Ecological Systems

1
Ecological Systems

• Understanding and Measuring Ecosystems

2
Ecosystem Models (Ch. 3)

• Inputs energy, matter, information
• Throughputs (and storage) flows and processing
  of the inputs
• Outputs wastes, heat, behavior
• Feedback loops positive and negative
• Synergy whole is greater than the sum of parts

3
The Special Problem of Complexity

• Everything is connected to everything else.
• We can never do just one thing.
• Unexpected and unintended consequences
• But
• More complexity often means more stability.
• More stability means resistance to change.
• COMPLEXITY IS THE NATURAL END RESULT OF ECOSYSTEM
  EVOLUTION.

4
Ecosystem Structure (Ch. 3)

• Matter atoms -gt molecules -gt etc.
• Energy emr nuclear chemical, etc.
• Basic Laws of Matter and Energy
• You cant get something for nothing. (1st law)
• There is no such thing as away. (1st law)
• Everything you do is inefficient. (2nd law)

5
Ecology (Ch. 4)

• Understanding the structure of the ecosphere and
  the interactions of all its parts is the science
  of ecology.
• Ecology is the study of how organisms interact
  with each other and with their environment.
• It is a study of the living (biotic) and the
  non-living (abiotic) in all their complexity.

6
Ecosphere Structure

• The Ecosphere is organized in levels of
  increasing complexity
• Organisms
• Populations
• Communities
• Ecosystems
• Biosphere / Ecosphere / Earth

7
Population Ecology (Ch. 4 and 9)

• Population all of the members of a species
  living together in an area
• Genetic diversity of the population and selection
  by nature fuel evolution of the
  population/species.
• Habitat food, water, space, and shelter the
  environment where a population thrives
• Range the extent of area the population or
  species occupies
• Niche the role the population or species plays
  in the ecosystem

8
Population Limits

• Each population has a unique range of tolerance
  to environmental conditions.
• Populations are limited by factors such as
• Too little or too much water
• Lack of soil nutrients lack of food
• Too little or too much sun
• Improper temperatures, etc., etc.
• Competition with other species, predation, etc.
• Limiting factors are density dependent or density
  independent

9
Community Ecology (Ch. 4 and 8)

• Community all the populations of different
  species that live and interact together
• Community interactions include
• Predation
• Parasitism
• Competition
• Commensalism
• Amensalism
• Mutualism

10
Communities Change Over Time

• Ecological succession
• Primary succession
• Secondary succession
• Pioneer species establish first and build to an
  eventual climax community.
• The climax community of an area depends on
  climate (temperature and rainfall) as well as
  local factors.

11
Ecosystems and Biomes (Ch. 4 and 6)

• Ecosystem all of the communities of life and
  the physical environment in an area
• Biomes large areas of similar ecosystems that
  depend on similar climate conditions
• Biosphere or ecosphere all of the ecosystems
  and biomes of the Earth the total interaction of
  lithosphere, atmosphere, hydrosphere, and living
  things.

12
Major Terrestrial Biomes

• Tundra
• Taiga or coniferous forest or boreal forest
• Temperate deciduous forest
• Temperate grasslands
• Savanna
• Deserts (warm or cool)
• Chaparral or scrub
• Tropical forests (wet or dry/seasonal)

13
Major Aquatic Biomes (Ch. 4 and 7)

• Based on Salinity and Location
• Marine ecosystems saline
• Pelagic open sea
• Littoral coastal zone (rocky or sandy)
• Coral reefs
• Freshwater ecosystems fresh
• Lakes
• Rivers and streams
• Wetlands
• Estuarine ecosystems brackish
• Coastal wetlands
• Mangrove swamps

14
Aquatic Ecosystems

• Benthos the creatures on the bottom
• Nekton the swimming creatures
• Plankton the floating creatures or weak
  swimmers
• And the decomposers, of course
• Open ocean ecosystems (pelagic) have very little
  connection to the benthos
• Shoreline ecosystems (littoral) have a very high
  connection to the benthos and to terrestrial
  areas.

