Ecology of The Individual
Ecology is a branch of biology that deals with the interre-lationship of organisms among themselves and with their biotic (animate) and abiotic (inanimate) environment.
The study area of ecology is the ecosystem, which is the unity made up of the environment (biotope) and the living ecological community (biocenosis).
Biology – Ecology – Abiotic Factors: Light
Within the interrelations of an organism to its environment, one distinguishes between influences from the inanimate environment (abiotic environmental factors) and effects due to other organisms (biotic factors).
Abiotic factors are nonliving physical and chemical factors that affect the ability of an organism to reproduce and survive, for example temperature, water, and light. Biotic (or animate) factors, on the other hand, include predator-prey relationships, competition, symbiosis, and parasitism, among others. Depending on the type, individual environmental factors can have rather variable effects on the existence of an organism.
Graphically, this influence is usually illustrated with the aid of a tolerance curve. The section along the curve most favorable for an organism is called the optimum; the threshold values, within which an organism can exist, are called minimum and maximum. A tolerance curve also shows a section where an organism can still survive but is unable to reproduce (pessimum).
The tolerance range between minimum and maximum indicates the ecological potential of an organism for the respective environmental factor that is being considered. Species that have a narrow tolerance range are referred to as being stenoecious; species with a broad ecological potential are euryoecious.
The most favorable biotope is where the preference ranges intersect those environmental factors that are important for an organism.
This then limits the number of individuals of a species due to unfavorable environmental conditions (sphere of influence of environmental factors). For instance, water is usually the limiting factor for desert plants, while on the other hand, temperature and the availability of nutrient salts make growth for these plants still possible.
Light as ecological factor
The intensity and duration of solar radiation have a direct influence on plants and animals.
Plants require light as an energy source for photosynthesis; sun-adapted plants (heliophytes) require a lot of sun, while plants in shaded areas are better able to use any existing light. Light also plays an important role for many animals, for example, to initiate reproductive cycles or stimulate migratory movement in birds.
BASICS
INDICATOR PLANTS Plants can act as indicators of particular environmental conditions, for example, stinging nettle is an indicator plant for nitrogen-rich soil.