Ecology and Ecosystem: An Ovrview

  Author: Iloka Benneth Chiemelie
Publsihed 30th April

What is ecosystem?

An ecosystem in general terms comprises of the biological sphere present with a given locality, and the chemical and physical elements that define the non-living (also known as abiotic) environment (Ecological Society of America, n.d.). There are varied examples of ecosystems such as forest, grassland, pond, estuary etc. In the ecosystem, boundaries are not objectively defined, but in some cases they seem to be obvious as can be exemplified with the shorelines of a pond. In most cases, the boundaries established within the ecosystem are adopted for practical purposes in relations with the goals set in the study.

Studying the ecosystem normally feature the understanding of some processes that form a link between the living (biotic) with the features of the non-living (abiotic) environment. The field of is comprised with two major processes as energy transformation and biogeochemical cycling. As highlighted above, ecology does deal with the interaction of organisms with one another and the environment they exist in (Ecological Society of America, n.d.). Therefore, it is possible to study ecology on the individual, communal, populace, and ecosystem settings.

The individual study of ecology is focused mainly on the physiology, reproduction, behavior, and development, while the study of population is based on the habitant and the resources that the individual species require to exist, the behavior of the individual species in group, growth of the population and limitations to their abundance such as issues that result to extinction of the population (Gompper, 2002). The study of communities is based on understanding how the population does interact with other species such as interaction with predators, interaction with their own preys, competitions with other species that have shared needs or resources.

In the ecology of an ecosystems, all the above discussions are pulled together and the basic objective is to establish solid understanding of how the system as a whole operates. This implication is that instead of being focused primarily on a given specie, there is a need to focus more on the major aspects of the functionality of the ecosystem (Learner.Org, n.d.). This functional features comprises of things like the volume of energy produced through photosynthesis, how resources and energy flow along the different food chains, things that influence decomposition rate of a given material or the extent of nutrients that are being recycled within the ecosystem.

Constituents of an ecosystem

Major of people here on earth are already acquainted with the fragments of an ecosystem. In fact, it is impossible to identify anyone that is not directly or indirectly attached to a given part of the ecosystem. Whether it is the land people walk on, the water they drink, or the air they breathe, all these feature certain parts of the ecosystem. Thus, the parts of an ecosystem is classified as either being “biotic” or “abiotic” (University of Michigan, n.d.).

The biotic components of an ecosystem represents things that are living. They are things that can inhale and exhale. Thus, they are reproductive, and have a limited time for existence (at some point they are expected to die). They include primary producers – herbivores, carnivores, omnivores, detritivores, and the rest of them. On the other hand, abiotic represent non-living components of the ecosystem (University of Miami, n.d.). Their time is limitless and they are expected to exist as long as the ecosystem. They include sunlight, experienced temperature within a given locations, precipitation, water, moisture, soil and water chemistry etc. all these components of the ecosystem are very crucial (everywhere).

Normally, the biological communities comprise of a functional group. By functional group, it means a biological category that is made up of organisms normally perform similar features in the system. Example, all the plants that undergo photosynthesis or basic producers in the ecosystem creates a functional group. The defined membership of this functional group is not basically defined by who the player (that is to say “the specie”) is, instead it is influenced primarily by the functions that the player performs in the ecosystem (U.S. Geological Survey, n.d.).

Processes of ecosystems

The idea of how the ecosystem function sis illustrated by the figure (1) below. The function normally comprise of energy flows and cycle materials. Although these two routes are linked, it is important to note that they are not quite the same. 

Figure 1: processes of the ecosystem: energy flow and material cycle

Source as adapted from: (University of Michigan, n.d.)

The energy in the ecosystem is sourced from the sun as light or photon, and it is then converted into chemical energy which takes the form of organic molecules with the aid of cellular processes that comprises of photosynthesis and respiration before being finally converted into heat energy. Normally, energy is given away into the system (dissipated) as heat and once it has been lost, it cannot be recovered or reused. If the energy is not continually imported form the solar system, a quick short-down awaits the biological system. As such, the earth has been described as an open system that should offer due respect to the solar system as a source of its energy (U.S. Geological Survey, n.d.).

There are different ways through which elements like carbon, phosphorus, or nitrogen enter into living things. Understanding the process is crucial because plants comprises of elements that surround the atmosphere, soil or water. It is also possible for animals to directly acquire elements within the physical environment, but they typically obtain such from the consumption of other organisms (U.S. Geological Survey, n.d.). These elements are biochemically transformed within the bodies of organism, and they are returned into the inorganic state as a result of decomposition or excretion. Bacteria aid in the completion of the process through a decomposition or mineralization.

