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The term environment represents the space that surrounds someone or some thing; the set of chemical-physical factors (water, air, soil composition, light, temperature, ionizing radiation, pressure and gravity) and biological factors that act on living organisms and their development. By extension, the complex of social, moral, and cultural conditions that characterize human historical life; the people and things with which one is in contact.
In science and engineering, a system is the part of the universe that is being studied, while the environment is the remainder of the universe that lies outside the boundaries of the system. It is also known as the surroundings or neighborhood, and in thermodynamics, as the reservoir. Depending on the type of system, it may interact with the environment by exchanging mass, energy (including heat and work), linear momentum, angular momentum, electric charge, or other conserved properties. In some disciplines, such as information theory, information may also be exchanged. The environment is ignored in analysis of the system, except in regard to these interactions.
Environmental systems ecology (or Iandscape ecology) is a discipline that studies environmental complexity by analyzing the importance of the spatial relationships between the different components (individuals, populations, communities, environmental mosaics) of the real world. The environmental system, defined as the spatial representation of an ecosystem, is structured by the superposition of environments as they are perceived by different species or modified by ecological processes, such as floods and fires. The way in which an organism perceives the environment in which it lives is species-specific and we can therefore define a geobotanical, an animal and an anthropic environment. The complexity of environmental systems is addressed on a spatial scale through geographic information systems, and data are analyzed with geostatistical procedures integrated by the mathematics of fractals. Environmental systems ecology is applied primarily to the management of landscapes at the human scale and, in particular, to the assessment, management, and conservation of nature. It is in these fields that environmental systems ecology best transfers knowledge about the functioning of environmental mosaics.
The set of physical, chemical and biological factors that characterize that part of the planet called biosphere consisting of two thin layers, one above and the other below the Earth’s surface, and in which the life of organisms takes place. Each living species has particular environmental needs, reaching the optimum development around certain quantitative values of each factor. This means that the distribution of each species is determined by its range of tolerance to changes occurring in each environmental factor.
The organisms that can live and thrive within very large values of these factors (i.e. characterized by a tolerance range for that particular factor very wide) are called eurythermal, while those closely related to certain values (i.e. characterized by a tolerance range, for that particular factor, very narrow) and then practically to a few environments are said “steno-“. For example a stenothermic organism can tolerate only small variations of temperature. The fly is a eurythermic organism, as it can tolerate temperatures between 5 and 45° C. The adaptation to cold of the Antarctic fish Trematomus bernacchi is surprising: this organism is extremely stenothermic, being able to tolerate only temperatures between -2° C and +2° C. At +1.9° C this fish is prostrated by heat and remains motionless.
Environmental factors are divided into three types: limiting, triggering, and compensating. Limiting factors are those that exceed the limits of tolerance on the species and exert control over it. The importance of these factors is explained by some well-known laws in ecological studies: Liebig’s law of the minimum, according to which the growth rate of each organism is limited by any essential food, if it is present in extremely small quantities, and Shelford’s law of tolerance, which tries to establish the limits within which species can live (tolerance ranges). Triggering or trigger factors are those which, by entering an ecosystem, disturb its balance and trigger a chain reaction until a new balance is re-established. Compensating factors, on the other hand, are those that can replace each other: this is the case of species linked to a certain altitude in a certain latitude, which can live at a different altitude in other latitudes (taiga conifers and high mountain conifers of temperate or intertropical zones).
Against the variations of the limiting factors the organism reacts with a series of structural and physiological adaptations, including hibernation or aestivation and hibernation in Mammals, or with migrations, periodic if the factor that varies is periodic (lack of food, unfavorable conditions for reproduction, etc.).
The factors of the environment that are largely unrelated to living organisms, that is extrinsic to the biosphere, characterize the ecological area, while if you add to them the factors determined by animals and plants living in the area (complex of living that is called biocenosis) you have the so-called ecosystem. Biotope is the physical environment of the biocenosis and habitat is the set of biotopes in which a species can live.
The whole system of relationships of a species with the physical and biological environment is called niche; the environment of particular organisms in contrast with that of larger areas is called microenvironment. The environment should not be understood as something invariable in space and time, but must be considered as a dynamic entity, of which we can study the rate of change of each environmental factor, ie the gradients, the variations may be periodic in time (day and night, seasons, tides, lunar phases, solar cycles) or even geological duration.
The characteristics of the environment vary according to its physical conditions and geographical location. Therefore, the environment is divided into two basic types, the terrestrial environment and the aquatic environment, which in turn can be subdivided into epigeal environment and hypogeous environment, marine environment and freshwater environment, respectively. The marine environment includes the coastal environment, the pelagic environment, and the abyssal environment.
The study of the environment implies the knowledge of all the natural sciences: geography, geology, climatology, zoology, botany, genetics, ecology, paleontology, each of which analyzes the characteristics and develops specific classifications in relation to the importance of the object of investigation. The indications provided by the various naturalistic disciplines all converge in ecology, a science that considers the environment as a single entity together with the living organisms that inhabit it interacting with each other and with the environment, and that studies the changes in the environment in relation to the events that take place in it (see biome).
In the school of ethology the influence of the environment on behavior is generally recognized. Animals are continually subjected to a quantity of stimulations coming from outside and the experience of different environmental situations allows them, through learning, to acquire and retain information, on the basis of which they shape their responses to both internal and external stimuli in forms suitable to meet their needs in certain situations.
Some ethological schools believe that this influence joins, but does not replace, that of the genes. Other schools, however, support the total predominance of environmental influences on behavior, going so far as to deny any importance of the innate component. For the latter, at birth the animal is a tabula rasa and its behavior will be shaped entirely by experience.
The importance of phylogenetic adaptation of behavior, which is at the basis of the arguments of ethologists, is completely belittled by environmentalists, who argue that the influence of the environment is expressed only after birth and at the individual level, while for ethologists this influence coexists with that of natural selection which has operated and operates on genotypes, favoring those that have modules of innate behavior more suitable for survival.
A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale from microscopic to global in extent. It can also be subdivided according to its attributes. Examples include the marine environment, the atmospheric environment and the terrestrial environment. The number of biophysical environments is countless, given that each living organism has its own environment.
A natural environment includes all entities (living and non-living) and activities that occur naturally, or not artificially, within it. When the term is applied to the Earth or any of its parts, the environment includes the interaction of all living species, climate, and natural resources that influence the cycle of life. The concept of “natural environment” can be distinguished according to its components into:
complete ecological units that function as natural systems without massive civilized human intervention, including all vegetation, microorganisms, soil, rocks, atmosphere, and natural phenomena occurring within their boundaries and nature;
universal natural resources and physical phenomena without well-defined boundaries, such as air, water, and climate, as well as energy, radiation, electrical charge, and magnetism, not originated by civilian human actions.
The interrelated whole of the environment and the entire ecological community of organisms that inhabit it (including the organism to which the environment refers) defines what is called an “ecosystem.”
The term environment is also used in a broader sense not only in reference to a single organism, but to all organisms living on planet Earth. In this sense therefore it does not refer to a circumscribed area but to the whole planet and its particular characteristics that allow the existence of life.