Structure of an Ecosystem

Ecosystems a community of interdependent organisms and the physical environment they inhabit.

Ecology the study of the inter- relationships of organisms with each other and the environment..

Ecosystem Components 2 parts –Abiotic – nonliving components (water, air, nutrients, solar energy) –Biotic – living components (plants, animals, microorganisms) Biota

Terrestrial Ecosystems Aquatic Life Zones Sunlight Temperature Precipitation Wind Latitude (distance from equator) Altitude (distance above sea level) Fire frequency Soil Light penetration Water currents Dissolved nutrient concentrations (especially N and P) Suspended solids Salinity Significant abiotic factors

What abiotic factors effect this Aquatic food chain?

The abiotic influence Species thrive in different physical conditions Population has a range of tolerance for each factor Optimum level best for most individuals Highly tolerant species live in a variety of habitats with widely different conditions

Population Size LowHigh Temperature Zone of intolerance Zone of physiological stress Optimum range Zone of physiological stress Zone of intolerance No organisms Few organisms Lower limit of tolerance Abundance of organisms Few organisms No organisms Upper limit of tolerance The Law of Tolerance: The 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 the range tolerated by that species

Abiotic factors may be Limiting Factors Limiting factor – one factor that regulates population growth more than other factors Too much or too little of an abiotic factor may limit growth of a population Determines K, carrying capacity of an area Examples –Temperature, sunlight, dissolved oxygen (DO), nutrient availability

Terminology and Roles of Biota Producers (Autotrophs) – Through photosynthesis convert radiant to chemical energy (energy transformation) Consumers (Heterotrophs) – Must consume other organisms to meet their energy needs –Herbivores, Carnivores, Omnivores, Scavengers, Detritivores Decomposers – Break down organisms into simple organic molecules (recycling materials)

Tropic Levels The terms producer, primary consumer, secondary consumer and tertiary consumer refer to the organisms feeding level in a food chain or web – this is called its TROPHIC LEVEL.

Tropic Levels TROPHIC LEVEL – the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.

Food chains Food chain - Sequence of organisms each of which is the source of food for the next

Food chains Feeding levels in the chain (Trophic levels) –First trophic level = producer –Second trophic level = consumer, herbivore –Third trophic level = consumer, carnivore –Highest trophic level = top carnivore –Arrows indicate direction of energy flow!!! –Decomposers are not included in food chains and webs

Producers Transform energy into a usable form Starting form may be light energy or inorganic chemicals Turned into organic chemical energy This is the form that is used at other trophic levels

Food Webs Ecosystem is an energy machine and a matter processor 1.Autotrophs: make their own food (plants algae & photosynthetic prokaryotes) 2.Heterotrophs: directly or indirectly depend on photosynthetic output of primary producers

Photoautotrophs

Consumers Heterotrophs: get energy from organic matter consumed Primary, Secondary & Tertiary consumers Herbivores  primary consumers, eat plant material e.g. – termites, deer Carnivores  other consumer levels, eat animal material e.g. eagles, wolves Omnivores  consumers eating both e.g. bears

Figure 53.0 Lion with kill in a grassland community

Decomposition Decomposers obtain energy by breaking down glucose in the absence of oxygen Anaerobic respiration or fermentation End products = methane, ethyl alcohol, acetic acid, hydrogen sulfide Matter recycling  inorganic nutrients returned to producers

Mushroom Wood reduced to powder Long-horned beetle holes Bark beetle engraving Carpenter ant galleries Termite and carpenter ant work Dry rot fungus Detritus feedersDecomposers Time progression Powder broken down by decomposers into plant nutrients in soil Decomposition Process

Consumers or Decomposers Detritivores = get their energy from detritus, nonliving organic material  remains of dead organisms feces, fallen leaves, wood May link producers to consumers –Dung beetles, earth worms Saprotrophs = feed on dead organic material by secreting digestive enzymes into it and absorbing the digested products Producers can reassimilate these raw materials –Fungi (mold, mushrooms), bacteria

Figure Examples of terrestrial and marine food chains

Local examples Trophic LevelAquatic systemTerrestrial habitat Producer Primary Consumer Seconday Consumer Tertiary Consumer Quarternary Consumer 6 th trophic level

Food chains For complexity a real ecosystem needs FOOD WEB which shows that individuals may exist at multiple trophic levels in a system (omnivores)

Figure An antarctic marine food web: Identify the trophic levels

Food Webs Food webs are limited by the energy flowing through them and the matter recycling within them