ecosystems and energy - napa valley college study of interactions among and between organisms in...

Ecosystems and Energy3

© 2015 John Wiley & Sons, Inc. All rights reserved.

Overview of Chapter 3

◻ What is Ecology?◻ The Energy of Life

⬜ Laws of Thermodynamics⬜ Photosynthesis and Cellular Respiration

◻ Flow of Energy Through Ecosystems⬜ Producers, Consumers and Decomposers⬜ Path of Energy Flow: Who Eats Whom⬜ Ecological Pyramids⬜ Ecosystem Productivity


Chesapeake Bay salt marshes

◻ An estuary – semi-enclosed body of water where freshwater drains into ocean⬜ Tidal – gradual changed from fresh to salt water

◻ Cordgrass dominates – brackish◻ Home to insects and birds,

nursery for fish◻ Very important buffer for

coasts against storms


Ecology

◻ Ecology⬜ “logy” study of, “eco” house – study of one’s house⬜ The study of interactions among and between

organisms in their abiotic environment◻ Biotic - living environment

⬜ Includes all organisms◻ Abiotic - non living or physical environment

⬜ Includes living space, sunlight, soil, precipitation, etc.


Ecology

◻ Organisms interact with biotic components, but also effect many physical and chemical processes

◻ Physical – walking on soil

◻ Chemical – CO2, O2, wastes


Ecology

◻ Ecologists are interested in the levels of life above that of organism


Ecology Definitions

◻ Species - A group of similar organisms whose members freely interbreed to produce fertile offspring

◻ Population - A group of organisms of the same species that live in the same area at the same time

◻ Community - All the populations of different species that live and interact in the same area at the same time

◻ Ecosystem - A community and its physical (abiotic) environment

◻ Landscape - Several interacting ecosystems (ex: bear hunting for salmon in a river, living in adjacent forest)


Part of Earth that contains living organisms

Ecology

Community and physical environment

Individuals

Group of same species

All populations of species in an area


Ecology

◻ Coral Reef communities – similar to rainforests for number of species and productivity

◻ Threatened with changing climate◻ How can communities

be protected from warming waters?

◻ What could loss mean?


Ecology◻ Biosphere contains earth’s communities,

ecosystems and landscapes, and includes:▪ Atmosphere-

gaseous envelope surrounding earth

▪ Hydrosphere- earth’s supply of water

▪ Lithosphere- soil and rock of the earth’s crust


Ecology

Lithosphere

Hydrosphere

Atmosphere


Energy of Life

◻ The ability or capacity to do work◻ Chemical, Thermal, Mechanical, Nuclear,

Electrical, and Radiant/Solar (below)


◻ Solar radiation is the primary source of energy on planet

Energy of Life

Plants turn solar radiation into food


Energy of Life

◻ Energy exists as:⬜ Potential energy

(stored energy) ⬜ Kinetic energy

(energy of motion)

◻ Potential energy is converted to kinetic energy as arrow is released from bow


Thermodynamics

◻ Study of energy and its transformations◻ System- the object being studied

▪ Closed System- Does not exchange energy with surroundings (rare in nature)

▪ Open System- exchanges energy with surroundings


Laws of Thermodynamics

◻ First Law of Thermodynamics⬜ Energy cannot be created or destroyed; it can

change from one form to another

▪ Energy is absorbed by water and plate, but not lost


Laws of Thermodynamics

◻ Second Law of Thermodynamics⬜ When energy is converted form one form to

another, some of it is degraded to heat⬜ Heat is highly entropic (disorganized)

▪ Water in sunlight will get warmer

▪ Engine converts chemical energy of gasoline into mechanical energy inefficiently


Photosynthesis

◻ Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules

6 CO2 + 12 H2O + radiant energy

C6H12O6 + 6 H2O + 6 O2

Chlorophyll in plants


Cellular Respiration

◻ The process where the chemical energy captured in photosynthesis is released within cells of plants and animals

