Ecosystems: What Are They and How Do They Work

Ecosystems: What Are They and How Do They Work Chapter 3 (Miller and Spoolman, 2010)

Hierarchy of Life

Living Organisms in Ecosystem Producers or autotrophs- makes their own food from compound obtained from environment. • Ex: plant gets energy or food from sun

Living Organisms in Ecosystem Photosynthesis- ability of producer to convert sunlight, abiotic nutrients to sugars and other complex organic compounds • Chlorophyll- traps solar energy and converts into chemical energy

Producer transmit 1-5% of absorbed energy into chemical energy, which is stored in complex carbohydrates, lipids, proteins and nucleic acid in plant tissue

Chemosynthesis- • Bacteria can convert simple compounds from their environment into more complex nutrient compound without sunlight • Ex: becomes consumed by tubeworms, clams, crabs • Bacteria can survive in great amount of heat

Consumers or Heterotrophs • Obtain energy and nutrients by feeding on other organisms or their remains

Consumers • Herbivores (plant-eaters) or primary consumers • Feed directly on producers • Deer, goats, rabbits http://www.holidays.net/easter/bunny1.htm

Consumers • Carnivores (meat eater) or secondary consumers • Feed only on primary consumer • Lion, Tiger

Consumers • Tertiary (higher-level) consumer • Feed only on other carnivores • Wolf

Consumers • Omnivores- consumers that eat both plants and animals • Ex: pigs, humans, bears

Consumers • Scavengers- feed on dead organisms • Vultures, flies, crows, shark

Consumers • Detritivores- live off detritus • Detritus parts of dead organisms and wastes of living organisms. • Detritus feeders- extract nutrients from partly decomposed organic matter plant debris, and animal dung. • EX. Earthworms, millipedes, woodlice, dung beetles

Consumers • Saprotrophs- Fungi and bacteria break down and recycle organic materials from organisms’ wastes and from dead organisms • Food sources for worms and insects • Biodegradable - can be broken down by decomposers

Distinguish between consumers, detritivores and saprotrophs • Detritivores - organisms that feed on the detritus (thus detritivore)and decomposing organic material of living organisms (eg. dung beetle). • Saprotrophsorganisms that feed on dead organisms and products of living organisms. They secrete enzymes on these materials that cause decomposition, and then they absorb the resulting simple compounds into their bodies. So they do not ingest whole food, but rather, they absorb decomposed and digested food. Examples are bacteria and fungi.

Respiration • Aerobic Respiration • Uses oxygen to convert organic nutrients back into carbon dioxide and water • Glucose + oxygen  Carbon dioxide + water + energy • Anaerobic Respiration or Fermentation • Breakdown of glucose in absence of oxygen

Food Chain • Food Chain-Series of organisms in which each eats or decomposes the preceding one • Decomposers complete the cycle of matter by breaking down organic waste, dead animal. Plant litter and garbage. • Whether dead or alive organisms are potential (standard) sources of food for other organisms.

Second Law of Energy • Organisms need high quality chemical energy to move, grow and reproduce, and this energy is converted into low-quality heat that flows into environment • Trophic levels or feeding levels- Producer is a first trophic level, primary consumer is second trophic level, secondary consumer is third. • Decomposers process detritus from all trophic levels.

Food Web • Complex network of interconnected food chains • Food web and chains • One-way flow of energy • Cycling of nutrients through ecosystem

Food Webs • Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (100,000 Units of Energy)

Food Webs • Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (1,000 Units of Energy)

Food Webs • Grazing Food Webs • Energy and nutrients move from plants to herbivores • Then through an array of carnivores • Eventually to decomposers (100 Units of Energy)

Food Webs • Detrital Food Webs • Organic waste material or detritus is the major food source • Energy flows mainly from producers (plants) to decomposers and detritivores.

Pyramid of Energy Flow • More steps or trophic levels in food chain or web, greater loss of usable energy as energy flows through trophic levels • More trophic levels the Chains or Webs have more energy is consumed after each one. That’s why food chains and webs rarely have more than 4 steps

Pyramid of Energy Flow • Loss of usable energy as energy flows through trophic levels of food chains and webs • Rarely have more than 4 steps

Biomass • Dry weight of all organic matter contained in organisms. • Biomass is measured in dry weight • Water is not source of energy or nutrient • Biomass of first trophic levels is dry mass of all producers • Useable energy transferred as biomass varies from 5%-20% (10% standard)

Pyramid of Biomass Storage of biomass at various trophic levels of ecosystem

Pyramid of Numbers Number of organisms at each trophic level

http://www.nicksnowden.net/Module_3_pages/ecosystems_energy_flows.htmhttp://www.nicksnowden.net/Module_3_pages/ecosystems_energy_flows.htm

Gross Primary Productivity (GPP) Rate in which producers convert solar energy into chemical energy (biomass) in a given amount of time

Net Primary Productivity (NPP) • Rate in which energy for use by consumers is stored in new biomass of plants • Measured in kilocalories per square meter per year or grams in biomass • NPP is the limit determining the planet’s carrying capacity for all species. • 59% of NPP occurs in land / 41% occurs in ocean

Ecological Efficiency • Percentage of energy transferred from one trophic level to another. • 10% ecological efficiency • 1,000,000 units of energy from sun • 10,000 units available for green plants (photosynthesis) • 1000 units for herbivores • 100 units for primary carnivores • 10 units for secondary carnivores

Studying Ecosystems • FIELD RESEARCH • Going into nature and observing/measuring the structure of ecosystems • Majority of what we know now comes from this type • Disadvantage is that it is expensive, time-consuming, and difficult to carry out experiments due to many variables • LABORATORY RESEARCH • Set up, observation, and measurement of model ecosystems under laboratory conditions • Conditions can easily be controlled and are quick and cheap • Disadvantage is that it is never certain whether or not result in a laboratory will be the same as a result in a complex, natural ecosystem • SYSTEMS ANALYSIS • Simulation of ecosystem rather than study real ecosystem • Helps understand large and very complicated systems

Ecosystem Importance • Ecosystem services are the natural services or earth capital that support life on the earth • Essential to the quality of human life and to the functioning of the world’s economies

Ecosystem Importance • Ecosystem services include: • Controlling and moderating climate • Providing and renewing air, water, soil • Recycling vital nutrients through chemical cycling • Providing renewable and nonrenewable energy sources and nonrenewable minerals • Furnishing people with food, fiber, medicines, timber, and paper

Ecosystem Importance • Ecosystem services include • Pollinating crops and other plant species • Absorbing, diluting, and detoxifying many pollutants and toxic chemicals • Helping control populations of pests and disease organisms • Slowing erosion and preventing flooding • Providing biodiversity of genes and species

Why Is Biodiversity So Important? • Food, wood, fibers, energy, raw materials, industrial chemicals, medicines, … • Provides for billions of dollars in the global economy • Provides recycling, purification, and natural pest control • Represents the millions of years of adaptation, and is raw material for future adaptations

Ecosystems: What Are They and How Do They Work