In the course of decomposition, it is important to note that these materials neither destroyed nor lost, which makes the earth a closed system with due respect to these elements (except for the exclusive case of meteorite that enter the earth). These elements are cycled within the ecosystem infinitely between their living and non-living states. Nutrients are the elements that their supply have the potential of limiting biological activities.

Energy transformation

In the ecosystem, the transformation of energy starts with the energy being derived from the sun. Photosynthesis is the process through which the sun’s energy is captured. When photosynthesis is taking place, carbohydrates (CHO) are produced as a result of carbon dioxide mixing with hydrogen (obtained from disassociation of water molecules). The energy obtained is then store within the high energy bond contained in adenosine triphosphate, or ATP.

According to prophet Isaah, “all the flesh is grass”, and this earned him the acronym as the first ecologist. This is because almost all the energy that are available for functionality of organisms are obtained from the plant. Since this is the first step when it comes to producing energy for the biotic environment, and this is referred to as primary production. Herbivores get these energy through the consumption of plants and other related plant products, carnivore eat the herbivores and the energy is transferred to them through such consumption, and detritivore feed on the droppings and carcass of the carnivores – getting their own share of the energy in the process.

Figure 2: Simple food chain

Source as adapted from: (University of Michigan, n.d.)

The figure (2) above is an illustration of a simple food chain, which shows energy being captured via the sun by plants during photosynthesis. This energy is transferred across the trophic levels through the food chain. Each of the trophic levels comprises of organisms that obtain their living through similar approach, which makes all of them either primary producers (i.e. plants), primary consumers (i.e. herbivores), or secondary consumers (i.e. carnivores) (Gompper, 2002).

At all stages of the trophic levels, dead tissues and wastages are produced. Detritivores, scavengers, and decomposers form a collective unit and consume all such wastes. It should also be noted that other animals such as beetles and crows also consumer fallen leaves and carcasses, however, it is the microbes that have the responsibility of finishing the decomposition process. Thus, it is not surprising that the amount of primary production is varied across locales as a result of differences in terms of how the solar system radiates and overall availability of nutrients and water within a given locale.

For a number of reasons, the transfer of energy through the food chain is considered in efficient. The implication is that a lesser amount of energy is accessible for the herbivores level when compared with the level of primary producers and the energy level decreases the more as the food chain decreases – which means that carnivores have the lowest availability of energy. This produces a pyramid of energy with the right implications that can be used to understand the extent of life that can be catered for with the available energy (Gompper, 2002).

Normally, when the idea of food chain is raised, people begin to visualize system of green plants, herbivores and the rest of them, they are actually known as grazer food chain, as they living plants are consumed directly. In many of the spheres, the primary source of energy is actually not the green plants as these energy comes from dead organic matters. This is referred to as the detritus food chains. Good examples comprises of the forest floors of woodland streams that exist in forested area, marsh of salts and the ocean floors across the very deep areas where most of the suns are extinguished above (Gompper, 2002).

In any case, while the main focus has been primarily on food chains, it is important to note that in the real setting, the biological system is more complex and actually impossible to be exemplified by a simple food chain. This is because there are numerous food links and chains within the ecosystem, but all the linkages are normally referred to food web. Food web is very complex because everything within the food web is also connected to something else, and it is necessary to understand to identify and understand the vital linkages within any given food web.

Biogeochemistry

When the question of how that one study which of these food web is more crucial, the obvious answer that one should study the flow of energy or how elements are cycled emerges. Take for instant, the cycling process of elements are contributed in some part by the organisms that store and transform the elements, and in some other aspects by the geology and chemistry existing within the natural world. Thus, the term biogeochemistry is described as the study of how living systems are controlled by and influence the chemistry and geology of the natural world. Therefore, the field of biogeochemistry covers many aspects of both the biotic and abiotic parts of the world (Ecological Society of America, n.d.).

Biogeochemistry adopts varied principles and tools when it comes to studying the systems of the earth. These principles and tools can be used to easily analyze majority of the issues and problems we face in the world now. Some of these problems are: global warming, acid rain, greenhouse gasses effects, and pollution. These principles and tools can be classified into three main components as: element rations, mass balance, and element cycling (Learner.Org, n.d.).

