GEEC-101-Chapter-2.1 (1).pdf

Chapter 2 Ecosystems: The Fundamental Design of Life ALJON M. BORABO Instructor I © The...

Chapter 2 Ecosystems: The Fundamental Design of Life ALJON M. BORABO Instructor I © The McGraw-Hill Companies, Inc LESSON OBJECTIVES At the end of this lesson, students should be able to: 1. Describe the components of an ecosystem 2. Differentiate between biotic and abiotic components and how they affect each other  ENERGY SOURCES IN BIOSPHERE ❑ Solar Energy – driving force ❑ Energy distribution and carbon dioxide in the atmosphere shape ecosystem and biosphere ❑ Biosphere energy and CO2 shape world climate and weather https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM ❑ An ecosystem is the basic unit of the field of the scientific study of nature. According to this discipline, an ecosystem is a physically defined environment, made up of two integral components: ❑ eco refers to a part of the world, and ❑ system refers to the https://healthylife.werindia.com/life-stages/kids- © 2011 Pearson Education, Inc. coordinating units nutrition/grow-your-garden ECOSYSTEM ❑ The simplest definition of an ecosystem is that it is a community or group of living organisms that live in and interact with each other in a specific environment. ❑ The living organisms of habitat and their surrounding environment function together as a single unit. ❑ The ecosystem is called as an ecological unit. https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM ❑ Charles Elton argued that ✓ organisms living in the same place not only had similar tolerances of physical factors in the environment, but also interacted with one another ✓ feeding relationships link organisms into a single functional entity, the biological community (food web). https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM ❑ Alfred Lotka came up with the idea of ecosystem and wrote in his book (entitled Elements of Physical Biology (1925): “the organic and inorganic worlds function in a single system to such an extent that it is impossible to understand either part without understanding the whole.” ❑ Ecosystem as an energy- transforming machine https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM ❑ Set of equations representing exchanges of matter and energy among components ❑ Characterize transfer of body mass using series of equations describing how system works https://healthylife.werindia.com/life-stages/kids- nutrition/grow-your-garden ECOSYSTEM ❑ In 1935, Arthur Tansley took Elton’s idea an important step further by considering organisms, together with the physical factors of their surroundings, as ecological systems. ❑ Ecosystem – fundamental unit of ecological organization ✓ Tansley envisioned the biological and physical parts of nature together, unified by the dependence of organisms on their physical surroundings and by their contributions to maintaining the conditions and composition of the physical world. ECOSYSTEM ❑ In 1942, Raymond Lindeman brought Lotka’s ideas of the ecosystem as an energy- transforming machine. ❑ Generalized lacustrine food- cycle relationships ❑ Lotka’s thermodynamics concept ❑ Elton’s food web concept ❑ Tansley’s ecosystem concept ECOSYSTEM ❑ Ecosystem is fundamental unit of ecology ❑ Within an ecosystem, energy passes through many steps or links in a food chain ❑ Each link in the food chain is a trophic (feeding) level ❑ Lindeman visualized a pyramid of energy within the ecosystem, with less energy reaching each successively higher trophic level ECOSYSTEM ❑ Single Channel Energy Flow Model ❑ Unidirectional flow of energy through different trophic levels, involving a single food chain and indicating dissipation of energy at each transfer ❑ Due to one way flow of energy, the entire system would collapse if primary source of energy were cut off ❑ Progressive decrease in energy due to loss of energy as heat in metabolic reactions ECOSYSTEM ❑ Single Channel Energy Flow Model ❑ About 1% of the total incident solar radiation is assimilated by the autotrophs into sugar ❑ Secondary productivity is about 10% at successive consumer trophic levels, although efficiency is higher at the secondary consumer level ECOSYSTEM ❑ In 1971, Eugene Odum, defined ecosystem as “Any unit that includes all of the organisms (i.e. the “community”) in a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles (i.e. exchange of materials between living and nonliving parts) within the system is an ecological system or ecosystem” ODUM EXTENDED HIS MODELS TO INCORPORATE NUTRIENT CYCLING ❑ Fluxes of energy and materials are closely linked in ecosystem function but ❑ Energy enters ecosystems as light and is degraded into heat ❑ Nutrient cycle indefinitely, converted from inorganic to organic forms and back again ❑ Studies of nutrient cycling provides index of energy fluxes ODUM EXTENDED HIS MODELS TO INCORPORATE NUTRIENT CYCLING Y-SHAPED OR DOUBLE CHANNEL ENERGY FLOW MODEL ❑ Shows a common boundary, light and heat flow as well as import, export and storage of organic matter. ❑ Decomposers are placed in separate box to partially separate the grazing and detritus food chain. ODUM’s “UNIVERSAL” MODEL OF ENERGY FLOW SOME REPRESENTATIVE ECOSYSTEMS ❑ Marine ecosystems comprise 75% of Earth’s surface and consist of three basic types: deep ocean water, shallow ocean, and ocean bottom. ❑ Phytoplankton, small photosynthetic organisms, suspended in ocean waters that perform 40% of all photosynthesis on Earth. SOME REPRESENTATIVE ECOSYSTEMS ❑ Freshwater (Standing) ecosystems occur on only 1.8% of Earth’s surface. That cover lakes, rivers, streams, and springs. ❑ Despite being small, they are diverse and support different kinds of animals, plants, fungi, protists, and prokaryotes. SOME REPRESENTATIVE ECOSYSTEMS ❑ Terrestrial ecosystems, are grouped into broad categories called biomes and are known for being diverse. ❑ A biome is a large-scale community of organisms, primarily defined on land by the dominant plant types that exist in geographic regions of the planet with similar climatic conditions. SOME REPRESENTATIVE ECOSYSTEMS/DIMENSION ❑ Macroecosystems are dimensionally larger systems, such as a forest or a lake. ❑ Micro-ecosystems are experimental set-ups in the field or laboratory built by life scientists and environmental biologists interested in evaluating the functional mechanisms of an ecosystem. It may be an aquatic or a terrestrial micro-ecosystem. Components of the Ecosystem ❑ Biotic components (aka biocenosis) include all living organisms and their products. ❑ These are in constant interaction and are, therefore, in a situation of interdependence. Components of the Ecosystem Components of the Ecosystem Components of the Ecosystem ❑ Transfer of energy from decaying matter to the higher trophic level, initially with the help of a detrivore. Components of the Ecosystem ❑ Abiotic components are the physical and chemical factors that act on living organisms at any part of their life, also known as ecological factors. NUTRIENT CYCLING Components of the Ecosystem ❑ Structural aspects are the components that make up the structural aspects of an ecosystem include: ❑ Organic compounds - protein, carbohydrates, lipids – links abiotic to biotc aspects ❑ Inorganic compounds ❑ Climate regimes – temperature, moisture, light, and topography ❑ Producers – plants ❑ Macroconsumers – phagotrophs (large animals) ❑ Microconsumers – saprotrophs, absorbers (fungi) Components of the Ecosystem ❑ Functional aspects are the components that make up the structural aspects of an ecosystem include: ❑ Energy cycles ❑ Food chains ❑ Diversity ❑ Nutrient Cycles ❑ Evolution