Living Environment

Definition of the living environment

Plants, animals, protozoa, and other organisms are known as biota. In order to survive, they interact with non-living elements that support life, known as the abiota, such as air, water, and soil. The living environment can be broken down into smaller ecosystems or environments.

Fig. 1: The living environment. A coral reef is a marine ecosystem where the living organisms correspond to the biosphere, the aquatic medium is part of the hydrosphere and the ocean crust and sediments correspond to the lithosphere (although the atmosphere is not visible here, it is interlinked to the other spheres, for example interchanging gases with the water)

Living environment examples

• Soils, rocks, etc., as the lithosphere.

• Seas, groundwater, etc., as the hydrosphere.

• Air, as the atmosphere.

• Animals, plants, etc., as the biosphere.

• Glaciers, ice caps, etc., as the cryosphere.

• Grasslands, deserts, artificial floating islands, etc., which combine any or all of the above.

Our living environments have been separated into these main spheres:

• The Atmosphere: the gas mixture surrounding the planet
• The Lithosphere: the crust and upper mantle, thus, the rocky layer of the planet
• The Hydrosphere: the water present on our planet in all its forms, including the Cryosphere (frozen water)
• The Biosphere: all living things.

The living environment's role and function

The roles and functions of our living environment are multifaceted. The presence of life on Earth has not only brought modifications to the climate but has also enabled our evolution.

Table 1: Some of the functions of the living environment with examples.

How the living environment came to be

Several hypotheses have been used to explain the origins of life.

According to the panspermia hypothesis, life may have been caused by extraterrestrial microscopic life carried onto Earth by falling space debris and meteorites.

Another theory is that life originated exclusively from the chemical reactions during the primordial exhalation of the Earth, which led to the production of amino acids and other organic compounds (abiogenesis).

The lithosphere as a living environment

Let's start with the Big Rock - the Earth's humble beginnings. Some 5 billion years ago, the earth began accumulating stellar materials and debris in its orbit.

Skip to 0.5 billion years later and the intense surface heat cause heavy metals to melt and aggregate into a core, which nowadays also sustains the magnetosphere.

We think that the Earth remained abiotic for another 0.7 billion years, until the first signs of life appeared in the form of bacterial communities. These communities were discovered in 3.7 billion-year-old rocks. At this point, the key was turned: Earth had become a living environment.

Future discoveries could change our definition and perception of what constitutes life and a living environment, and how we can identify them.

The atmosphere as a living environment

Up to about 2.2 billion years ago, the major atmospheric gases were carbon dioxide (CO₂), water vapour, and nitrogen (N₂). The first two were produced by volcanoes and evaporation from the oceans with the help of solar radiation (insolation). At the same time, water was maintained liquid by the atmospheric pressure of around 1 bar. This is about the same as on Earth today, which is approximately 1.013 bar.

As life developed, photosynthetic bacteria, followed by algae and plants, started to consume CO₂, sequestered or locked it in their cells, and then released oxygen (O₂) as a by-product¹.

In the past few centuries, the biggest gas-emitting sources have come from anthropogenic activities, especially from the utilization and burning of fuels. These fuels predominantly release CO₂, CH₄, and nitrous oxides (NO_x) into the atmosphere, as well as particulate matter (PM).

The hydrosphere as a living environment

Meteorites are often formed of or contain ice, and it is believed that they have brought significant amounts of water to Earth.

The Earth's orbital sphere is just the right distance from the sun to allow for liquid water, which is essential for all known life forms. Water on Earth also absorbs vast quantities of heat and heat-trapping gases like CO₂, helping keep global temperatures in check.

The hydrosphere can be defined by water acidity (pH), temperature, and cyclicity, and is also affected by anthropogenic activities such as introduced species, deliberate eradication or chemical runoff.

Water is abundant but uneven across the globe. This makes water resources highly valuable to industry (paint and coating manufacturers), agriculture (irrigation), domestic life (washing water) as well as wildlife (potable sources).

Living environment and health

The living environmental and its organisms health are linked because chemical energy flows constantly between producers (e.g. plants), consumers (e.g. plant-eaters) and decomposers. This is called a food chain, system, or web.

Sometimes, chemicals can accumulate in nature, through processes known as:

• bioaccumulation: usually accumulating in an organism over time through absorption.

• biomagnification: usually accumulating in an organism after predation.

Humans recognize the negative aspects of these processes, and institute laws to protect fauna, flora, fungi, etc. from harmful human activities or natural disasters.

• Conservation and management: IUCN Red List, The Wildlife and Countryside Act 1981

• Climate change adaptation: The Great Green Wall of Sahel³, Climate Adaptation Scilly⁴

• Climate change mitigation: Biodiversity Net Gain UK 2021⁵, the phasing-out of fossil fuel vehicles.

As well as:

• Breeding and releasing programmes: Bison Rewilding Plan

• Habitat creation: Endangered Landscapes Programme in the Southern Carpathians

All of this can be a lot to take in! Why not test your knowledge on some of the questions below:

The quality of our food, water, and air, all have a direct impact on our health and quality of life. Our food supply depends on healthy ecosystems. Our built environment has the capacity to influence life. Let’s see if you can answer the following question:

In its geologic history, both rapid and slow changes have occurred in the living environment. Rapid changes are typically correlated with extinction events, as they occur at rates faster than species can adapt. Species affected by such events can be grouped into:

• Keystone species: their disappearance affects the whole food web of a region, e.g. European rabbit O. cuniculus.

• Endemic species: found only in specific geographical areas, e.g. red grouse L. lagopus scotica.

• Highly distinct species or of commercial interest: often needing strong regulations to avoid over-exploitation, e.g. South African abalone H. midae.

Living environment standards

How or why would species be affected by a changing living environment and climate, one might ask?

There are certain environmental standards that need to be met for the biota to at least reach sexual maturity and reproduce, thus ensuring species continuation, and for the Earth's systems to maintain certain temperature, atmospheric, pressure, or humidity thresholds, or bring a cyclical quality to them. Some of the most important standards for life on Earth are:

• Water quality and availability (ex, impacted by human drainage)
• Light levels (ex. impacted by vegetation clearance)
• Gas levels, especially of oxygen and carbon dioxide (ex. impacted by eutrophication)
• Nutrient availability (ex. impacted by agricultural practices)
• Temperature (ex. impacted by concrete-covered ground)
• Natural disaster occurrence (ex. volcanism)

Living Environment and Biology

Biology is the science that studies living organisms, thus it deals with the biotic component of the living environment. Biology focuses on living beings typically at the organism level, while ecology and environmental science focus usually on levels above the organism level (as species, populations, interaction with other organisms and abiotic factors, etc).