Our planet Earth is a remarkably complex system with millions of interactions between living beings and the elements of nature. It is so complex and vast that it is impossible to study Earth as a single entity . To distinguish the different systems that make up Earth, four subsystems have been defined: the biosphere, the geosphere, the hydrosphere, and the atmosphere.
The geosphere encompasses the solid part of the Earth, which includes the Earth's layers where we live and where rocks form. The geosphere is composed of several layers.
- The surface layer of the Earth, which usually varies between 500 and 1.000 meters, which is made up of soil and sedimentary rocks.
- The intermediate layer that corresponds to the continental crust where the plains, valleys and mountain systems are found.
- The lower basalt layer in which the oceanic crust is found and has a thickness of about 10-20km.
- The Earth's mantle.
- The Earth's core.
For more information about the Earth's layers, click on the link we just provided.
The atmosphere is the gaseous layer surrounding the Earth. It is composed of a mixture of nitrogen (78%), oxygen (21%), and other gases (1%). It is the zone where clouds and precipitation form, and its importance lies in making our planet habitable.
The hydrosphere is the part of the Earth occupied by liquid water. The liquid part includes oceans, seas, lakes, rivers, underground springs, etc. The solid part includes polar ice caps, glaciers, and ice sheets.
As you can see, each of Earth's subsystems is composed of different elements and plays a key role in life on the planet. But in this article, we'll focus on the biosphere. What is the biosphere?
The biosphere is the entire gaseous, solid, and liquid zone of the Earth's surface that is inhabited by living organisms. It is made up of areas of the lithosphere, hydrosphere, and atmosphere where life is possible.
Characteristics of the Biosphere
Now that you know what the biosphere is, let's look at its characteristics. The biosphere is made up of a thin layer of irregular dimensions. Since it's a system that encompasses all areas of the planet where life exists, it's more difficult to establish precise boundaries for where the biosphere begins and ends. But roughly speaking, the biosphere extends up to about 10 km above sea level and about 10 meters below ground level, where the roots of trees and plants penetrate and microorganisms exist.
In the marine part, it also includes surface waters and the ocean depths where life exists. Outside the biosphere and the limits we have more or less imposed, there is no terrestrial life.
As we've discussed, life in the biosphere isn't a continuous layer of animals, plants, and microorganisms (bacteria and viruses); rather, individuals belong to diverse species. These species (to date, there are more than two million known species) are distributed and occupy territory in different ways. Some migrate, others conquer new areas, and still others are more territorial and defend their habitat. If you'd like to learn more about biodiversity, you can explore different ecosystems found on the planet, such as beech forests.
The biosphere is an example of a system . We define a system as a set of components that interact with each other and with external agents, acting as a whole that maintains functionality within the environment. Therefore, the biosphere is perfectly defined as a system, since it comprises a set of species that interact with each other and, in turn, interact with other elements that do not belong to the biosphere, but rather to the geosphere, atmosphere, and hydrosphere.
In order to exemplify we turn to the elements, earth, water and air. Fish live in the hydrosphere, but in turn, in the biosphere, since it is in contact with liquid water and inhabits an area where life exists. The same goes for birds. They fly over the gaseous layer of the Earth called the atmosphere, but they also inhabit the areas with life belonging to the biosphere.
Therefore, the biosphere contains biotic factors , which are represented by all the communities of living organisms that interact with each other and with the rest of Earth's subsystems. These communities of living organisms are composed of producers, consumers, and decomposers. But there are also abiotic factors that interact with living organisms. These factors include oxygen, water, temperature, sunlight, and so on. The combination of these factors, both biotic and abiotic, constitutes the environment.
Levels of organization in the Biosphere
In the biosphere, living things generally do not live in isolation, but rather need to interact with other living things and with abiotic factors. This is why different levels of organization exist in nature. Depending on the interactions of living things and the size of the groups, we find populations, communities, and ecosystems.
Population
This level of organization occurs in nature when organisms of a particular species—plants, animals, or microorganisms—associate in a shared time and space. In other words, diverse species of plants and animals coexist in the same area and use the same resources to survive and reproduce. A clear example would be the diversity of species in a beech forest, where both flora and fauna can be found.
When referring to a population, it's necessary to determine the location of the species and the population's lifespan, as populations are not always sustainable due to factors such as food scarcity, competition, or environmental changes. Today, with human activity, many populations are disappearing because the nutrients in their environment are being polluted or degraded. Furthermore, in the context of pollution, it's important to read about climate change.
Biological community
A biological community is one in which two or more populations of living beings coexist. That is, each population interacts with the other populations and with the surrounding environment. These biological communities include all populations of organisms of different species that interact with each other. For example, a forest, a pond, etc., are examples of biological communities, since there is a set of populations of fish, amphibians, reptiles, algae, and sedimentary microorganisms that interact with each other and, in turn, interact with abiotic factors such as water (in respiration), the amount of light falling on the pond, and the sediment.
Ecosystem
The ecosystem is the largest and most complex level of organization. Within it, the biological community interacts with the abiotic environment to form a balanced system. We define an ecosystem as the set of biotic and abiotic factors in a given area that interact with each other. The different populations and communities that live in ecosystems depend on one another and on abiotic factors. For example, amphibians require insects for food, but they also need water and light to survive. We can also explore how ecosystems form on volcanic islands and in other regions.
The interaction between the biotic and abiotic environment occurs on numerous occasions in nature. When plants photosynthesize, they exchange gases with the atmosphere. When an animal breathes, when it feeds and then eliminates its waste, etc. These interactions of the biotic and abiotic environment translate into a constant energy exchange between living beings and their environment.
Due to the complexity of interactions, the interdependence of species, and the functions they perform, the extent of an ecosystem is very difficult to define . An ecosystem is not a single, indivisible functional unit but is composed of many smaller units, each with its own interactions and functions. To better understand this concept, you can consult this article on ecosystems.
In ecosystems, there are two closely related concepts, as organisms depend on them. First is habitat . A habitat is the place where an organism lives and develops. It comprises the abiotic physical area where the organism lives and the biotic elements with which it interacts. A habitat can be as large as a lake or as small as an anthill, as is the case with some frogs or insects.
The other concept related to the ecosystem is the ecological niche. This describes the role an organism plays in the ecosystem. That is, the way in which the organism interacts with biotic and abiotic factors. These organisms can be heterotrophs, scavengers, decomposers, and so on. One could say that the ecological niche is the profession or job an organism has within the ecosystem in which it lives.
As you can see, the biosphere is a very complex system with countless relationships that are essential for life on the planet. It is necessary to keep ecosystems free from pollution and degradation caused by our activities in order to maintain all the relationships among living beings. Each organism in the environment fulfills its own function, and this interplay of functions is what allows us to live in healthy conditions. That is why it is vitally important to protect and conserve our ecosystems so that we can continue to enjoy a good quality of life.
