Ecosystems Around the World PDF

Ecosystems around the World(text book pages 54-70) Objectives: To study about different ecosystems, a variety of habitats, bioaccumulation of toxins, bio- magnification and habitat survey.  Ecosystem All the living organisms in a place and the interactions between them and their physical environmen...

Ecosystems around the World(text book pages 54-70) Objectives: To study about different ecosystems, a variety of habitats, bioaccumulation of toxins, bio- magnification and habitat survey.  Ecosystem All the living organisms in a place and the interactions between them and their physical environment. Community Group of organisms of different species that live in the same habitat. Habitat A place where organisms live or shelter for the organisms. Population Total number of individuals of one species which live in one area. Factors affecting population: 1.Amount of space available for breeding(extinct) 2.Amount of food available (overgrazing) 3.Build up of waste products like toxins, insecticides or pesticides and bioaccumulation 4.Diseases 5.Predators 6.The physical environment(temperature changes, water availability, pH changes due to acid rain) What is Food Chain? Flow of energy in an ecosystem is one way process. The sequence of organism through which the energy flows, is known as food chain. The basic source of energy is sunlight. Important facts In a food chain each organism obtains energy from the one at the level below. Plants are called producers because they create their own food through photosynthesis Animals are consumers because they cannot create their own food, they must eat plants or other animals to get the energy that they need. Trophic levels in a food chain Producers Consumers (i) Primary consumers (ii) Secondary consumers (iii) Tertiary consumers (iv) Quaternary consumers Decomposers Grazing Food Chain  Significance of Food Chain The knowledge of food chain helps in understanding the feeding relationship as well as the interaction between organism and ecosystem. It also help in understanding the mechanism of energy flow and circulation of matter in ecosystem. It also helps to understand the movement of toxic substance and the problem associated with biological magnification in the ecosystem.  What is food web? Food web can be defined as, "a network of food chains which are interconnected at various tropic levels, so as to form a number of feeding connections amongst different organisms of a biotic community". It is also known as consumer-resource system.  Important facts A link or trophic level connects two nodes. Arrows represent links, and always go from prey to predator , energy flow. The lowest trophic level are called producers. The highest trophic level are called top predators. Movement of nutrients is cyclic but flow of energy is unidirectional and non-cyclic. Different food webs Soil food web Aquatic food web Food web in forest Food web of grassland Food web in terrestrial and aquatic ecosystem Food web in forest Grassland Food Web Food web of grassland Food web in terrestrial and aquatic ecosystem Significance of Food Web Food webs distinguish levels of producers and consumers by identifying and defining the importance of animal relationships and food sources, beginning with primary producers such as plants, insects and herbivores. Food webs are important tools in understanding that plants are the foundation of all ecosystems and food chains, sustaining life by providing nourishment and oxygen needed for survival and reproduction. The food web provide stability to the ecosystem. Energy is lost at each level in the food chain, as in the examples below. Energy lost through the process of respiration (as heat) Energy used up for movement (to search for food, find a mate, escape from predators…). Warm-blood animals (birds and mammals) maintain a standard blood temperature – they lose heat to the environment. Warm-blood animals lose heat energy in faeces and urine.  What are Ecological Pyramids? Ecological pyramids are graphical representations of the trophic structure of ecosystem. Trophic levels are the feeding positions in a food chain such as primary producers, herbivores, primary carnivore etc. Types of Ecological Pyramid Three types of ecological pyramids can usually be distinguished namely: Pyramid of numbers Pyramid of biomass Pyramid of productivity  Pyramid of Numbers It is the graphic representation of number of individuals per unit area of various trophic levels. Large number of producers tend to form the base. Lower numbers of top carnivores occupy the tip  Pyramid of biomass It is the graphical representation of biomass present per unit area at different trophic levels, with producers at the base and carnivores at the top. Biomass is calculated as, mass of each individual X no. of individual at trophic levels Leaves caterpillars small birds large birds On a small plant , the number of leaves are 10000 and mass of each leaf is 5g, 200 caterpillars with each having a mass 2g, mass of small bird is 40 g and the number is 3, mass of one large bird is 70g. Draw a pyramid of biomass. 5g X 10000 = 50000g leaves 2gX 200 = 400g caterpillars 40g X 3 = 120g small birds 70g X 1= 70g large bird  70g large bird 120g small birds 400g caterpillars 50000g leaves Pyramid of productivity or energy Pyramid of productivity is a graphical representation of the flow of energy through each trophic level of a food chain over a fixed time period. The input of solar energy may be indicated by adding an extra to the base. DECOMPOSERS: Are organisms that break down organic matter. Roles of decomposers: Examples of decomposers- Bacteria, fungi 1. Break down of complex carbon and nitrogen compounds into simple forms. 2. Recycle the nutrients. 3. Clean the environment.  Disturbances in ecosystem theBioaccumulation - When plants / animals take up a chemical from environment and do not excrete it , the chemical builds up in the organism over time to a potentially lethal level. inBiomagnification - Refers to the sequence of processes that results higher concentrations of the chemical in organisms at higher levels in the food chain. The concentration of the chemical may not affect lower levels of the food chain but the top levels take in so much it can cause disease or death. Extinction of species – Due to decrease in population of various species the balance of various tropic levels is disturbed as a result some levels have more accumulation of species while others have very less population.