THERMAL FACTOR (TEMPERATURE)
Temperature is the degree of hotness or coldness of a substance. It is the most important ecological factor affecting almost all the metabolic activities of the Organism. Every physiological function has an optimum temperature at which it show the maximum metabolic rate. The vertical temperature gradient over Earth’s surface is called lapse rate. This value comes equal to 6.50C per 1000mElevation.Change in temperature is affected by factors like latitude, altitude, Topography, vegetation and slope. Temperature shows a great amount of variation altitudinally and latitudinally. The bacteria and cyanobacteria are known to survive even in thermal spring (60-900C) or permafrost (–30 to –500C) But most of the organisms are killed By higher temperatures due to denaturation of enzymes while others are killed By very low temperature due to freezing of body fluids except dry seeds, spores And cysts which have no water. Tolerance power to the extremes of temperature varies from species to species.
EFFECTS OF TEMPERATURE ON ANIMALS
Reproduction: In animals, the maturation of gonads and activity of spermatogenic tissue are also temperature dependent, which varies from species to species. In blow fly, Calliphora sericate, the number of eggs laid per Female, increases with increase in temperature upto 32.5(after which the number decreases. similarly, in chrotogonustrachypterus(an acridid insect),egg Laying increases from 25 to 300C.Thus,temperature also affects the fecundity(reproductive capacity)of animals. Similarly, an increase in temperature from 22 to 320C increases the egg laying about 20-30 times in Melanopussanguinipes.
Growth and Development: In Ostrea virginea, the length of body increases from 1.5 to 10.3 mm with an increase in temperature from 10 to 200C.
Thermoregulation and homeostasis: The birds and mammals have constant Body temperature and are called homeothermal or endothermic or warm blooded animals to deal with temperature extremes. This is achieved through evaporation of water from their bodies during summer and through Insulating action of fur, feathers, fats, etc.
EFFECT OF TEMPERATURE ON THE PHYSIOLOGY OF PLANTS
Transpiration: The rate of transpiration increases with rise in temperature. Extremely high temperature, if prolonged, may cause water stress to plants.
Vernalization: many species plants require low temperature treatment for seed germination and flowering, a phenomenon known as vernalization.
TEMPERATURE BASED ZONATION
Latitudinal zones: As many as six temperature-based terrestrial latitudinal zones are differentiated north of equator, each being characterized by specific vegetation type e.g. Snow, tundra, coniferous forests, deciduous forests, grasslands or deserts and tropical rainforests.
Altitudinal zones: As many as four temperature based terrestrial altitudinal zones are differentiated in Himalayas, each having specific vegetation type. Alpine (having Rhodendron, Juniperus),temperate (mainly conifers, oaks and Magnolia),tropical and subtropical zones (having mixed forests, bamboos, sal, etc.
Air in motion is called wind. Speed of wind is called wind velocity. It affects both plants and animals in following ways. Strong winds cause soil erosion so reducing soil fertility. These also cause Desertification by shifting of sand particles to fertile areas. These cause lodging (flattening of plants against the ground) of plants like Wheat, rice, maize, oat, sugarcane etc.
These help in pollination in the anemophillous gymnosperms(e.g. pinus) and angiospermic plants (e.g. cannabis).Unidirectional winds stimulate the development of flag trees (with branches directed on one side only on hill tops and sea shore, while many trees (e.g. pinus flexilis) become inclined.
Salt sprays: Wind, moving from sea to land, carries thin film of salt which is Sprayed on the coast vegetation. The plants resistant to this hypersalinity Shall survive while many plants die due to desiccation by exosmosis.