1. Ecosystem Processes and
Biomes

2. Overview
Describing Life on Earth
Taxonomic Hierarchy
Classifying species
Biogeographical Realms
Trophic Hierarchy
Energy and nutrient flow
Food chains and Food webs
Nutrient Cycles
Ecological Hierarchy
Communities and Assemblages
Stability, succession and disturbance
Terrestrial Ecosystems
Biomes
Biomes
Formation classes

3. Biogeography: the study of the
distributions of plants and animals and
related ecosystems; the geographical
relationships with their environments
over time

4. The Biosphere
The biosphere encompasses all of the living
species on earth (Biodiversity)
What the species are
How they interact with each other
How they are distributed over the globe
Scientific perspectives derive from
Evolutionary theory
Genetic relationship between species
Natural selection
Interaction with each other through competition for resources
Ecology
Co-occurrence of species in given areas
Competition (especially in food chains) regulates the flow of
energy through
Global classification based on
Evolutionary linkages (Realms and Regions)
Ecological relationships (Biomes)

5. Hierarchies of Life
Biodiversity is shaped by the
interactions of species that result in the
formation of stable groups (or unstable
groups) of species through the
regulation of the flow of energy and
nutrients.
Taxonomic hierarchies
organization of related species
Trophic hierarchies
organization of energy and nutrient flow
Ecological hierarchies
organization of species into groups

6. Taxonomic Hierarchy
Taxonomy: the systematic classification of
plants, animals and other life forms according
to presumed natural relationships
Taxon: a group or entity within a
classification system (pl. taxa)
Species specific
Genus
Family
Order
Class
Phylum
Kingdom general
Groupings based on identified evolutionary
relationships

7. Species are classified according to:
Morphology – similarity of physical and behavioral
traits
Reproductive criteria
genetic relationships
Species named with Latin binomials,
according to taxonomic criteria
Genus + Specific epithet
Example: Genus Syzygium
Syzygium inophylloides
S. samarangense
S. dealatum
S. savaiiense
Groupings into similar genera and families implies
evolutionary linkage

8. Kingdoms
Kingdom Monera (prokaryotic bacteria and
cyanobacteria)
Kingdom Protista (eukaryotic single-cell
organisms; protozoa, amoebas,
multicellular algae)
Kingdom Myceteae: fungi
Kingdom Animalia: animals
Kingdom Plantae: plants
Links (1)

9. Kingdom Plantae: Phyla
Bryophyta: mosses
Pteridophyta: ferns
Coniferophyta: conifers (gymnosperms)
Anthophyta: flowering plants
(angiosperms)
monocotyledons
dicotyledons
Others

10. Kingdom Animalia
Invertebrates
Arthropods (Insects, spiders, mites, crustaceans)
Mollusks
Flatworms
Roundworms
Earthworms
Jellyfish, corals
Starfish, sponges
Vertebrates
Fish
Amphibians
Reptiles
Birds
Mammals

11. There are roughly 1.8 million known species
on Earth
Estimates on total species vary between 4 million
and 20 million
Taxonomic distribution
56% Insects
Beetles (Coleoptra) comprise 24% of the total
17% Other arthropods and invertebrates
14% Plants
9% Algae, protozoans, fungi
2.7% Vertebrates
1% Bacteria and viruses

12. Numbers of described species by major taxa
Insecta: 751,000
Plantae (Multicellular plants): 248,428
Non-insect arthropoda (mites, spiders, crustaceans): 123,151
Mollusca: 50,000
Fungi: 46,983
Protozoa: 30,800
Algae: 26,900
Pisces (fish): 19,056
Platyhelminthes (flatworms): 12,200
Nematoda (roundworms): 12,000
Annelida (Earthworms): 12,000
Aves (Birds): 9,040
Coelenterata (Jellyfish, corals): 9,000
Reptilia: 6,300
Echinodermata (starfish, etc.): 6,100
Porifera (sponges): 5,000
Monera (Bacteria, blue-green algae): 4,760
Amphibia: 4,184
Mammalia: 4,000

13. Biogeographic Realms
Realms
As continental masses separated off from
each other, their isolation from each other
allowed their species to evolve separately,
giving rise to unique assemblages
Oceans form main barrier to spread, but also
mountains, climatic conditions

16. Trophic Hierarchy
Organizing life according to the flow of energy
Solar energy
Critical role of plants: photosynthesis
trophic levels, foodchains, efficiency, food
pyramids
Producers: plants (autotrophs)
Consumers (heterotrophs)
Primary consumers: herbivores
Secondary consumers: carnivores
Tertiary consumers: higher order carnivores, omnivores
Food Chains & Food webs
Chains indicate linear pathways of energy flow
(single path)
Food webs illustrate complex multiple pathways
Efficiency: Loss of energy at each level

18. Abiotic Components
Light: photoperiod
Climate: temperature and water
Altitudinal zones (life zones)
Increases in altitude mimic increases in latitude
Normal lapse rate: temperatures cool with
increasing altitude: changing climatic patterns
Elemental cycles (biogeochemical cycles)
Nitrogen cycle
Carbon and oxygen cycle
Limiting factors: an abiotic or chemical factor
that is in short supply and inhibits ecosystems
from operating at full potential.