◻ This energy is then used for biological work

C6H12O6 + 6 O2 + 6 H2O

6 CO2 + 12 H2O + energy


Photosynthesis and Cellular Respiration


Life without Sun

◻ 1970s – discovered hydrothermal vents in deep ocean (200oC or 392oF)

◻ Rich ecosystem supported without light◻ Bacteria perform

chemosynthesis⬜ Similar to

photosynthesis, but use chemical (H2S) not sunlight


Energy Flow Through Ecosystems

◻ Passage of energy through an ecosystem


Food Chains- The Path of Energy Flow

◻ Energy from food passes from one organism to another based on their Trophic Level⬜ Definition: An organism’s position in a food chain,

which is determined by its feeding relationships◻ First Trophic Level: Producers◻ Second Trophic Level: Primary Consumers◻ Third Trophic Level: Secondary Consumers◻ Decomposers are present at all trophic levels


Food chains

◻ Autotrophs = Producers⬜ Auto “self” and tropho “nourishment”⬜ Produce own food from inorganic material⬜ Ex: plants via photosynthesis and hydrothermal

vent bacteria via chemosynthesis


Food chains

◻ Heterotrophs = Consumers⬜ heter “different” and tropho “nourishment”⬜ Uses bodies of other organisms as food

◻ Omnivores – eat both plants and animals


Food chains

◻ Consumers of detritus (detritivores)⬜ Eat dead material such as leaves, carcasses,

feces⬜ Ex: crabs, worms, millipedes, snails


Food chains

◻ Decomposers or saprotrophs⬜ sapro “rotten” and tropho “nourishment”⬜ Breakdown dead organic material⬜ Release inorganic molecules (CO2 and nutrients)

that producers can use⬜ Ex: fungus,

bacteria⬜ Involved in

all aspects of food chains


Food Web

◻ Food web visualizes feeding relationships within a community⬜ More complex

than food chain⬜ Still simplified

compared to nature


Ecological Pyramids

◻ Graphically represent the relative energy value of each trophic level⬜ Important feature - large amount of energy is lost

as heat between trophic levels◻ Three main types

⬜ Pyramid of numbers ⬜ Pyramid of biomass⬜ Pyramid of energy


Pyramid of Numbers

◻ Illustrates the number of organisms at each trophic level▪ Fewer organisms

occupy each successive level

❑ Does not indicate:▪ biomass of organisms

at each level▪ amount of energy

transferred between levels


Pyramid of Biomass

◻ Illustrates the total biomass at each successive trophic level

❑ Biomass: measure of the total amount of living material

❑ ~90% reduction in biomass through trophic levels❑ 100 to 10


Pyramid of Energy

◻ Illustrates how much energy is present at each trophic level and how much is transferred to the next level

◻ Most energy dissipates between trophic levels⬜ Lost as heat and energy

to maintain each level◻ Explains why there are

so few trophic levels


Ecosystem Productivity

◻ Gross Primary Productivity (GPP)⬜ Total amount of energy that plants capture and

assimilate in a given period of time◻ Cellular respiration (R)

⬜ Plants use some energy of GPP to maintain themselves

⬜ Plants respire too◻ Net Primary Productivity (NPP)

⬜ Productivity after respiration losses are subtracted⬜ What is available as food for other organisms


Ecosystem Productivity

◻ GPP is similar to gross pay in paycheck◻ R is similar to taxes◻ NPP is similar to take home pay

Net Primary Productivity

(plant growth per area per time)

Gross Primary Productivity (total photosynthesis per

area per time)

Plant Cellular Respiration

(per area per time)= -


Variation in NPP by Ecosystem

◻ Coral reefs are near tropical rain forests

◻ Humans consume a large amount of global NPP⬜ ~30% but we make up ~0.

