Ecology and the Environment
(Chapter 22)
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Background and Historical Development
Attributes of Ecological Systems
Selected Issues – Applied Ecology
Take Home Messages
Take-Home Messages
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Functional unit in ecology is the ecosystem; it is analogous to the
cell
Hierarchy theory and emergent properties is applicable to the
study of ecology
Energetics of ecosystems is driven by (i) principles of
thermodynamics (1st and 2nd Laws) and (ii) nature in which
organisms acquire and utilize energy; result is a predictable pattern
among all ecosystems embodied in the concept of trophic levels
Ecosystems are not static but change over time in predictable and
recurrent ways; this change is called succession
Energy passes through ecosystems unidirectionally, whereas
elements/materials cycle throughout ecosystems
Biodiversity, the number and distribution of species, is an
important feature of ecosystems
Ecologyand the Environment
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Background and Historical Development
Attributes of Ecological Systems
Selected Issues – Applied Ecology
Take Home Messages
Background and Historical Context
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Discipline of ecology
Evolution of the science
Orientation by type of system
Discipline
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1950’s: emergence of the discipline
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Stimulus: technological changes
Harnessing the atom (radioactive elements)
 Rachel Carson’s Silent Spring
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Two sub-disciplines
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Basic ecology
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Structure and function of ecosystems
Applied ecology
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Human-altered and “managed” ecosystems
Evolution
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Early to mid 1900
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> 1950’s
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descriptive natural history
Experimentally and hypothesis driven research
> 2000
Experimentally and hypothesis driven research
 Mathematical modeling at a global scale
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Types of Ecosystems
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Natural ecosystems
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Human-dominated ecological systems
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Grasslands, unmanaged forests, wetlands, rivers, etc.
Key: ecological systems that are largely unmanaged for human
use
Agroecosystems, managed forest (timber), fish farms,
urban/suburban landscapes, etc.
Key: ecosystems that are harvested by humans and are
subsidized (fertilizer, water, pest management, etc.)
Attributes in common
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Same basic structure and function (principles are the same)
Attributes
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Ecosystem (ecological system)
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Ecology
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Background and Historical Development
Attributes of Ecological Systems
Selected Issues – Applied Ecology
Take Home Messages
Attributes
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Ecosystem
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Ecosystems
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Ecological systems – ecosystem
Components
 Biotic components
 All living organisms – plants, animals and
microbes
 Abiotic components
 All non-living components – soil, atmosphere,
water, climate, etc.
Ecosystem
 Fundamental unit of ecology; analogous to that of
the cell
Hierarchy Theory and Emergent
Properties
Earth
Biosphere
Biome
Ecosystem
Community
Population
Organisms
Terms
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Population: assemblage of individuals of the
same species in the same area
Community: assemblage of all species in a given
area
Biome: large regional units of several different
types of ecosystems existing in same general
area
Biosphere: all of the Earth’s biomes at the
global scale (shuttle frame of reference)
Major Biomes
Emergent Properties
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Hierarchy theory and emergent properties
Relate to ecology
Emergent properties
Water (combination of H and O)
 Sodium chloride (combination of Na and Cl)
 Mixes species forest (combination of 50+ different
species of trees, shrubs, microbes and animals)
 Unanticipated properties
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Attributes
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Ecosystem (ecological system)
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Structure of Ecosystems
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Structure is underpinned by flow of energy
Autotrophs: fix energy from sun - plants
Heterotrophs: consume energy in C-C bonds
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Primary consumers - herbivores
Secondary consumers – carnivores and omnivores
Tertiary consumers – saprovores (dead organic matter)
All organisms are classified by their source of energy
Trophic Levels of an Ecosystem
Attributes
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Ecosystem (ecological system)
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Energetics of Ecosystems
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Common theme/attribute to all ecosystems
Linkage to physics
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1st Law of Thermodynamics (conservation)
2nd Law of Thermodynamics (entropy increases)
Highly order state of all ecosystems is function of
transforming energy in trophic structure
Thermodynamics: dissipation of energy is most
common in form of heat and respiration
Keys to Energetics
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Energy flows through ecosystems
unidirectionally
As energy flows, amount of energy available to
do work (potential energy in C-C bonds)
decreases
Flow of energy places constraints on the
number of organisms that can exist in higher
trophic levels
Quantification of Energy Flow
10%
2nd Consumers
10%
10 Consumers
10%
1%
Autotrophs
Sun
Respiration and heat
30 Consumers
Trophic Levels of an Ecosystem
Attributes
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Ecosystem (ecological system)
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Biodiversity
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Diversity of world’s biota: ~100 Million species,
of which 1.5 Million have been catalogued
Biodiversity: measurement of the diversity of
flora, fauna and microbes
 Species richness (number of species)
Biodiversity
Biodiversity: Arid Landscaspes
Biodiversity: Significance
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Humanistically: intuitively value (appreciate diversity of
life forms)
Ecologically: evidence that biodiversity is related to
stability and functioning of ecosystems
Declining biodiversity with human population
Attributes
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Ecosystem (ecological system)
Hierarchy theory and emergent properties
Structure of ecosystems
Energetics of ecosystems (flow of energy)
Biodiversity
Cycles of materials and elements
Cycling of Elements and Materials
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Unlike energy, elements and materials cycle
throughout ecosystems and they are re-used
Examples: water, carbon, nitrogen
Path is commonly circular passing from
biosphere to geosphere to hydrosphere to
atmosphere
Basic Cycling Model
Atmosphere
Biosphere
Hydrosphere
Geosphere
Cycling of Elements: Nitrogen
Ecology
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Background and Historical Development
Attributes of Ecological Systems
Selected Issues – Applied Ecology
Take Home Messages
Human Population Growth
o
Selected Issues in Ecology
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Acid rain
Biodiversity and habitat loss
Climate change – a global issue
Ozone and particulate matter in the atmosphere
Stratospheric ozone and UV-B radiation
 Tropospheric ozone and human health
 PM and human health
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Take-Home Messages
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Functional unit in ecology is the ecosystem; it is analogous to the
cell
Hierarchy theory and emergent properties is applicable to the study
of ecology
Energetics of ecosystems is driven by (i) principles of
thermodynamics (1st and 2nd Laws) and (ii) nature in which
organisms acquire and utilize energy; result is a predictable pattern
among all ecosystems embodied in the concept of trophic levels
Ecosystems are not static but change over time in predictable and
recurrent ways; this change is called succession
Energy passes through ecosystems unidirectionally, whereas
elements/materials cycle throughout ecosystems
Biodiversity, the number and distribution of species, is an
important feature of ecosystems