The energy balance of the ecosystem.

Principles of differentiation Biogeocenology.

All ecosystems are affected by and interact with their environment. At the global scale, the Earth"s environment is characterized by the global energy balance, the balance of all heating and cooling terms that shape the climatic variations in space and time, especially with respect to surface temperature, precipitation, and light. From an energy balance viewpoint, the interrelationship between ecosystems and their environment are threefold: ecosystems utilize energy sources from their environment, and thereby are a part – though small – of the energy balance, ecosystem processes are affected by environmental conditions that are directly or indirectly connected to the energy balance (e.g. precipitation affects the levels of water limitation of terrestrial productivity) and the form and functioning of ecosystems affect energy balance terms. This article reviews the basics of the global energy balance, how it is reflected in the seasonal and geographic distribution of mean climatic properties, and how it interacts with life through ecosystem functioning.

The balance of nature is a theory that proposes that ecological systems are usually in a stable equilibrium (homeostasis), which is to say that a small change in some particular parameter (the size of a particular population, for example) will be corrected by some negative feedback that will bring the parameter back to its original "point of balance" with the rest of the system. It may apply where populations depend on each other, for example in predator/prey systems, or relationships between herbivores and their food source. It is also sometimes applied to the relationship between the Earth's ecosystem, the composition of the atmosphere, and the world's weather.

Introduction - What is an Ecosystem?

An ecosystem consists of the biological community that occurs in some locale, and the physical and chemical factors that make up its non-living or abiotic environment. There are many examples of ecosystems -- a pond, a forest, an estuary, a grassland. The boundaries are not fixed in any objective way, although sometimes they seem obvious, as with the shoreline of a small pond. Usually the boundaries of an ecosystem are chosen for practical reasons having to do with the goals of the particular study.

Biogeocenology the science dealing with interrelated and interacting complexes of living and inert nature (biogeocenoses) and their planetaryaggregate (the biogeosphere). The term “biogeocenology” arose in geobotany but has subsequently developed as a commonsubject of biological and geographical sciences, reflecting the interdisciplinary level of the study of living nature.

The founder of biogeocenology was V. N. Sukachev. In a number of works beginning in 1940 he defined the basic conceptsof biogeocenology, its theoretical and practical tasks, its ties with other sciences, and the program and direction ofresearch. An important role in the development of modern biogeocenology was played by the works of the Russianscientists V. V. Dokuchaev, G. F. Morozov, and R. I. Abolin, who established the idea of the interconnected quality of thephenomena of nature, and by V. I. Vernadskii, who discovered the enormous planetary significance of organisms (livingmatter). The questions under investigation in biogeocenology include research on the structure, properties, and functions ofthe components of the biogeocenosis and the deciphering of the mechanism of their relationships; study of the flows ofmatter and energy in them, as well as the proportion and form of the participation of their components in the material andenergy metabolism of the entire complex, and particularly in its biological productivity; study of the transformation by somecomponents of the states, properties, and functioning of other components; determination of their role in the change anddynamics of the biogeocenosis; determination of the reaction of the components and the biogeocenosis as a whole tospontaneous changes and the economic activities of man; study of the stability of biogeocenoses and their regulatorymechanisms; and research on the relationships and interactions both between adjacent biogeocenoses and between themore remote ones, which provide the unity of the biogeosphere and its major parts.

These problems can be solved only with the participation of a broad range of specialists (botanists, zoologists,physiologists, microbiologists, soil scientists, climatologists, biochemists, and others) in research. These problems requireextended periods of research, the use of experimentation (both under natural conditions and on models), the extensiveapplication of quantitative methods of study, and the use of mathematical analysis and statistical processing of the data. Asuccessful solution to the problems of biogeocenology determines the possible accuracy of the prediction of theconsequences of man’s interference in the course of natural processes, the possibility of directed regulation of therelationships and interactions of the components in the biogeocenosis in order to obtain the greatest and most generallybeneficial economic effect (chiefly a rise in biological productivity), and the choice of ways for the economic use of thematerial and energy resources of the biogeosphere and its parts. The significance of biogeocenology is particularly great forforestry and agricultural practice. It is also of high methodological significance for the study of man’s environment on theearth and for space science, the protection of industrial articles, food products, and feed from damage by the biologicalcomponents of the biosphere, the conservation of nature, and so on. Biogeocenology is closely related to landscapescience, soil science, climatology, biocenology, microbiology, and biogeochemistry.

Lecture 8.

Fulfillment of thermodynamic law of ecosystems.

1.Trophic structure of the ecological community

2.Producers, consumers, educenter

Now ecologists feel necessary to construct the theoretical building of system ecology, to break strong reductionistic tradition of ecology and to include the use of thermodynamics in a new holistic approach to study ecosystems, their structure, functioning and natural history. We tried to present here the current state of thermodynamic view on ecosystems.

The first law of thermodynamics proclaims constancy of the total energy of isolated system for all changes, taking place in this system: energy cannot be created or destroyed. According to the second law of thermodynamics in isolated system entropy is always increasing or remaining constant. All processes in the Universe are oriented to the equilibrium state. Nevertheless, biological systems, and, consequently, ecological systems create order from disorder, they create and support chemical and physical non-equilibrium state – the basis they live on.

In this chapter the general overview of ecosystem as thermodynamic system is given and the concept of Eco-Exergy is introduced. The use of this concept in ecology is demonstrated to be very fruitful. To make it easy for other researchers to use the Eco-Exergy the procedure of exergy evaluation for ecosystems is followed with special attention to dimensions used.

2. Community ecology, study of the organization and functioning ofcommunities, which are assemblages of interacting populations of the species living within a particular area or habitat.

As populations of species interact with one another, they form biological communities. The number of interacting species in these communities and the complexity of their relationships exemplify what is meant by the term “biodiversity.” Structures arise within communities as species interact, and food chains, food webs, guilds, and other interactive webs are created.

All biological communities have a basic structure of interaction that forms a trophic pyramid. The trophic pyramid is made up of trophic levels, and food energy is passed from one level to the next along the food chain (see below Food chains and food webs). The base of the pyramid is composed of species called autotrophs, the primary producers of the ecosystem. They do not obtain energy and nutrients by eating other organisms. Instead, they harness solar energy by photosynthesis (photoautotrophs) or, more rarely, chemical energy by oxidation (chemoautotrophs) to make organic substances from inorganic ones. All other organisms in the ecosystem are consumers called heterotrophs, which either directly or indirectly depend on the producers for food energy.

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Energy transfer and heat loss along a food chain.

Encyclopædia Britannica, Inc.

Within all biological communities, energy at each trophic level is lost in the form of heat (as much as 80 to 90 percent), as organisms expend energy for metabolic processes such as staying warm and digesting food (see biosphere: The flow of energy). The higher the organism is on the trophic pyramid, the less energy is available to it; herbivores and detritivores (primary consumers) have less available energy than plants, and the carnivores that feed on herbivores and detritivores (secondary consumers) and those that eat other carnivores (tertiary consumers) have the least amount of available energy.

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Figure 2: Transfer of energy through an ecosystem. At each trophic level only a small proportion of …