BRINGING IT ALL BACK TOGETHER

We’ve discussed how Earth is a closed system except for the input of SOLAR ENERGY.

So how does everything we’ve been talking about all link together?

WHAT SUPPORTS LIFE ON EARTH?• The cycling of MATTER• nutrients are constantly being recycled in order for life to

continue. (it cannot be created)

• GRAVITY• aids in matter cycling and keeps the atmosphere in place.

• The SUN: • provides the one way energy flow for life on Earth. It lights

and warms the planet. It supports photosynthesis. It powers the matter cycles. It drives climate and weather systems.

THE EARTH RECEIVES ONLY 1 BILLIONTH OF THE SUN’S ENERGY

• Most of it reaches earth as visible light, infrared radiation (heat), and UV radiation.

• This energy warms the atmosphere and land, evaporates water and cycles it through the biosphere, and generates winds

• A small fraction is captured by photosynthesizers.

• Greenhouse gases capture heat in the “natural greenhouse effect”

BRIEF REVIEW• Ecology:

• The study of how organisms interact with one another and with their nonliving environment.

• Population: • group of interacting individuals of the same species that occupy

a specific area at the same time.

• There is genetic diversity amongst the individuals in the population (genetic diversity)

• Populations can change in size, age distribution, density, and genetic composition

• Community• All of the different interacting populations

STILL REVIEWING

• Gross (GPP)

• the rate at which an ecosystem’s producers convert solar energy into chemical energy. (The rate at which plants photosynthesize)

• Net (NPP):

• GPP- energy needed for respiration by photosynthesizer.

• It is the energy available to be passed on to the next trophic level

• Highest NPP per m2: estuaries, swamps +marshes, tropical rain forests

• Lowest NPP per m2: desert, open ocean, tundra

HOW DOES ENERGY MOVE THROUGH A SYSTEM?

HOW DOES ENERGY FLOW THROUGH A SYSTEM?

• Concept: As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each successive feeding level decreases.• Rule of 10%: About 10% of energy is available (90%) “lost” at each

transfer

PYRAMID OF ENERGY FLOWDepiction of energy transfer through each tropic level

PYRAMID OF NUMBERSGives a visualization of the total number of organisms at each level

PYRAMID OF BIOMASSDry weight of organisms at each tropic level

ECOLOGICAL SUCCESSION• Gradual change is species composition in a given area over

time due to changing environmental factors

• Was once believed to be a predictable process but now views have changed and is believed to be a complex process

• As succession progresses

• biodiversity increases

• community interactions increase

• enhancement of energy flow

• increased nutrient cycling

• New species hinder the growth of older species.

• Large trees block sunlight and destroy shade intolerant plants

• Pine trees drop needles which then changes the acidity of the soil

• Older plant species set the stage for new plant species to be supported in area.

• Lichen begin to break down rocks to start creating soil for plants with roots.

• Annuals begin to die and add nutrients to soil to begin making thicker soil

SUCCESSION DEMONSTRATES FACILITATION AND INHIBITION…

Facilitation Inhibition

… AND TOLERANCE

• Seen in late succession

• All plants that succeed and survive for long periods because they are no longer in competition with others.

PRIMARY SUCCESSION

• Occurs when there is no soil or no sediment

• Very slow process because need to create soil before able to support variety of life

• Examples

• Parking lots

• Area covered in lava

• Bare rocks

SECONDARY SUCCESSION

• Occurs in an area that has been disturbed/destroyed but soil / sediment remain intact.

• More rapid of a process than primary success and more common.

• Occurs

• After forest fires

• Floods

• deforestation

• The ability to recover after an environmental disturbance via secondary succession.

• Grasslands have low richness, but high abundance. They have low inertia, but majority of plant mass is underground so they can recover quickly after a major disturbance

• Ability for ecosystems to withstand /resist environmental change or disturbance

• Woodlands have high inertia.

• Tropical rainforests have high species richness and high inertia. But if mass deforestation occurred then it is highly unlikely it will bounce back.

SUCCESSION IS RELATED TO SUSTAINABILITY

Inertia / persistence Resilience