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Ecology - PowerPoint PPT Presentation

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Ecology . What is it?. Ecology . Hierarchy of Organization. - Individual. - Population - # of individuals in given area. - Community – all biota in an area. - Ecosystem – all biota & abiotic factors. - Landscape – multiple ecosystems over large area. - Biosphere – all life on Earth.

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What is it?

  • Hierarchy of Organization
  • - Individual
  • - Population - # of individuals in given area
  • - Community – all biota in an area
  • - Ecosystem – all biota & abiotic factors
  • - Landscape – multiple ecosystems over large area
  • - Biosphere – all life on Earth

Autecology: study interrelations of

individuals with environment

Synecology: study of communities

basic scientific principles
Basic Scientific Principles
  • Law of Conservation of Matter
  • Matter cannot be created nor destroyed, rather it can only be transformed
  • 1st Law of Thermodynamics (Energy)
  • Energy cannot be created nor destroyed, rather it can only be converted in form
basic scientific principles6
Basic Scientific Principles
  • 2nd Law of Thermodynamics
  • When converting energy, always lose some energy as heat
major ecosystem processes
Major Ecosystem Processes
  • Energy Flow = energy moves through system

2) Nutrient Cycling = chemical elements recycled in system

energy flow
Energy Flow
  • Solar energy – primary energy source
  • (fig 3.5, p. 42)
  • Of incoming solar radiation:
  • 66% absorbed
  • 34% reflected (albedo)
solar energy
Solar Energy
  • Of solar radiation absorbed:
    • ~22% water cycle
    • nearly all transform to heat & radiates
  • emissivity: relative ability of Earth to release energy (e.g., radiate heat into space; link to global warming)
solar energy10
Solar Energy
  • Tiny amount of solar energy into photosynthesis (< 0.1%)
  • photosynthesis (PNS): use solar energy to convert CO2 & H2O into sugar; by-product = O2
  • primary production: all organic matter resulting from PNS; raw material for other organisms (gross production vs. net production)
energy flow in communities
Energy Flow in Communities
  • food chain: sequence of organisms linked by energy & nutrient flow
  • trophic level: feeding level/position of organism in food chain
trophic levels
Trophic Levels
  • Producer: (autotrophs) anchor of chain; produce all organic matter for other organisms
  • Heterotrophs (consumers)
  • Primary consumer: directly consume producers = herbivores
  • Secondary consumer: consume herbivores
  • Tertiary & Quaternary consumers: consume secondary & tertiary consumers, respectively
trophic levels14
Trophic Levels
  • Decomposers: (detritus feeder) consume and convert dead material for use by producers
food webs
Food Webs
  • food web: interconnected food chains; all trophic interactions in community
human impacts
Human Impacts
  • Ecosystem simplification: elimination of species from food webs via human alterations to land
  • Example: vertebrate communities in ag. landscapes
energy flow between trophic levels
Energy Flow Between Trophic Levels
  • Does 100% of energy transfer from 1 trophic level to another?
  • No. Remember 2nd Law of Thermodyn.
  • Range 5-20% transference (usually ~10%)
  • Graphical representation of energy transference in food web = energypyramid
energy flow between trophic levels24
Energy Flow Between Trophic Levels
  • Why such low efficiency?
  • Three Reasons:
  • 1) Escape behavior/protective coloration/unavailable material
  • 2) Indigestible material
  • 3) Cellular respiration
nutrient cycles
Nutrient Cycles
  • What does the Law of Conservation of Matter state?
  • circular flow of chemicals = recycling
  • Inputs & relationship to energy flow?
  • Water, Carbon (C), Nitrogen (N), Phosphorus (P), Sulfur (S)
carbon cycle
Carbon Cycle
  • Carbon = building block of life
  • Reservoirs = atmosphere, ocean, organisms
  • High rate of exchange in/out reserves
  • Any relation to global warming?
nitrogen fixation
Nitrogen Fixation
  • Types
  • 1) atmosphericfixation via lightening or sunlight; NO3 as precipitation (ppt)
  • 2) biologicalfixation* via soil & water bacteria (blue-green algae); NH3; legumes & root nodules
  • Water Quality & Nitrates
  • Soil Condition & Fertilizers
phosphorus cycle
Phosphorus Cycle
  • Water Quality & Phosphorus
  • Eutrophication: increase in nutrient content of lakes
some ecological principles
Some Ecological Principles
  • Individual
  • Law of Tolerance: organisms can tolerate a range of conditions beyond which they die
  • e.g., temperature, nutrients
  • age-dependent, DNA
where does habitat fit
Where does habitat fit?

Habitat: home; area having necessary resources (food, water, cover) and environmental conditions (temp., ppt) that allows organism to live & reproduce

Your habitat = ?????

What if habitat is drastically changed or destroyed?

  • Move, Adapt, or Die
properties of communities
Properties of Communities

1) Species Richness = # species in a comm.

2) Species Evenness = relative abundance of different species

3) Species Diversity = richness & evenness

e.g., Four species (A,B,C,D) in 2 different communities

Comm 1 – 25A 25B 25C 25D

Comm 2 – 97A 1B 1C 1D

what happens in a community
What Happens in a Community?