15
Setting the Foundation Soils (Ch. 4)

• The Lithosphere the solid, mineral portion of
  the Earth parent material of soil
• Soils are layered in horizons of distinct types.
• O horizon the leaf litter on top
• A horizon the topsoil minerals and humus
• B horizon the subsoil primarily inorganic
• C horizon partly weathered parent material
• R horizon the unweathered bedrock below

16
Soil Types are Characteristic of Climate

• Desert low humus high mineral fertility very
  low leaching
• Grassland v. high humus and fertility
• Coniferous forest low pH shallow profile
• Deciduous forest high litter and humus
• Tropical forest low humus and fertility high
  leaching and nutrient turnover rates

17
Soils are much more than just dirt.

• The living component of soils is critical.
• Bacteria, fungi, and other decomposers
• Micro- and macro-invertebrates abound
• Arthropods, mollusks, and various worms
• Humus the decomposed remains of life
• Plant roots hold soil and provide structure.
• Certain higher animals have important roles.

18
Building on the Foundation Energy (Ch. 3 and 4)

• Solar energy warms the planet.
• Solar energy flows through ecosystems.
• A very few ecosystems are based on other energy.
• Energy is passed from organism to organism by
  food chains and webs (trophic levels).
• Photosynthesis is the key to energy flow.
• The efficiency of photosynthesis is very low
  (lt0.1).
• The available energy is high (1000W / m2).

19
The Producer Community (Ch. 4)

• Photosynthetic plants, algae, and bacteria
• Form the basis of nearly all food chains
• Convert sunlight to stored chemical energy
• Produce oxygen as a waste product
• Also called autotrophs (autotrophic)
• Phytoplankton is an example.
• Chemosynthetic bacteria are autotrophs too.

20
Primary Productivity

• The rate at which producers make biomass
• Different ecosystems produce biomass at different
  rates.
• Net Primary Productivity (NPP)
• Total biomass converted by photosynthesis minus
  the food used to maintain life NPP
• See the table on page 72 for comparisons.
• NPP is the ultimate limit to carrying capacity.

21
The Consumer Community

• Herbivores are the primary consumers.
• Carnivores are the secondary consumers.
• Top carnivores are tertiary consumers.
• At each trophic level the energy available to the
  next level is less and less.
• As a general rule 10 is passed on
• The other 90 is lost as heat
• This is represented as an energy pyramid.

22
The Decomposer Community

• These are the ultimate recyclers of matter.
• Bacteria and fungi break down (biodegrade) dead
  bodies of all producers and consumers.
• Scavengers feed on dead plants animals.
• Detritivores feed on organic debris.
• This recycling of matter is just as important as
  the capture of energy by photosynthesis.

23
Biogeochemical (Nutrient) Cycles

• The Water Cycle see page 76.
• The Carbon Cycle see page 77.
• The Nitrogen Cycle see page 80.
• The Phosphorus Cycle see page 81.
• The Sulfur Cycle see page 83.
• Other Cycles all matter is cycled in ecosystems
  by similar means as above.

24
Matter Recycles But Energy Flows

• Food chains and food webs are complex.
• Energy flows from the sun to producers,
  consumers, and decomposers and ultimately it ends
  up as heat in the environment.
• The 2nd law of thermodynamics governs the energy
  flow. It is only 2 - 40 efficient.
• Top carnivores have the least available energy
  and are often the first to be lost.

25
Collecting Baseline Data

• Management or stewardship needs data.
• We only know half of what we need to know.
• Worldwide we know perhaps 10 of species.
• Knowing more promotes caring more.
• Knowing more promotes restoration.
• Basic research on what we have now and what we
  used to have in the past will lead to fixing the
  problems we have caused.

26
Sampling Techniques in Ecology

• Field research (including remote sensing)
• Observing and measuring actual processes in the
  real- world environment provides the best data.
• Laboratory research
• Small scale experiments under controlled
  conditions simulate larger processes.
• Systems analysis (computer modeling)
• Mathematical models and supercomputer simulations
  predict how ecosystems respond.