Element rations

Within the biological system, important elements are known as conservatives. They normally come in the form of nutrients. What is implied by conservatives are the organism that only experience slight change in the elements contained within their tissues if they are to maintain good health. The best way to conceive conservative elements is by linking them to other important elements within the organism. Take for instance, elements C, N, P, and Fe are found in healthy algae with the ration known as redfield ratio as described by the oceanographer that made the discovery (Learner.Org, n.d.):

C : N : P : Fe = 106 : 16 : 1 : 0.01

Once the ratio has been identified, it becomes easy to compare them with that measured in a given sample of algae with the aim of determining whether or not the algae lacks one of the identified limiting nutrients.

Mass balance

Mass balance is another vital tool in biogeochemistry and it adopts a simple mass balance equation as a means of describing the state of a given system. The system could be moneys, vegetables, oceans or the entire globe as a unit. With the aid of mass balance method, one can easily determine if the system is changing and the rate of such changes (University of Michigan, n.d.). This equation is given as:

NET CHANGE = INPUT + OUTPUT + INTERNAL CHANGE

From the above equation, net change is the change experienced in the system from a given point in time to the other and it is determined by the kind of inputs made, what the inputs are, and the recorded internal changes within the system. With acidification of lake as an example, the equation considers the level of inputs and outputs of acids, and the experience internal change of acids within the lake.

Element cycling

This offers the description of the locomotion of fast elements in a system in relation to where and how such movements are made. From earlier discussions, it can be seen that there are two basic kinds of systems that can be analyzed as: open and closed system.

A closed system is used to reference a system where the inputs and outputs are considered negligible in comparison with the experienced internal changes. Take for instance a system that include knife, or the entire universe (University of Michigan, n.d.). The cycling of materials from such system can be described in two ways within the closed system, or either by referencing the rate of movement experienced or the path that such movement is following.

• Rate = number of cycles / time * (as rate increases, productivity increases)
• Pathways – this is crucial as a result of different reactions that can potentially occur.

The open system contains input and outputs and also internal cycling. Therefore, it is possible to describe the rate of movement and the pathway that such movement followed in a similar way as adopted in the closed system above. It is also possible to define a new concept known as residence time. The residence time is used to reference on average, how long an element remains within a system before departing the system.

Rt = total amount of matter / output rate of matter

Established controls on functions of ecosystem

Considering that this paper has explained details of how ecosystems are designed and the flow of materials and energy via the ecosystem, the question of “what controls functions of the ecosystem?” can now be easily addressed. In terms of understanding what controls the ecosystem, two dominant theories exist. The first of such theories is the bottom-up control, which made it known that the nutrients supply available for the primary producer is the major control of how the ecosystem functions (Ecological Society of America, n.d.). The idea is that an increase in the nutrient supply will bring about a subsequent increase in the production of autotrophs, and the process is aided via the food web - which will trigger response from all other trophic levels in relation to subsequent increase in availability of food (ensuring that there is a faster cycle of energy and materials).

Top-down control is the second theory and it is based on the notion that predation and grazing that occur within the higher trophic levels on the lower trophic levels does control the functions of the ecosystem. Take for instance, the ecosystem experiences and increase in the volume of predators, there will be a resulting decrease in the volume of grazers, which will in turn bring about more primarily producers are the primary produces experience fewer consumption by the grazers. Therefore, the control of the population and the productivity process starts from the top level of the food chain when moving down to the bottom of the trophic levels (U.S. Geological Survey, n.d.).

These understanding raises normal question of which of the theory is correct? Well, the answer lies between the middle. This is because evidence exist from varied ecosystems researches that have studied both controls, nothing that both of the controls operate under the same degree but none of the controls is complete. This idea is based on the understanding that the top-down effect is more revealing trophic level closest to the top predators, but the control does weaken as one moves down the food chain. On a similar note, the bottom-up effects provides desired nutrients for stimulation of primary production, but there is lower stimulation for secondary production as the food chain rises above.

These two controls are present in any given system and at any given time, making it important that one should understand the absolute value of each control so as to be able to determine the expected behavior of an ecosystem under different circumstances – for instance, the case of climate change that the world is currently experiencing.

The geography of ecosystem

Different kinds of ecosystems abound such as – tundra and rain forest, coral reefs and ponds, desserts and grasslands. The difference in climate across location does determine the kind of ecosystem that is valuable within the location. The appearance of any given terrestrial system is normally influenced by the kind of vegetation that is dominant within such locality.