1) Competition: individuals contest over a resource (food, space, water, mates…) – major factor determining structure

what happens in a community37
What Happens in a Community?

Types of Competition

A) Interspecific: competition between different species, e.g., blue jay & chickadee compete for sunflower seed at feeder

what happens in a community38
What Happens in a Community?

Types of Competition

B) Intraspecific: competition within the same species, e.g., 2 oryx bobcats compete for space

principle of competitive exclusion gause s experiments
Principle of Competitive Exclusion (Gause’s experiments)
  • Two species which compete for same resource cannot coexist in same place at same time
  • Implications = different locations or different times
  • Relates directly to niche concept
niche concept
Niche Concept

Niche: functional role (“occupation”) & position (spatial & temporal) of a species in its community

  • Principle of Competitive Exclusion = 2 species cannot occupy the same niche
what happens in a community cont
What Happens in a Community? (cont.)

2) Predation: one species consumes another species

some ecological principles42
Some Ecological Principles
  • Community
  • Biological Succession: temporal sequence of one community replacing another; predictable
  • Primary vs. Secondary
terrestrial biomes
Terrestrial Biomes
  • Biomes - distinguished primarily by their predominant plants and associated with particular climates.
    • Geographic and seasonal variations in temperature and precipitation are fundamental components.
soil foundation of terrestrial biomes
Soil : Foundation of Terrestrial Biomes
  • Soil is a complex mixture of living and non-living material.
    • Classification based on vertical layering (soil horizons)
      • Soil Profile = snapshot of soil structure in a constant state of flux
soil horizons
Soil Horizons
  • O horizon: Organic Layer freshly fallen organic material - most superficial layer
  • A horizon: Mixture of minerals, clay, silt and sand
  • B horizon: Clay, humus, and other materials leached from A horizon - often contains plant roots
  • C horizon: Weathered parent material
tropical rainforests
Tropical Rainforests
  • Little temperature variation between months
  • Organisms add vertical dimension
  • Harbor staple foods and medicines for world’s human populations - increasingly exploited
tropical dry forest
Tropical Dry Forest
  • Climate more seasonal than tropical rainforest
  • Heavily settled by humans with extensive clearing for agriculture
tropical savanna
Tropical Savanna
  • Climate alternates wet / dry seasons
    • Fire dependent

~ 20% of earth’s land surface

  • Water loss usually exceeds precipitation
  • Human intrusion increasing
mediterranean woodland shrubland chaparral
Mediterranean Woodland & Shrubland (Chaparral)
  • All continents except Antarctica
  • Climate cool & moist in fall, winter, and spring; hot & dry in summer
  • Fire-resistant plants due to fire regime
temperate grassland
Temperate Grassland
  • Periodic droughts
  • Soils tend extremely nutrient rich and deep
  • Dominated by herbaceous vegetation
  • Warm season grasses

(tall grass vs. short grass)

  • Large roaming ungulates
    • Bison vs. cattle
temperate forest
Temperate Forest
  • Fertile soils
    • Long growing seasons dominated by deciduous plants
    • Short growing seasons dominated by conifers
  • Many major human population centers
boreal forest taiga
Boreal Forest (Taiga)
  • Northern Hemisphere
    • ~ 11% of earth’s land area
  • Thin, acidic soils low in fertility
  • Generally dominated by evergreen conifers
  • Historically, low levels of human intrusion
  • Covers most of lands north of Arctic Circle
    • Climate typically cool & dry; short summers
  • Low decomposition rates
  • Human intrusion historically low, but increasing as resources become scarce
    • What type of increased use?
who cares
Who Cares?
  • Why bother discussing these models?
  • Metapopulations & Source-sink Populatons highlight the importance of:
  • habitat & landscape fragmentation
  • connectivity between isolated populations
  • genetic diversity
habitat fragmentation
Habitat Fragmentation
  • Process of breaking contiguous unit into smaller pieces; area & distance components
  • Leads to:
    • < remnant patch size
    • > edge:interior ratios
    • > patch isolation
    • < connectivity
  • Community & Ecosystem processes altered
habitat fragmentation62
Habitat Fragmentation
  • First-Order Effects: fragmentation leads to change in a species’ abundance and/or distribution
  • Higher-Order Effects: fragmentation indirectly leads to change in a species abundance and/or distribution via altered species interactions
habitat fragmentation63
Habitat Fragmentation
  • area-sensitive species: species that require minimum patch size for daily life requirements
  • Edge effects: influence of factors from outside of a patch
edge effects
Edge Effects
  • Habitat surrounding a patch can:
    • change abiotic conditions; e.g., temp.
    • change biotic interactions, e.g., predation
  • Example of nest predation = edge effect of approximately 50 m into forest patch
conservation implications
Conservation Implications
  • All habitats are “islands”
  • The “internal external threat”
  • Develop & manage reserve as landscapes/ecosystems linked by movement of species (metapop. concepts)
  • Develop strategies for countering edge effects……predator control?????