Ecosystems

1. Ecosystems Components, Energy Flow, and Matter Cycling

2. Have You Thanked the Insects Today? • Their benefits to humans • Pollinators – fruits • Prey on other insects (free pest control) • Disappearance of insects (especially bees) would lead to extinction of all animals • Evolved 400 million years ago • First to invade the land and later the air • Most abundant and diverse group • Can rapidly evolve and develop resistance to pesticides • Use of pesticides kills large numbers of beneficial insects and arachnids • Learning the roles of insects helps us understand interactions

3. Nature of Ecology • What is ecology? • oikos – house, place to live • logos – study • The study of the connections in nature • What are organisms and species? • Organism is any form of life – unicellular or multicellular • Cell – basic unit of life • Prokaryotic • Eukaryotic • Species – any group of similar organisms that are able to interbreed and produce fertile offspring

4. What is a population? • Population is a group of similar species interacting with each other • Genetic diversity • Look and behave alike • Dynamic groups that change in: • Size • Age distribution • Density • Genetic composition • Live in a similar habitat

5. What are communities, ecosystems, and the biosphere? • Biological community – a complex interacting network of populations interacting with each other • Ecosystems – groups of communities • Range in size from a puddle to a desert • Man-made like cropfields, ponds, reservoirs

6. The Earth’s Life Support Systems • What are the major parts of the Earth’s life-support systems? • Atmosphere which is composed of several layers: • Troposphere (up to 11 miles up) • composed mainly of 78% N, 21% O, • Stratosphere (from 11-30 miles up) • Ozone layer is found just above the tropopause • Mesophere – (above 30 miles to about 50 miles) • Thermosphere ( above 50 miles to about 300 mi) • Exosphere – (above 300 miles to outer space)

7. Hydrosphere • Liquid water • Ice • Polar • Permafrost • Water vapor • Lithosphere • Crust • Upper mantle • Biosphere • The biotic portion • The abiotic portion that biota interacts with • The goal of ecology is to understand the interactions

8. What sustains life on Earth? • One-way flow of high-quality (low-entropy) energy from the sun • Cycling of matter through the biosphere • Gravity – allows planet to hold on to its atmosphere and causes downward movement of matter • How does the sun help sustain life on Earth? • Lights and warms the planet • Supports photosynthesis • Powers the cycling of matter • Drives the climate and weather systems that distributes heat and fresh water over the Earth’s surface. • Sun is composed of 72% H and 28% He • Thermonuclear reactor that fuses H to form He

9. Sunlight reaches the Earth in 8 minutes • Most that reaches troposphere is visible light • Infrared radiation (heat) • Small amount of UV not absorbed by ozone • 34% of solar energy is reflected back into space by • Clouds • Chemicals • Dust • Earth’s land masses and seas • Remaining 66% of solar energy • Warms troposphere and land • Evaporates water and cycles it • Generates wind • 0.023% is captured by green plants, algae, bacteria to fuel photosynthesis • Most unreflected solar radiation is degraded into heat as it interacts with the Earth • Greenhouse gases (H2O vapor, CO2, CH4, N2O, O3) reduce the flow of heat back to space • Natural greenhouse effects occur also

10. Ecosystem Concepts and Components • What are biomes and aquatic life systems? • The biosphere is divided into biomes characterized by: • Distinct climate • Specific life forms • Specific soils • Climate – long term 30 year pattern of weather • Aquatic life zones are equivalent to biomes • Freshwater life zones • Lakes and streams • Ocean or marine life zones • Estuaries • Coastlines • Coral reefs • abyss

11. Do ecosystems have distinct boundaries? • Natural ecosystems rarely have distinct boundaries • Ecotones are areas where two ecosystems overlap • Marsh is found between a wet and a dry ecosystem. • What are the major components of ecosystems? • Abioticcomponents • Water • Air • Nutrients • Sun • Biotic components • Plants • Animals • microbes

12. What are the major nonliving components of ecosystems? • Amount of sunlight • Temperature • Range of tolerance – physical and chemical environment • Individuals may have a slightly different tolerance range due to genetic makeup • Optimum level or range – where most survive • Wind • Latitude • Fire frequency • For aquatic life zones • Light penetration • Dissolved oxygen (DO) and amount of P and N • Suspended solids (turbidity)

13. Law of Tolerance – existence, abundance and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within tolerated ranges • Minimum and maximum limits for conditions are called tolerance limits • Most organisms are least tolerant during juvenile or reproductive stages • Limiting factor – the one more important factor that regulates population growth • Limiting factor principle – too much or too little of any abiotic factor can limit growth, even if all other factors remain the same

15. Limiting Factors • On land, precipitation often is the limiting factor along with soil nutrients • Too much of an abiotic factor can also be a limiting factor • Too much water or too much fertilizer can kill plants • Limiting factor for a particular population can change • Important limiting factors in aquatic life zones • Temperature • Sunlight • DO • Nutrient availability • salinity

16. What are the major living components of ecosystems? • Metabolism – capture and transform matter and energy from the environment to supply needs for growth, survival, reproduction • Organisms in ecosystems • Producers – autotrophs • On land – green plants • In freshwater and near shorelines – algae, plants • In open ocean – phytoplankton • Producers capture sunlight to make carbohydrates • Photosynthesis • Chemosynthesis

17. Consumers – heterotrophs • Primary consumers – herbivores • Secondary consumers – carnivores • Tertiary consumers – carnivores • Omnivores (pigs, humans, rats, foxes, bears, cockroaches) • Scavengers –vultures, flies, hyenas, some sharks, ants) • Detritivores • Detritus feeders – feed on detritus (dead organic matter such as cast off parts of animals) • Decomposers – bacteria and fungi (biodegrade to their nutrients and leave simpler compounds for producers to use)

19. Both producers and consumers use chemical energy stored in glucose and others to fuel life processes • Aerobic respiration • Anaerobic respiration • Survival depends on the one-way flow of energy and cycling of matter through its body • Ecosystems survives through combination of matter recycling and one-way flow of energy • Decomposers complete the cycle – very necessary