Biome is the word that is used to define the main vegetation present within a locale such as rain forest, tundra, grasslands and so on (University of Miami, n.d.). This extends over a huge geographical areas as illustrated in the figure (3) below. It is important to note that biome is never used to describe aquatic systems, as it is only used to reference vegetation that are dominant over a large geographic area, and this makes somehow broader in terms of mas when compared with an ecosystem.

Figure 3: Distribution of biomes

 Source as adapted from: (University of Michigan, n.d.)

It is good to note that the patterns of temperature and rainfall are distinctive across different locale. Although every local across the earth is offered the same volume of sunlight per annum (in terms of hours), it should be noted that they do not have the same volume of heat. This is because the rays of the sun are stroke directly in low latitudes and oblique in high latitudes. This differences in the distribution of heat across the universe sets up differences in temperatures, wind and ocean current – which in turn determine the volume of rainfall within a given locale. If one should combine this effect with the cooling properties of elevation and land masses on both temperature and rainfall, it can easily be seem that such will bring about a very complex pattern in the global climate.

Taking a schematic view of the earth in that flow, it can be seen that notwithstanding the complexity of the climate, numerous aspects can be predicted as illustrated in the figure (4) below. For instance, if higher solar energy strikes near the equator, it will create a nearly constant high temperature, high evaporation rate, and high transpiration of plants. Warm air are known to rise, cool and then shed its moisture – which creates the right condition for tropical rain forest. In contrary, a stable rain fall with varied temperature is a common site in Panama when compared with the comparatively endless precipitation accompanied with seasonal temperature changes as experienced in the New York. Each location has its own rainfall-temperature graph and it can be used to reference typical evidence from an even broader scale.

Figure 4: Influence of climate pattern on distribution of biomes

Source as adapted from: (University of Michigan, n.d.)

Necessary linkage can be made from plant physiology in relation to the fact that some plants grow under certain climates, which helps the appearance and vegetation known as biomes. This is illustrated in the figure 5 below. The below figure also demonstrates that certain climates are not possible (at least on earth). The available solar energy is not enough to power water cycle, which means that some of the water cycles are frozen throughout the year. This also means that it is also possible to maintain both a high tundra and a desert in the Sahara on the same planet (earth).

Figure 5: The distribution of the ecosystem in relation to temperature and precipitation.

 Source as adapted from: (University of Michigan, n.d.)

Conclusion

In conclusion, a number of discoveries have been made from this study. The first is that the ecosystem comprises of both living and non-living components, and they are crucial to almost all kinds of ecosystem. The ecology of ecosystem is focused on how energy is transformed and the biogeochemical cycling that occur within a given ecosystem. The ecosystem receives continuous input of energy from the sun as light, and some of these energy are lost as they are transferred to the trophic levels. On a different view, nutrients are recycled within the ecosystem, with their supply usually limiting biological activities. Thus, while energy flows, elements are known to cycle. A food web is the means through which energy is moved across the ecosystem, and the food web is made up of intertwining food chains. Energy is captured over photosynthesis and the volume of primary production controls the volume of energy obtainable across the trophic levels. Through biogeochemistry, one is able to study how chemical elements cycle through a given ecosystem, while the functions of the ecosystem is normally controlled with two major approaches as “top-down” and “bottom-up” control measures. A biome is an important type of vegetation that extends over a large areas.  The distribution of biome is largely determined by the patterns of precipitation and temperature that occur at the given locale.

References

Ecological Society of America. (n.d.). What does ecology have to do with me? Retrieved from Ecological Society of America: http://www.esa.org/esa/education-and-diversity/what-does-ecology-have-to-do-with-me/

Gompper, M. E. (2002, 8). The Ecology of Northeast Coyotes. Retrieved from New York, NY: Wildlife Conservation Society: http://www.wcs.org/media/file/Ecology_of_NE_Coyotes.pdf

Learner.Org. (n.d.). The habitable planet. Retrieved from Learner.Org: https://www.learner.org/courses/envsci/unit/pdfs/unit4.pdf

U.S. Geological Survey. (n.d.). Mineral Substances in the Environment. Retrieved from U.S. Geological Survey: http://geology.er.usgs.gov/eastern/environment/environ.html

University of Miami. (n.d.). ECOLOGY: The Study of Ecosystems. Retrieved from University of Miami: http://www.bio.miami.edu/ecosummer/lectures/lec03_climate.pdf

University of Michigan. (n.d.). The Concept of the Ecosystem. Retrieved from University of Michigan: http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/ecosystem/ecosystem.html