Ecosystems

1
Ecosystems

• Starr/Taggarts
• Biology
• The Unity and Diversity of Life, 9e
• Chapter 49

2
Ecology Defined

• Ecology the study of organisms and their
  interactions with each other and the environment

3
Introduction to Ecosystems

• An ecosystem is an complex unit of organisms
  interacting with each other and their environment
• Ecosystems are open systems through which energy
  flows and materials are cycled.
• Ecosystems require energy and nutrient input and
  generate outputs of both energy (heat usually)
  and nutrients
• Energy flows in only one direction through an
  ecosystem
• Autotrophs are primary producer organisms for the
  ecosystem

4

• Note the input
• Note the organisms
• Note the output
• Note the one way energy flow
• Note the cycling

Fig. 49.2, p. 876
5
Habitats

• A habitat is a place where an organism lives
• A community is an association of interacting
  populations of different species

6
Factors shape the structure of a community

• Factors are both abiotic and biotic.
• Abiotic
• Rainfall
• Temperature
• soil
• Biotic
• Food available
• Organism interactions

7
Rainshadow Effect
Winds carry moisture inland from Pacific Ocean
Clouds and rain on windward side of mountain range
Rainshadow on leeward side of mountain range
Fig. 50.7, p. 901
8
Abiotic and Biotic Interplay
Fig. 50.11, p. 903
9
Community Properties

• There are feeding levels from producers to
  consumers
• The number of species present is the species
  richness
• Relative abundance refers to the number of
  organisms of a species and dispersion refers to
  their dispersal through the habitat.

10
The Niche

• The niche of an organism is its role in the
  ecosystem in other words the sum of its
  activities and relationships
• There is a difference between the potential niche
  (no competition) and the realized niche

11
Overview of Participants
Parasites??
Fig. 49.7, p. 879
12
Structure of Ecosystems

• Trophic Levels (feeding levels)
• 1st - Primary producers
• Autotrophs
• 2nd - Primary consumers
• Herbivores, Decomposers, Detritivores
• 3rd - Secondary consumers
• Primary carnivores
• 4th - Tertiary consumers
• Secondary carnivores and parasites

13
Trophic Levels
Fig. 49.4, p. 877
14
Food Webs

• Sequence of who eats whom is called a food chain
• Interconnected food chains comprise food webs

Fig. 49.5, p. 878
15
Food Webs
Fig. 49.6, p. 878
16
Label the Organisms
Fig. 49.27, p. 894
17
Organism Interactions

• Neutral relationships neither species affect one
  another
• Commensalism /neutral
• Mutualism /
• Interspecific and Intraspecific Competition -/-
• Predation and Parasitism /-

18
Pyramid of Biomass
Top carnivores
Decomposers
Primary carnivores
Herbivores
Primary Producers
19
Energy Pyramid

• Units kilocalories/meter squared/year

10 Rule!!!
20

• Note the conservation of energy!
• Primary Productivity
• Gross PP total rate of photosynthesis during a
  period of time
• Net PP rate of energy storage in plant tissues
  in excess of the rate of respiration

Fig. 49.12, p. 882
21
DMA (200 to complete)

• Please number your 3rd Quarter DMAs and then
  staple them and hand them in in a neat pile.

22
Announcements/HW

• HW tonight
• Chapter 46 reading
• Spring Break assignment (due Monday!)
• Timed essay 1 and 2
• Reminders
• Saturday Lab Review 9 AM

23
Biogeochemical Cycles
Fig. 49.13, p. 884
24
Biogeochemical Cycles

• Influence the availability of essential elements
  in ecosystems
• Nutrients available to producers as ions
• Reserves maintained by environmental inputs and
  recycling activities
• Cycling gt input or output
• Inputs precipitation, metabolism, weathering
• Outputs runoff and evaporation

25
Biogeochemical Cycles
Fig. 49.13, p. 884
26
Three Categories

• The categories of biogeochemical cycles
• Hydrologic cycle (O and H as well as H2O)
• Atmospheric cycles (C and N)
• Gaseous phase
• Sedimentary cycles (P)
• No gaseous phase

