The topic of human impact on the environment and ecology on life on the planet today is very relevant. More and more it is spoken about negative influence of human activity on the nature, global warming, threat of disappearance of some kinds of animals, pollution of the world ocean, etc.
We, being those who are not indifferent to all this, cannot but devote one of our articles to the environmental topic.
Below we will talk about how environmental factors can affect living organisms, which will help each of us to draw certain conclusions.
Instead of an introduction.
Despite the fact that the diversity of environmental factors is enormous, and the nature of their origin may often differ, there are such regularities and rules of impact of these environmental factors on living organisms, which are universal.
Whatever the environmental factor, it will affect living organisms as follows:
- Changes in the geographical distribution of species occur
- Changes in species fertility and mortality occur
- There’s a migration of species
- Species have adaptive qualities and adaptations
However, the factor will be most effective if its value is optimal for the body, not critical. The impact of the factor will affect absolutely all living organisms, including humans.
Regularities of the impact of environmental factors on organisms
Further we will consider the main regularities of the impact of environmental factors on organisms:
- Optimum rule
- Liebich Minimum Law
- Shelford’s tolerance law
First of all, it should be said that the result of the environmental factor depends on how intense it is. The most favorable range of impact is called the optimum zone, which guarantees normal life activity.
And if the action of the factor deviates from the optimum zone, there is a negative impact on the vital activity of the population of the species, i.e. the factor passes to the zone of oppression.
The minimum and maximum values of the factor are called critical points, outside of which the organism can no longer exist. The range of influence of ecological factor between critical points is a zone of tolerance of an organism in relation to the concrete factor.
If, for example, the effect of the factor is graphically displayed, then the point on the X-axis, which will correspond to the best indicator of the organism’s life activity, will be the optimal value of the factor or just the point of optimum.
However, it is very difficult to determine it, so more often than not the optimum or comfort zone is taken into account.
It follows from this that the points corresponding to the minimum, maximum and optimal parameters are cardinal points that determine the possible variants of the body’s response to a particular factor.
And if the environment is characterized by such conditions, where the factor or several factors go beyond the optimum zone and act on the body depressingly, it will be an extreme environment.
The presented regularities are the rule of optimum.
Liebich Minimum Law
In order to maintain the vital functions of living organisms it is necessary to combine the conditions of the environment in a certain way. For example, when the environment has all favorable conditions, except one, this one condition plays a decisive role in the life of a particular organism.
Taking into account the fact that it limits the development of the organism, it should be called a limiting factor. In other words, the limiting factor is the ecological factor with the value exceeding the limits of species survival.
Scientists have initially stopped that the development of living organisms is limited by the lack of a single element (light, moisture, mineral salts, etc.).
However, in the middle of the XIX century German organic chemist Eustace Liebich for the first time experimentally proved that the growth of plants is dependent on the component of nutrition, initially present in a minimum amount. This phenomenon is called the Liebich Minimum Law.
If we give this law a modern formulation, it will look as follows: the endurance of a living organism determines the weakest link in the chain of its ecological needs.
Shelford’s tolerance law
70 years after the Liebich Minimum Law was opened, it was established that the limiting effect was not only a lack but also an excessive factor (heavy rains ruin the harvest, the soil becomes infertile from fertilizer saturation, etc.).
This idea was introduced by the American zoologist Victor Shelford, who formulated the law of tolerance.
This law sounds as follows: the role of the limiting factor of the organism prosperity can perform both the minimum and maximum ecological influence, and the range between them indicates the limit of tolerance (the value of endurance) or ecological valence of the organism to a concrete ecological factor.
The principle of limiting factors is applicable to all types of living organisms: animals and plants, biotic and abiotic forms.
For example, competition between one species and another is a limiting factor; weeds, pests or insufficient population of another species are also limiting factors. However, based on the law of tolerance, if a substance or energy is present in the environment in excess, pollution begins.
As for the endurance limit of the organism, it is possible to measure it at the stage of transition from one stage of development to another, as often young individuals are more demanding and vulnerable than adults.
The most critical from the point of view of the influence of any factors is the period of reproduction, when many factors acquire the status of limiting factors.
It should also be noted that everything said before, regarding the endurance of the organism, was related to only one factor, but for wildlife is characterized by the combined action of all environmental factors.