19. Trophism
Producers, consumers, detrivores, decomposers
Food chains and food webs
Trophic levels
Producers
plants
Primary consumers
herbivores
Secondary consumers
carnivores
Tertiary consumers
higher level carnivores

20. Critical Role of Plants
A vital link between the abiotic and biotic
components
with help from soil biota
Photosynthesis
Stores Carbon dioxide, water, and energy
Creates Carbohydrates and oxygen
6CO2 + 6H2O C6H12O6 + 6O2
Respiration
Releases stored energy, carbon dioxide and water vapor
C6H12O6 + 6O2 6CO2 + 6H2O
Plants also intercept Nitrogen, a building block of
proteins
Net Primary Productivity: photosynthesis usually
exceeds respiration.

22. Net primary productivity results in increased biomass
Biomass: net dry weight of organic material

28. Consider also grass-fed beef; although similar inefficiencies exist,
people cannot directly digest grass. In areas where agriculture is
not viable, this makes ecological sense.

29. Nitrogen Cycle, Revisited

30. Carbon cycle, revisited

31. Ecological Hierarchy
Organization of life according to number of
species and spatial scale
Individual Species
Individual
Population
Metapopulation
Community
Assemblages
Guilds
Ecosystem: communities plus trophic interactions
Biomes: ecosystems on a global scale,
differentiated by levels of abiotic inputs and
primary productivity
Biosphere

32. Ecosystems
Ecosystem: a self-regulating
association of plants, animals and
physical environment
Ecology: the study of the various
interactions between components
of the environment

33. Ecosystem Components
Ecosystems have biotic and
abiotic components
Abiotic:
solar energy input
nutrient cycles
nitrogen
carbon

34. Biotic
Communities
an assemblage of interacting plants and animals
Competition
Mutualisms
Habitat
the type of environment that a particular species lives in and is
adapted to.
Some species are adapted to one type of habitat
“habitat specialists”
Some species are adapted to several habitats
“habitat generalists”
Niche: the functional role a species plays in its community
Habitat niche
Trophic niche: producer, consumer, decomposer
Reproductive niche
Competitive exclusion principle
An ecosystem is most stable when all of its niches are filled

35. Range and Distribution
The distribution of the abiotic resources that
a species needs affects where that species
can occur
Climatic factors are important determinants of
range
Species that are limited to one or a few areas
are referred to as endemics
These species are often highly specialized to a
particular niche
Often the most efficient competitor for that niche,
but are susceptible to change
Generalist species often have a much greater
spatial range than specialized species, and
are more tolerant of change

38. Stability, Succession, Disturbance
Basic Concepts
Stability: ability of a community to retain its species
composition: most stable when all niches are filled
Climax community
Resilience: ability of a community to recover its
original species composition after a disturbance
Biodiversity: the number and abundance of species in
an area
Disturbance: an event that alters community
composition, re-allocates stored nutrients, and alters
nutrient pathways
Succession: changes in species composition in a
community over time as the community moves toward
stability following a disturbance
Biodiversity and stability
High native biodiversity conveys ecosystem stability
Prevent loss of energy and nutrients

39. Disturbance
When a disturbance is small in comparison to the
community in question, the community quickly
reincorporates the disturbance and reestablishes
stability
Example: tree fall, creating gaps in forest canopy
When a disturbance is larger than a community
and occurs relatively frequently, the type of
disturbance structures the community composition
“Disturbance Regime”
Examples: Hurricanes, fire ecology
When a disturbance is of similar spatial scale and
occurs with a frequency comparable to succession
rates, transformation of ecosystems can occur

42. Ecological Succession
Patch Dynamics
Succession
Seed banks (seeds already present at a location)
Dispersal (seeds transported into a location)
Areas of infrequent disturbance are more likely to return to
original community composition
Areas of frequent disturbance will change composition
toward dispersible species from outside the patch
Terrestrial Succession
Primary Succession
Occurs in areas with no vegetation
example: lava flows
example: surface mining
Species adapted to growing on little or no soil (lichens, mosses)
are often the pioneer species
Secondary Succession
Occurs where disturbance leaves some vegetation
Rapidly dispersing, opportunistic species are frequent pioneer
species

43. Fire Ecology
A disturbance regime
Fire is a “natural” part of many ecosystems
Especially in the western US
Lightning strikes
Native American land management
created a “park-like landscape” that provided habitat for
game
Many tree species are adapted to fire, and require
it to complete their reproductive cycles
Fire suppression allowed accumulation of
fuel, contributing to catastrophic fires
Fire is now used as a management tool