27
Hydrologic Cycle

• Water is moved by
• Evaporation
• Precipitation
• Retention
• Transportation
• Water moves other nutrients into and out of
  ecosystems
• A watershed funnels rain or snow into a single
  river
• Nutrients are absorbed by plants to prevent their
  loss by leaching

28
ATMOSPERE
PRECIPITATION onto land 23
HORIZONTAL TRANSPORT of water vapor 7
EVAPORRATION from land plants (evapotranspiration)
16
EVAPORRATION from ocean 84
PRECIPITATION into ocean 77
SURFACE AND GROUNDWATER FLOW 7
LAND
OCEAN
Fig. 49.15, p. 884
29
Experimental Watershed

• Deforested area had greater calcium loss than
  undisturbed area

30
Carbon Cycle

• C (CO2) enters the atmosphere via
• Aerobic respiration
• Fossil fuel burning
• Volcanic eruptions
• C removed from atmosphere and bodies of water by
• Photosynthesizers
• Shelled organisms
• Decomposition of buried C resulted in fossil fuel
  formation
• Burning of fossil fuels leads to increase CO2 and
  the greenhouse effect

31
C Cycle in the Ocean
Fig. 49.17, p. 886-87
32
C Cycle Over and In Land
Fig. 49.17, p. 886-87
33
Carbon Cycle

• Aerobic respiration ------gt CO2
• Fossil fuel burning
• Volcanic eruptions
• Atmosphere, soils, plant biomass
• Largest holding stations for Carbon
• CO2 - fixation
• Photosynthetic autotrophs

34
Greenhouse Gases and a Warmer Planet

• Greenhouse effect
• CO2, Ozone, Methane, Nitrous oxide, CFCs

Fig. 49.19, p. 888
35
Greenhouse Gases
Fossil Fuel burning Deforestation
36
Global Warming

• Atmospheric CO2
• Glaciation and Interglacial Periods

37
Nitrogen Cycle

• N2 gases converted to usable forms

38
GASEOUS NITROGEN (N2) IN ATMOSPHERE
NITROGEN FIXATION by industry for agriculture
FOOD WEBS ON LAND
uptake by autotrophs
excretion, death, decomposition
uptake by autotrophs
FERTILIZERS
NO3- IN SOIL
NITROGEN FIXATION bacteria convert to ammonia
(NH3) this dissolves to form ammonium (NH4)
NITROGENOUS WASTES, REMAINS IN SOIL
DENTRIFICATION by bacteria
2. NITRIFICATION bacteria convert NO2- to nitrate
(NO3-)
AMMONIFICATION bacteria, fungi convert the
residues to NH3 this dissolves to form NH4
NH3-, NH4 IN SOIL
1. NITRIFICATION bacteria convert NH4 to nitrate
(NO2-)
NO2- IN SOIL
loss by leaching
loss by leaching
Fig. 49.22, p. 890
39
Human Intervention in the Nitrogen Cycle

• Air pollutants contribute to soil acidity
• Nitrogen Scarcity
• N fixing bacteria add N compounds to the soil
• Scarcity caused by
• Leaching
• Denitrification
• Farming methods

40
Sedimentary Cycle

• Phosphorus Cycle
• From land to sediments at bottom of the sea then
  back to land
• Ecosystem phase
• Plants take P from soil
• Animals eat plants and get the P
• Excreted and leaves decomposing bodies
• Earths Crust
• Largest reservoir of phosphorus

41
mining
FERTILIZER
excretion
GUANO
agriculture
weathering
uptake by autotrophs
uptake by autotrophs
weathering
LAND FOOD WEBS
DISSOLVED IN OCEAN WATER
MARINE FOOD WEBS
DISSOLVED IN SOILWATER, LAKES, RIVERS
death, decomposition
death, decomposition
leaching, runoff
sedimentation
setting out
uplifting over geolgic time
ROCKS
MARINE SEDIMENTS
Fig. 49.24, p. 892
42
Eutrophication

• Activities that increase the concentration of
  dissolved nutrients
• Nutrient enrichment of any aquatic ecosystem
• Most minerals enter sedimentary cycles
• Fertilizers use phosphates
• Dense algae blooms

43
Ecosystem Modeling

• Prediction of unforeseen effects of disturbance
• Computer programs and models
• Case Study
• DDT - mosquito control
• Biological magnification
• Higher trophic organisms have higher
  concentrations