (mineral nutrition, acidity) Topography factors. (gravity, altitude, scope) Biotic factor (organism interactions) Climate factor: Light Temperature Water Wind Microclimate: the climate of a very small or restricted area, especially when this differs from the climate of the surrounding area. Macroclimate: The climate of a large geographic area

3. www.soran.edu.iq Light Intensity Quality Duration The intensity, quality and the duration of light play an important role for the survival of organism. The organisms have photoreceptors. The light may lead to many processes. The photosynthesis is performed by the autotrophs. The differentiation of tissues in plants requires light. It also affects the growth. The higher intensity of light produces internodes and leaves. These are smaller in size. The mechanical tissues and flowers are more in number. The lower intensity of light produces internodes and leaves which are larger in size. The mechanical tissues and flowers are few in number. The cells are large in size.

4. www.soran.edu.iq strong intensity of light= light yellow and red pigmentation moderate intensity of light = produces the bright green pigmentation The change in skin color occurs due to the change in intensity of light. It occurs in the animals as well as human beings. The frog and wall lizard look light in color when they appear in bright sunlight. In the sunset they appear dark in color. The animals are active in the different parts of day: Nocturnal (night): moths, owl and bats Auroral (day): rabbit vesperal (sunset): sparrows

5. www.soran.edu.iq The length of day plays an important role in the migration of bird, leaf fall, and dormancy of bud and the formation of new leaves. The decrease in day length leads to the leaf fall, bud dormancy and migration of birds The animal breeding is affected by the season and the photoperiodicity They can be short day, long day or neutral The short day animal includes the sheep and goats. The long day animal includes the ferrets and turkeys. The neutral animal includes pigs and squirrels.

6. www.soran.edu.iq Sun Angle, Duration, and Insolation Solar radiation received by the Earth system, known as insolation It is true that Earth’s atmosphere affects the amount of insolation received Heavy cloud cover, for instance, will keep more solar from reaching Earth’s surface than will a clear sky. However, cloud cover is irregular and unpredictable, and it affects total insolation to only a minor degree over long periods of time.

7. www.soran.edu.iq The amount of daylight controls the duration of solar radiation, and the angle of the sun’s rays directly affects the intensity of the solar radiation received. Together, the intensity and the duration of radiation are the major factors that affect the amount of insolation available at any location on Earth’s surface. a location on Earth will receive more insolation if (1)the sun shines more directly (2)the sun shines longer (3)both. The intensity of solar radiation received at any one time varies from place to place because Earth presents a spherical surface to insolation. Therefore, only one line of latitude on the Earth’s rotating surface can receive radiation at right angles, while the rest receive varying oblique (sharp) angle.

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9. Photoperiodism Photoperiodism is the physiological reaction of organisms to the length of day or night. photoperiodic effects relate directly to the timing of both the light and dark periods. Many flowering plants (angiosperms) use a photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night length, or photoperiod, which they take as signals to flower.phytochrome cryptochrome

10. www.soran.edu.iq obligate photoperiodic plants absolutely require a long or short enough night before flowering, whereas facultative photoperiodic plants are more likely to flower under the appropriate light conditions, but will eventually flower regardless of night length.

11. www.soran.edu.iq Long-day plants Long-day plants flower when the day length exceeds their critical photoperiod. These plants typically flower in the northern hemisphere during late spring or early summer as days are getting longer In the northern hemisphere, the longest day of the year is on or about 21 June (solstice). After that date, days grow shorter (i.e. nights grow longer) until 21 December (solstice). This situation is reversed in the southern hemisphere (i.e. longest day is 21 December and shortest day is 21 June).

12. www.soran.edu.iq Some long-day obligate plants are: Carnation (Dianthus) Henbane (Hyoscyamus) Oat (Avena) Ryegrass (Lolium) Clover (Trifolium) Bellflower (Campanula carpatica) Some long-day facultative plants are: Pea (Pisum sativum) Barley (Hordeum vulgare) Lettuce (Lactuca sativa) Wheat (Triticum aestivum, spring wheat cultivars) Turnip (Brassica rapa) Arabidopsis thaliana (model organism)

13. www.soran.edu.iq Short-day plants Short-day plants flower when the day lengths are less than their critical photoperiod. They cannot flower under long days or if a pulse of artificial light is shone on the plant for several minutes during the middle of the night Natural nighttime light, such as moonlight or lightning, is not of sufficient brightness or duration to interrupt flowering.

14. www.soran.edu.iq Some short-day facultative plants are: Hemp (Cannabis) Cotton (Gossypium) Rice Sugar cane Day-neutral plants Day-neutral plants, such as cucumbers, roses and tomatoes, do not initiate flowering based on photoperiodism They may initiate flowering after attaining a certain overall developmental stage or age, or in response to alternative environmental stimuli, such as vernalisation (a period of low temperature), rather than in response to photoperiod.

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