Biomes
Weather - particular set of physical properties of
the Earth’s troposphere:
–Temperature, pressure, humidity, precipitation, sunshine,
cloud cover, wind direction and speed
Climate – a region’s general pattern of
atmospheric or weather conditions, including
seasonal variations and weather extremes over a
long period.
Biome – a large geographical region having a
defining climate to which plants show a similar
physiological adaptation.
Four Global Temperature Regimes
Hot
• Tropical
• Temperate
• Subpolar
Cold
• Polar
Four Plant Types
• Succulent – vertical orientation on most parts, no
leaves, store water, photosynthesis in tissue
– Cactus
• Broadleaf Evergreen – keep most of their broad
leaves year-round
– Tropical trees
• Broadleaf Deciduous – drop their leaves when it
gets cold (dry in the tropics)
– Oak, maple, pecan
• Coniferous (cone-bearing) Evergreen Plants – keep
their narrow pointed leaves (needles) all year
– Pine, spruce, fir
General Biome Types
• Forest – dominated by trees
– A lot of precipitation needed
• Scrubland – small deciduous trees and shrubs
– Some precipitation needed
• Grassland – dominated by grasses
– Does not need as much precipitation as a forest
– Usually needs disturbance to limit tree growth
• Grazing, fire
• Desert – dominated by succulents
– Very little precipitation
‘For plants, precipitation generally is the limiting factor that
determines whether a land area is desert, grassland, or forest.’
Temperature and precipitation
regulate plant growth, thus the
regional distribution of biomes.
Boundary lines between
biomes are not as distinct
as implied here.
Tropical, Temperate, or polar – Depends on Temperature
Forest, Grassland, or Desert – Depends on Rainfall
Global air circulation
affects local precipitation
Cold, dry
air falls
Cell 3 North
Moist air rises — rain
Polar cap
Cell 2 North
Arctic tundra
Evergreen
60° coniferous forest
Temperate deciduous
forest and grassland
Desert
30°
Tropical deciduous
forest
Tropical
0° Equator rain forest
A combination of insolation
and precipitation
determines global biome
distribution
Cool, dry
air falls
Cell 1 North
Tropical deciduous forest
30°
Desert
Temperate deciduous
forest and grassland
60°
Cell 1 South
Cool, dry
air falls
Cell 2 South
Polar cap
Cold,
dry air
falls
Moist
air rises,
cools, and
releases
moisture
as rain
Moist air rises — rain
Cell 3 South
Net Primary Production of Terrestrial Biomes
Biome
NPP (g C/m2/yr)
Tropical Rain Forest
900
Tropical Dry Forest
675
Temperate Evergreen Forest
585
Temperate Deciduous Forest
540
Boreal Forest
360
Tropical Grasslands
315
Cultivated land (USA)
290
Chaparral
270
Prairie
225
Tundra
225
Desert
32
Extreme Desert
1.5
Rivers and Streams
• Generally represent the excess of precipitation
on land areas over evaporation from them.
– Precipitation that falls is either evaporated,
transpirated, enters the ground water supply, or
flows down rivers
• Flow is down-hill and varies seasonally
– Related to rainfall and ice/snow melt
• Beginning of a river = the source and the end of a
river = the mouth
• Discharge - volume of water passing a given
point during a period of time
– Channel Width X Depth X Velocity
Rivers and Streams
• Flow velocity is important in determining
abiotic and biotic components.
– Flow related to slope and precipitation
– Sediment type, current strength
– The faster the flow, the more material can be
transported in the water
– Only certain organisms can withstand strong
flow
• Materials are transported by running water
in three principal states
– Dissolved matter
– Suspended solids
– Bed load
Stream Order
Used to classify a
stream in relation to
tributaries, drainage
area, total length,
and age of water.
11=2
12=2
22=3
13=3
23=3
1
1 1
1
2
2
1
33=4
Mississippi River is
classified as a 10th
or 12th order stream.