5% of biomass

◻ This represents a threat to planet’s ability to support both human and non-human inhabitants


Energy and Climate Change

◻ Humans use a large portion of global NPP◻ If we use more biomass as energy rather than

fossil fuels, our use of NPP may increase⬜ Corn as fuel, wood for heat⬜ This removes arable land from food production

use.◻ How can we balance our needs with other

organisms?


ENVIRONEWS

◻ Use of satellite imagery improves biomass estimates of forests⬜ Help protect tropic forests in developing countries⬜ Developed countries pay to keep forests intact

◻ Need to ground truth satellite models with monitoring data from forest

Ecosystems and the Physical Environment4


Overview of Chapter 4

◻ Cycling of Materials within Ecosystems◻ Solar Radiation◻ The Atmosphere◻ The Global Ocean◻ Weather and Climate◻ Internal Planetary Processes


Hubbard Brook Experimental Forest

◻ Experimental area in White Mountains, 1950s◻ Long-term ecological data

⬜ Data on salamanders since 1970⬜ Effects of deforestation

■ Measured chemistry of stream water after forest was logged and compared to control catchment (unlogged)


Cycling of Materials

◻ Matter moves among organisms, ecosystems, and the abiotic environment

◻ Biogeochemical cycling⬜ Interactions between biological,

geological, and chemical aspects of environment

◻ Five major cycles: ⬜ Carbon, Nitrogen, Phosphorus,

Sulfur, and Water (Hydrologic)


The Carbon (C) Cycle


The Carbon (C) Cycle

◻ Global circulation of C between living and non-living environment

◻ Major processes⬜ Photosynthesis⬜ Respiration

■ Soil, in particular⬜ Combustion of fossil

fuels⬜ CO2 dissolving into

ocean


The Carbon-Silicate Cycle

◻ Over millions of years, C will interact with silicate cycle

◻ CO2 with rainwater becomes H2CO3 and will slowly weather silicate rich rocks ⬜ Calcium minerals also released

◻ Ocean organisms use Ca2+ and Si4+ to form shells

◻ When die, shells become buried and over time formed into limestone

◻ Geologic uplift or subduction


Human Affects on C Cycle

◻ Higher CO2 creates lots of feedbacks in environment⬜ > CO2 dissolved in

ocean

◻ CO2 was 0.029% of atmosphere (1700s)◻ CO2 is 0.04% (2014)◻ Expected 0.06% by 2100


The Nitrogen (N) Cycle



◻ N needed for proteins and nucleic acids (DNA)◻ Atmosphere is 78% N2, but most cannot use

this form◻ Five steps

⬜ Nitrogen fixation⬜ Nitrification⬜ Assimilation⬜ Ammonification⬜ Denitrification



1. Nitrogen fixation2. Nitrification3. Assimilation4. Ammonification5. Denitrification

N2

NH3 or NH4

+

NO2-

NO3-2.

Plants

1.3.

3.

4.

5.


The Nitrogen (N) Cycle◻ Nitrogen fixation

⬜ By bacteria (via nitrogenase enzyme), lightening, volcanoes, industrial processes

◻ Nitrification⬜ Soil bacteria convert to NO2

- then NO3-

◻ Assimilation⬜ Plants absorb NO3, NH3, or NH4

+, moves into food web◻ Ammonification

⬜ Bacteria convert organic N into NH3 or NH4+

◻ Denitrification⬜ Bacteria convert NO3

- into N2


Human Affect on N Cycle

◻ Humans have doubled N fixation⬜ Haber- Bosch process sped fertilizer production⬜ Great for efficiently growing vegetables⬜ N pollution in natural environments causes

eutrophication, over fertilization of forests◻ Combustion of fossil fuels

⬜ Produces photochemical smog⬜ Increases production of acid rain


Properties of Water

◻ Composed of 2 Hydrogen and 1 oxygen

◻ Exists as solid, liquid or gas

◻ High heat capacity◻ Polar◻ Forms hydrogen bond

between 2 water molecules⬜ H-bonds define water’s

physical properties


The Water (Hydrologic) Cycle

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