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Introduction to Ecology: The Biosphere A. Interactions and Interdependence 1. Ecology: the scientific study of interactions among organisms and between organisms and their environment 2. Biosphere: portions of the Earth in which all of life exists, includes land, water and air a) Ranges from surface to 8 km above and 11 km below Levels of Organization Biosphere The part of Earth that contains all ecosystems Biosphere Ecosystem Community and its nonliving surroundings Hawk, snake, bison, prairie dog, grass, stream, rocks, air Community Populations that live together in a defined area Hawk, snake, bison, prairie dog, grass Population Group of organisms of one type that live in the same area Bison herd Organism Individual living thing Bison Tissues, organs, Groups of and organ systems Cells Brain Nervous tissue Cells Nervous system Smallest functional unit of life Nerve cell Groups of atoms; smallest unit of Molecules most chemical compounds Water DNA Section 3-1 Producers 1. The Sun is the main energy source for life on Earth. – Less than 1% of all sunlight is used by living things. 2. Some organisms rely on the energy stored in inorganic chemical compounds (chemosynthesis) 3. Autotrophs can capture energy from sunlight or chemicals to produce food (plants, some algae and bacteria). a) Energy is used to combine simple inorganic compounds into complex organic molecules a) Resulting organic molecules combine and recombine to make living tissue. b) Photosynthesis: light energy used to power chemical reactions that convert CO2 and H2O into O2 and carbohydrates (such as sugar and starch) 1) Photosynthesis is responsible for adding oxygen and removing CO2 from the atmosphere. 2) Performed by plants, algae and some bacteria (ex:cyanobacteria) c) Chemosynthesis uses energy within chemical bonds of inorganic molecules to produce carbohydrates 1) performed by several types of bacteria Consumers 1. Heterotrophs rely on other organisms for their energy needs a) herbivores consume plants b) carnivores consume animals c) omnivores consume plants and animals d) detritivores consume organic remains and dead matter e) decomposers break down organic matter Feeding Relationships 1. Energy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food). Your body gets the energy and materials it needs for growth and repair from the foods you eat. 2. Food Chain: a series of steps in which organisms transfer energy through feeding Food Chains 3. Food Web: demonstrates the complex interactions between the organisms in food chains in an ecosystem. • The base of a food web is occupied mostly by vegetation (producers) and fine organic debris (decomposers). • Herbivores (primary consumers) and carnivores (secondary consumers) occupy the higher levels. • Omnivores occupy an intermediate level in the food web. 4. Trophic level: each step in a food chain or food web. D. Ecological Pyramids Shows the relative amounts of energy or matter contained within each trophic level. 1. Energy Pyramid a) Only ~ 10% of the energy in a trophic level can be transferred to the next level (can range from 0.05 to 20% b) The more levels that exist between a producer and a top-level consumer the less energy remains from the original amount. 2. Biomass Pyramid a) Biomass: the total amount of living tissue within a trophic level. b) represents the amount of potential food available for each trophic level 3. Pyramid of Numbers a) Based on the actual numbers of organisms at each trophic level. Energy Pyramids Energy Pyramid Shows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat. Biomass Pyramid Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid. Pyramid of Numbers Shows the relative number of individual organisms at each trophic level. III. Cycles of Matter A. Recycling in Biosphere 1. Matter is recycled within and between ecosystems. a) Biogeochemical cycles: connect biologic, geologic and chemical portions of the biosphere through the conversion of elements, chemical compounds and other matter between organisms and their environment. b) Matter can cycle because biologic systems do not use up matter – they transfer it into living tissue or pass it as waste products B. The Water Cycle 1. The process by which water is moved through the biosphere a) Evaporation: water changes to gaseous form by absorbing energy b) Transpiration: loss of water through leaves due to evaporation c) Condensation: changing of water from gas to liquid by releasing energy d) Precipitation: movement of water from atmosphere to surface as rain, snow, hail or sleet. • It is estimated that a single drop of water can take 4000 years to complete the water cycle. Water Cycle Condensation Precipitation Evaporation Transpiration Runoff Seepage Root Uptake C. Nutrient Cycles 1. Nutrient: chemical substances required for life functions and growth a) nutrients are passed between organisms and the environment through biogeochemical cycles 1) Prevents dangerous levels of nutrients (too high to too low) 2. Carbon Cycle Important because carbon is the key ingredient in all living organisms a) Less than 1% of all C on Earth circulates in the biosphere 1) ~ 71% in oceans as CO3 and Ca(CO3)2, 22% in fossilized carbon b) 4 main processes for carbon cycling 1) Biological processes (e.g.: photosynthesis, respiration, decomposition) 2) Geological processes (e.g.: volcanic outgassing, absorption in ocean/precipitation) 3) Mixed biogeochemical processes (e.g.: creation of fossil fuels, limestone) 4) Human activity (e.g.: mining, burning of fossil fuels and forests) Carbon Cycle CO2 in Atmosphere CO2 in Ocean Global Warming • Global warming is an observed increase in the average temperature of the Earth's atmosphere and oceans. • Part of this increase may be due to natural processes, and would have occurred independently of human activity. • The remainder is due to a human-induced intensification of the greenhouse effect. – The increased volumes of carbon dioxide and other greenhouse gases released by the burning of fossil fuels, land clearing and agriculture, and other human activities, are the primary sources of human-induced warming Greenhouse Effect • Greenhouse gases (GHG) are gaseous components of the atmosphere that contribute to the greenhouse effect. • The major natural greenhouse gases are water vapor (36-70% of the greenhouse effect); carbon dioxide (9-26%); and ozone (3-7%) 3. Nitrogen Cycle Important because N is used to make amino acids which are used to build proteins. a) Occurs in many forms, 78% as nitrogen gas (N2) 1) Ammonia (NH3), nitrate ions (NO3-) and nitrite ions (NO2-) from dead and decaying matter. b) Nitrogen fixation: conversion of N2 (gas) into NH3 by bacteria in soil or on legumes (roots of certain plants) 1) Decomposers further converted NO3- and NO2- ions which can be used by producers to make proteins. • C) decomposers return nitrates to soil as ammonia to be used again • D) soil bacteria convert nitrates into N2 (denitrification) Nitrogen Cycle N2 in Atmosphere NH3 NO3and NO2- 4. Phosphorus Cycle Important because used in DNA and RNA a) Not very common, found in rock and soil minerals and ocean sediments 1) Note that it is not found in the atmosphere b) As rocks and sediments erode, phosphate is released and may be dissolved in water 1) Used by marine organisms in the oceans 2) Some phosphate remains on land and cycles between organisms and the soil i) Plants absorb phosphate and bind it into organic compounds ii) Organic compounds move through the food web 5. Nutrient Limitation a) Primary productivity: rate at which organic matter is created by producers. 1) Depends on recycling of available nutrients – if any are in short supply it will limit an organisms growth. b) Limiting nutrient: a nutrient that is scare or cycles very slowly and limits growth in an ecosystem. 1) Fertilizer used to compensate for limiting nutrients (N,P and K) c) Oceans are (by their nature) nutrient-poor compared to the land. 1) Algal bloom: an increase in the amount of algae and other producers due to an increase of limiting nutrient(s). i) If there are not enough consumers, an algal bloom can upset the health of an ecosystem by oxygen depletion from bacteria during decomposition of dead algae.