Headwater stream
classification
Stream Order – Strahler Method
matters
3
2
Major Rivers of The World
Discharge
103 m3/sec
Length
103 km
Drainage Area
106 km2
Amazon, South America
212.40
6.44
5.78
Congo, Africa
39.65
4.70
4.01
Ganges-Brahmaputra, India
38.50
2.90
1.62
Yangtze, China
21.81
5.98
1.94
Yenisei, USSR
17.39
5.54
2.59
Mississippi North, America
17.30
6.02
3.22
Mekong, Asia
11.04
4.00
0.80
Nile, Africa
3.10
6.65
3.35
Name
You will be required to draw a map of the major rivers
of the Mississippi River Basin as part of exam 1.
Distributary – A smaller channel
that takes water away from the
main stem river.
Flow
Mississippi River
(Main Stem)
Atchafalaya River
(Distributary)
Large River Floodplain Ecology
Construction of levees
along the Mississippi
River and many of its
tributaries has severed
the river from over 90%
of its floodplain,
denying fish and other
aquatic species access
to millions of acres of
foraging, spawning and
nursery habitat.
Miss. Dept. of Archives
and History
Miss. Dept. of Archives
and History
http://www.lmrcc.org/ARMP%20folio.pdf
Net Primary Production (measure
of available energy)
Estuaries
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest (taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Lakes and streams
Continental shelf
Open ocean
Tundra (arctic and alpine)
Desert scrub
Extreme desert
800
1,600
2,400
3,200
4,000
4,800
5,600
6,400
7,200
Average net primary productivity (kcal/m2/yr)
8,000
8,800
9,600
Where Are We?
Ponchartrain
Atchafalaya
N
Terrebonne
Barataria
Terrestrial Vegetation Growth During
Low Water
Nutrients Released During
High Water
Simply put:
More Nutrients = More Plants = More Animals
= Happy Cajuns!!
Inundation of the floodplain is the
mechanism of energy and nutrient
transfer from terrestrial vegetation
to the aquatic community.
Swamps are not wastelands!
The Floodplain Extends to the Coast
• All flowing Louisiana waterways eventually drain
to the Gulf of Mexico
• Energy and nutrients from floodplain terrestrial
vegetation are carried to coastal waters and
sustain estuarine and coastal production
• The coast is ultimately supported by floodplain
ecosystem processes
Baton Rouge
New Orleans
Thibodaux
Houma
Port Sulphur
Grand Isle
Three General Types of Water
• Brown
– High flow, lots of sediment, fairly high oxygen
levels, riverine
• Green
– Low flow, stratification, very high surface
oxygen levels, highly productive, lacustrine
• Black
– Low flow, very low surface oxygen levels, not
productive, swamp
Backwater
December
June
August
Interior Lakes
Mainstem
Oxygen Level Controls
Photosynthesis produces oxygen:
Solar Energy + CO2 + H20  C6H12O6 + O2
Respiration consumes oxygen:
C6H12O6 + O2  CO2 + H20 + chemical energy(ATP)
What is Hypoxia
• Dissolved Oxygen (DO) less than 2.0 mg/L
• Normoxic = DO > 2.0 mg/L
• Generally, most fish can not tolerate
hypoxic conditions for long periods.
– Gar, bowfin (choupique), bullheads can
Why Hypoxia?
• During low water times, the
dry lands are extremely
fertile and grow a lot of
plants.
• When the spring floods
come and temperatures
rise, bacteria begin to
decompose the vegetation
on the floodplain floor.
• Bacterial respiration is what
removes the oxygen (lack
of flushing in backwater
habitats contributes).
• Respiration rates exceed
photosynthetic rates.
When and Where Is Hypoxia?
• Generally found during high water times
when temperatures are warm.
• Backwater areas (away from the mainstem
river).
– Low flow
Eventually the
swamp drains
and backwater
areas become
very productive.
How Do ‘Unproductive’ Areas
Support Living Populations?