44. Ecosystems and Biomes
Terrestrial Ecosystems
self-regulating assemblages of plant and
animal species interacting with each other
and their abiotic environment
The assemblage of plant species gives
each ecosystem its defining character
provides link between abiotic and biotic
components (distinguishes ecosystems from
communities)
provides habitat and niche

45. Biome: large, stable, terrestrial
ecosystem
Classification based on dominant
vegetation
forest
savanna
shrubland
grassland
desert
tundra
Ecotone: transition zone between biomes
Formation classes: dominant vegetation
within the general biome classes

57. Formation Classes
Equatorial and Tropical Rainforest (ETR)
Tropical Seasonal Forest and Scrub (TrSF)
Tropical Savanna (TRS)
Midlatitude Broadleaf and Mixed Forest (MBME)
Needleleaf Forest and Montane Forest (NF/MF)
Temperate Rain Forest (TeR)
Mediterranean Shrubland (MSh)
Midlatitude Grasslands (MGr)
Warm Desert and Semi-desert (DBW)
Cold Desert and Semi-desert (DBC)
Arctic and Alpine Tundra (AAT)
(Ice)

59. Equatorial and Tropical Rainforest
Occur in tropical areas that receive high amounts
of rainfall regularly throughout the year
High net primary productivity and biomass
Vertical arrangement of ecological niches
Emergent Layer: Intense sunlight, high temperatures,
strong winds, low humidity
Canopy Layer: 90% of species live here; epiphytes,
lianas, primates
Understory: 2 – 15% of sunlight; dark, sparse, shade
tolerant species
Forest Floor: Less than 2% light. Decomposing organic
matter
Oxisols, Ultisols
Represent approximately half of the world’s
remaining forests

65. Tropical Seasonal Forest and Scrub
Also called Moist Deciduous forest
On the margins of tropical rainforests
Seasonal variation in rainfall
Tropical Savanna climate
Tropical Monsoon climate
Semi-deciduous trees
lose their leaves during the dry-season
Oxisols, Ultisols, Vertisols, Alfisols
Caatinga (Brazil), Chaco (Paraguay and
Argentina), brigalow (Australia), dornveld
(South Africa)

66. Tropical Savanna
Transitional between tropical forests and semi-
arid tropical steppes and deserts
Mixture of grasslands and small trees and
shrubs
Herbivores that move in herds are characteristic
of landscapes that are wide open
Fire-ecology disturbance regime
Rainfall only occurs with ITCZ (less than 6 months)
Dry conditions otherwise
xerophytic vegetation
Alfisols, Ultisols, Oxisols

67. Midlatitude Broadleaf and Mixed
Forest
Moist continental climates
humid sub-tropical hot-summer climate
marine west coast climates
cool summer, winter drought climate
Mixture of deciduous and evergreen
species
Community structure greatly altered by
human activity
Ultisols, Alfisols, some Spodosols

68. Needleleaf Forest and Montane
Forest
Also called boreal forests
Taiga in in areas transitional to arctic or subarctic
climates
Humid microthermal climates
Needleaf forests not common in S. Hemisphere
Montane forests found world wide (altitudinal
zonation)
Evergreens
Pine, spruce and fir
Characteristic fauna
Beaver, moose, snowshoe rabbit, lynx, wolverine
Spodosols, Histosols, some Alfisols

70. Temperate Rainforest
Mostly in the Pacific NW of N America
Relatively low diversity of tree species
Tallest trees in the world: Giant Redwoods
(Sequoia sempervirens)
Evergreens, some deciduous
Extremely wet climate
Tongass National Forest, Alaska
The world’s last pristine temperate
rainforest
Spodosols, Inceptisols

71. Mediterranean Shrubland
Mediterranean dry-summer climate
Poleward of subtropical high pressure
cells
Stable high-pressure creates dry conditions
Fire ecology disturbance regime
Sclerophyllous vegetation
hardy, drought resistant shrubs with deep
roots and hard waxy leaves
Chaparral
Alfisols, Mollisols

72. Midlatitude Grasslands
The most heavily human modified biome
mining of Mollisols for agriculture
Very little of this biome left
Fauna also characterized by herding
herbivores
Prairies of the Great Plains, Pampas of
Argentina
Mollisols, Aridisols

73. Warm Desert and Semi-desert
Subtropical high pressure cells create the
dry conditions in these areas
Atacama Desert, Chile
Xerophytic shrubs, succulents, thorn trees
Aridisols, Entisols

74. Cold desert and Semidesert
Higher latitudes than warm deserts
Rainshadows and cold ocean currents
influence the dryness
Sage brush and scrub
Many were former short-grass regions,
transformed by intensive grazing
Aridisols, Entisols

75. Arctic and Alpine Tundra
Northern hemisphere, bordering the Arctic
ocean North of 10o latitude
Tundra vegetation
Mosses, lichens, short grass, some small trees
Alpine tundra: high altitude zonation
Fauna
Lemmings, caribou, musk ox, arctic fox, polar bear
Gellisols, Inceptisols, Entisols
permafrost