Ecology

Ecology

• Organisms – all living things

• Environment – everything that surrounds or affects an organism, living and nonliving, like light, heat, soil, water and air

• Ecology – the study of living things and their relationship to their environment

Requirements for Life

• Liquid water• Carbon and other chemical elements• Gravity to retain our atmosphere• Continuous and unwavering energy supply

Other important factor• Magnetic field (to protect from solar particles)

Ecosystem

• A group of organisms

interacting with each other and

their surroundings

• Distinguished by different climate, soil, vegetation and animals

• Maintains a balance (that can be fragile)

• The largest terrestrial ecosystems are biomes

• Recognized by their similar characteristics– Examples: Deserts, temperate forests, tropical

rain forests, oceans, mountains, grasslands, rivers, and lakes

Community

• A group of living things within an ecosystem

• Relatively small changes can change or upset the balance of the community and begin a process of change

• Species – a group of animals that are able to breed freely and produce fertile offspring (further definition maybe necessary in some cases - DNA)

• Population – members of the same species sharing a habitat

• Habitat – an environment with certain characteristics

• Niche – the effects an organism has on its surroundings and how the surroundings affect the organism

• Ecological succession – orderly progression of changes producing a stable or climax community e.g. weeds, grass, shrub, forest

Food Chain

• Each organism is food for the next in line

• All energy originates from the Sun

• Producers or autotrophs convert this energy to organic molecules

• Consumers or heterotrophs - eat other organisms

• Primary consumers eat plants

• Secondary and tertiary eat the herbivores and carnivores respectively

• Omnivores - eat both plants and animals

• Decomposers - eat dead organic material

Food Web

• Because few organisms eat one kind of food

• Bioaccumulation - the storage of chemicals within an individual organism at higher levels than those found in the environment

• Biomagnification – when chemicals accumulate at increasingly higher concentrations at successive levels of the food chain

Energy Flow

• Trophic level – level of energy consumption within the food web

• T1 – producers

• T2 – primary consumers

• T3 – secondary consumers

Energy (an aside)

• The ability or capacity to do work

• Heat, electrical, mechanical or chemical

• Potential energy is stored and available to do work

• Kinetic energy is called the energy of motion

Laws of Thermodynamics

• The study of energy, its functions and transformations

• Energy flow from one trophic level to the next results in a significant loss of usable energy

• Most energy is used by an organism for movement and digestion etc.

• Just 10 – 15% is stored for use by the next predator

Ecological Pyramids (Fig. 4-5)

• Numbers – how many organisms occupy each level• Biomass• Energy

• At each trophic level there is a 90% reduction in biomass and energy

The Carbon Cycle

• Biochemical cycle – ties living organisms to the physical environment

• Carbon is contained in over 80% of all known compounds

• Photosynthesis converts CO2 and H2O to make glucose C6H12O6

Carbon Cycle II

• Long term carbon cycle involves longer term geologic processes; with time frames in the thousands and millions of years

Long term Carbon Cycle

Carbon Cycle III

• Shorter biological carbon cycle; involves processes whose time frames are in 10’s of years to thousands of years

Short term Carbon Cycle

Carbon Cycle IV

• Relationship between shorter & longer term cycles is complex

• Involves several feed back loops between the two cycles

Carbon Cycle V

Human impact on carbon cycle

Nitrogen Cycle

• The circulation of nitrogen through plants and animals and back to the atmosphere

• 78% of the atmosphere by volume

• Essential for the manufacture of proteins and other molecules vital for growth and reproduction

• Nitrogen from the atmosphere is removed by nitrogen fixation carried on by some bacteria, algae and lichens and turned into ammonia, nitrates and nitrites

• These substances can be taken up by plant roots and used to manufacture proteins

• Nitrogen compounds return to the soil as animal waste and through the decay of dead plants and animals

• Denitrifying bacteria return the nitrogen to the atmosphere by breaking down nitrites

