Ecosystem Function and Structure The Earths LifeSupport Systems

Ecosystem Function and Structure

The Earth’s Life-Support Systems • The Earth is made up of 4 different spherical layers 1. Atmosphere – thin envelope or membrane of gases (mostly Nitrogen and Oxygen) – Troposphere – inner layer of the atmosphere that extends up to about 17 km (weather) – Stratosphere – second layer of the atmosphere that extends 17 -48 km (ozone layer)

The Earth’s Life-Support Systems 2. Hydrosphere – consists of (1) liquid water, (2) ice, and (3) water vapor 3. Biosphere – portion of earth in which living organisms interact with one another and their abiotic environment. 4. Lithosphere – outer shell of the earth, composed of the crust and upper mantle

What sustains life on Earth? • The one-way flow of high-quality energy from the sun through materials and living things in their feeding interactions, into the environment as low-quality energy, and eventually back into space as heat. • The cycling of matter through parts of the biosphere. (Earth is almost a closed system) • Gravity which allows the planet to hold on to its atmosphere and causes the downward movement of chemicals in the matter cycles.

The Solar Engine • Incoming Solar Radiation: – Temperature regulation – Light and photosynthesis – Drives matter cycles and climate – Incoming energy is in the form of • visible light, heat, and UV radiation.

Photosynthesis • Autotrophs (primary producers) = organisms such as green plants, algae and cyanobacteria produce their own food from the sun’s energy • Photosynthesis = the process of turning light energy from the sun into chemical energy – Carbon dioxide + water + sun’s energy is converted into sugars and high-quality energy

Photosynthesis produces food • Chloroplasts = organelles where photosynthesis occurs – Contain chlorophyll = a light-absorbing pigment – Light reaction = splits water by using solar energy – Calvin cycle = links carbon atoms from carbon dioxide into sugar (glucose) 6 CO 2 + 6 H 20 + the sun’s energy C 6 H 12 O 6 + 6 O 2

Cellular respiration releases chemical energy • Organisms use chemical energy from photosynthesis • Oxygen is used to convert glucose into water + carbon dioxide + energy • Heterotrophs = organisms that gain energy by feeding on others C 6 H 12 O 6 + 6 O 2 – Animals, fungi, microbes 6 CO 2 + 6 H 2 O + energy

Geothermal energy powers Earth’s systems • Hydrothermal vents = host entire communities that thrive in high temperature and pressure – Lack of sun prevents photosynthesis – Chemosynthesis = uses energy in hydrogen sulfide to produce sugar 6 CO 2 + 6 H 20 + 3 H 2 S C 6 H 12 O 6 + 3 H 2 SO 4

Major Ecosystem Components • Biotic (plants, animals, microorganisms, etc. ) • Abiotic (water, air, nutrients, temperature, sunlight, etc. ) • Most organisms have a range of tolerance for abiotic components • This range contributes to an organisms’ limiting factors, a single (or sometime multiple) factor that limits the number of organisms that an ecosystem can support OR limits the range in which an organisms can survive. – Ex. Food or Temperature

Natural Resources • Natural capital – goods and services provided by the environment • Natural income – amount of natural capital that is renewed annually • 3 types of natural resources: – Renewable – biotic resources that will renew themselves within a human lifetime – Replinishable – abiotic resources that depend on the sun to renew or replace them selves within a human lifetime – Nonrenewable – resource that is only available to be used once.

Biosphere Ecosystems Communities Populations Organisms

NICHE = all of the ways that the organism interacts with everything else in the ecosystem-the role or job of a species in an ecosystem. HABITAT = place where an organism or population of organisms live.

Biotic Components of Ecosystems • Producers (autotrophs) – create their own food through photosynthesis or chemosynthesis. • Herbivores – primary consumers, feeding directly on producers • Carnivores – feed on other consumers • Omnivores – feed on producers and consumers

Biotic Components of Ecosystems • Detritivores or detritus feeders – feed on parts of dead organisms and waste of organisms. – Decomposers – recycle organic matter in ecosystems by breaking down detritus to get nutrients and releasing simpler inorganic compounds into the soil and water. – Scavengers – feed on dead animals that they did not kill themselves.

Food Webs and Energy Flow in Ecosystems • Food chain – sequence of organisms, of which each is source of food for the next. • Tropic level – the feeding level of an organisms, depending on whether it is a producer or consumer • Energy flow is represented in terms of biomass – the dry weight of all organic matter contained in organisms • With each transfer of chemical energy between trophic levels, usable energy is degraded and lost as heat (2 nd law of thermodynamics) • Approximately 90% of usable energy is lost between tropic levels, resulting in a pyramid of energy flow

FOOD CHAIN = used to show matter & energy move through an ecosystem

FOOD WEB = shows all the possible food chains in an ecosystem

Each organism in food chain represents a “feeding” or TROPHIC LEVEL 3 rd Trophic Level 2 o or 3 o consumer 2 nd Trophic Level 1 o or 2 o consumer 1 st Trophic Level producers decomposers

Food Webs and Energy Flow in Ecosystems • How can energy flow pyramids demonstrate how we can support more people? • Because of the energy losses attributed to successive steps in the food chain, it explains why (1) there are few top carnivores, (2) top carnivores are severely affected when there are disruptions in the ecosystem, and (3) top carnivores are so susceptible to extinction.

Energy Flow in Ecosystems • Pyramids of Biomass represent the storage of biomass in various trophic levels in the ecosystem. (Dry weight of organisms by trophic level)

Primary Productivity of Ecosystems • Gross Primary Productivity (GPP) - The total gain in energy or biomass per unit area per unit time fixed by photosynthesis in green plants or the rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. – It is greatest in shallow waters near continents, along coral reefs, and where ocean upwelling bring nutrients (N and Ph) to the surface.

Primary Productivity of Ecosystems • Net Primary Productivity (NPP) - The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). This is potentially available to consumers in an ecosystem – or what is left after the organisms uses energy that is produced for its own metabolic processes. • NPP = GPP – R • where R = respiratory loss

Secondary Productivity of Ecosystems Gross Secondary Productivity (GSP) - The total gain by consumers in energy or biomass per unit area per unit time through absorption. • GSP = food eaten – fecal loss • Net Secondary Productivity (NSP) - The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses (R). • NSP = GSP – R • where R = respiratory loss