• Submerged Aquatic Vegetation
– Oxygen Refuge
– Productive microhabitats
Fish and Aquatic Vegetation
• Densities of young
fish are often greater
in aquatic vegetation
than in adjacent
open water
Mean Surface Dissolved Oxygen in Open
Water and Plants at Each Site
Dissolved Oxygen (mg/L)
16
Green
14
12
Brown
10
Black
Open
8
Plant
6
4
2
0
GLN
GLS
INT
Normoxic
FL
BL
SOC
Hypoxic
Air-Water Interface
Atmospheric oxygen
diffuses into water
Fish ‘pipe’ at the
microsurface layer
Low DO Water
How Do ‘Unproductive’ Areas
Support Living Populations?
• Detritus-Based Production
– Decomposers (e.g., bacteria) transfer energy
stored in old organic matter to consumers
• Insects, crawfish
– Low-oxygen tolerant organisms
• Gar, bowfin (choupique), bullheads
Energy flow through
an aquatic ecosystem.
From Cole 1988, Waveland Press
Terrestrial leaf
litter/detritus
input during
Flood Pulse
Detritus Based Food
Web.
From Cole 1988, Waveland Press
Major Ocean Currents Effect on Climate
• Insolation (and associated effects), the
Earth’s rotation, plus difference in water
density, create warm and cool currents.
Ocean
currents can
affect local
climate
Oceans
• Coastal regions are much more productive
than non-coastal areas.
– Rich nutrient input from coastal rivers
– Most of the worlds great fisheries come from
the continental shelf
– Too many nutrients can lead to algal blooms,
which may deoxygenate the water
(eutrophication)
Oceans
• Salinity averages 35 ppt (full strength sea water).
– Due to high concentrations of sodium and chloride
• Ocean is more than salt and water, but most
ocean waters are very poor in nutrients
– Phosphate, nitrate, ammonium, iron
• Oceans cover ~71% of Earth, but only account for
50% of the Earth’s primary production.
– Biological deserts not limited by water, but by nutrients
– Unlike terrestrial biomes, production is not higher at
equator and lower at the tropics –respond to nutrient
concentrations like upwellings.
Upwelling Productivity
Global estimates of
the primary
production required
to sustain fisheries in
five marine
ecosystems.
Production is highest
in shallow well-lit
coastal waters and
upwellings.
Upwelling Productivity
• Primary production dependent on nutrients
brought from the ocean depths.
– This is a function of ocean currents driven by wind
pattern and the Earth’s rotation
• A disturbance to wind patterns can affect the
primary production of upwellings, which can have
an effect ‘up the food chain.’
Productivity
• Aquatic Productivity relies on nutrient
input/cycling
– Whether from terrestrial ecosystems or
upwellings
The River Continuum Concept
• Energy flows downstream
–
–
–
–
CPOM – course particulate organic matter
FPOM – fine particulate organic matter
UPOM – ultra-fine particulate organic matter
DOM – dissolved organic matter
• Invertebrate Community Groups
–
–
–
–
Shredders – Feed on CPOM
Collectors – Feed on FPOM and UPOM
Grazers – Feed on algae/periphyton growth
Predators – Feed on other invertebrates
1 – 3 order: P/R < 1.0
–Energy rich allochthonous
materials are entering the
system
–Collectors, shredders
4 – 6 order: P/R > 1.0
–More materials are
produced by photosynthesis
than are used by respiration
–Collectors, grazers
> 6 order: P/R < 1.0
–Energy rich allochthonous
materials are entering the
system
–Collectors, predators
What did the fish say when it hit a
brick wall?
Dam!
River Dam(n)s
• Block passage of migratory species
– Anadromous, catadromous
• Reduce stream sediment load
• How can this affect ecosystems?
– (Freeman 2003)
Spawning Migrations
• Salmon and trout bring marine derived
nitrogen (MDN) upriver
• Important for offspring
• Important source of nutrients for many
animals
• How does a decrease in salmon and trout
(and other anadromous fishes)
populations affect ecosystems
– (Willson and Halupka 1995)
Salmon Carcass Replacement Program
• Program places harvested salmon
carcasses in streams
• Could be placing PCB’s and other
pollutants into the ecosystem
– (Missildine 2005)