The Hydrologic Cycle

• Describes water’s circulation through the environment

• Only 2% of water taken in by plant roots is used in photosynthesis, the rest is released to the atmosphere in a process called transpiration

Ecological Concerns

• Acid deposition (acid rain) & mercury

• Ozone depletion

• Species loss

• Global warming

• Population (human) increase

Ecological Concerns II

• Soil erosion

• Food and water demands

• Deforestation

• Energy use

• Dwindling mineral resources

• Rain with a pH of less than 5.6 is considered acid rain

• Acid precipitation problems are noticed first in aquatic systems because soils have a much greater buffering capacity

• Acid deposition can leach nutrients from the soil, hamper microorganisms that nourish plants and release toxic metals

Ozone Depletion

• CFC’s and halons are breaking down the ozone molecules in the upper atmosphere

• Increased UV rays cause more cases of skin cancer, decreased crop yields, reduces the population of certain fish larvae, and reduces the life of outdoor paints and plastics

Global Warming

Change in global climate due to greater retention of planetary surface heat; due to:

• Burning fossil fuels (coal, oil, gas) & other combustible fuels (creating green house gases like CO2, methane, etc.)

• Clearing the rainforest, and agricultural practices

• Environmental feedbacks, methane & CO2

Global Heat Balance for Surface of the Planet

Energy balance:

• Incoming radiation (visible & UV)

• Heat mixing & distribution

• Outgoing surface radiation (IR)

Global temperature change

Tem

pera

ture

(o C

elsi

us)

The gray represents uncertainty

• Global temperatures have risen over the last century and evidence indicates they continue to rise

• Global warming results in climate change, that alter global weather patterns and regional climates

• Sea level has risen nearly 8” in the last century and further rises will inundate coastal wetlands, erode recreational beaches and increase salinity of estuaries and groundwater

• Impacts also include the pH of the worlds oceans having impacts on oceanic life (e.g. coral reefs)

Temperature variation over the last 160 thousand years as recorded in Greenland ice core data

Greenland Ice Cores• Oxygen isotopes in the ice tell

us the atmospheric temperature at each time

• Trapped air in the ice tells us the composition of the atmosphere at each time Air bubbles

Species Loss

• Biologic diversity – variety and variability among living organisms and ecological complexes

• Ecosystem diversity

• Species diversity

• Genetic diversity

• Estimates of total species are approaching 30 million

• We are losing 17,500 per year

• Many are untapped resources for agricultural, industrial and medicinal development

Wetlands and Rainforests

• 55% of wetlands in the US have been converted for industrial, residential and agricultural purposes

• Although rainforests cover only 7% of the earth’s surface they harbor over 50% of the world’s plant and animal species

Benefits of Sustaining Wetlands

• Species diversity

• Flood control

• Filtration

Benefits of the Rainforests

• Absorb rainfall and release moisture into the atmosphere affecting the world’s weather patterns

• Absorbs a large percentage of the world’s CO2 emissions

• Controls soil erosion and landslides• Creates essential oxygen• Moderates the effects of floods and droughts

Environmental Protection (NEPA)

• National Environmental Policy Act (1970)

• States our intent to achieve productive and enjoyable harmony between the activities of humans and the environment

NEPA II

• Implemented by the EPA

• No enforcement agency, lawsuits from outside the government

• Established the Council of Environmental Quality – CEQ overseeing federal environmental issues

Environmental Assessment (under NEPA)

• Study of any governmental actions

• May result in the filing of a Finding of No Significant Impact – FONSI

• Or an Environmental Impact Statement – EIS, must be prepared for any project if government funding or regulations are involved

NEPA III

• The EPA is a major reviewer of EIS’s

• The input and disclosure process built into NEPA give the public an opportunity to participate in the decision-making process

• Many states have statutes that parallel NEPA (New York State, SEQR – State Environmental Quality Review Act)