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

• Tropical

• Temperate

• Subpolar

• Polar

Hot

Cold

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

• 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

General Biome Types

‘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

Cell 3 South

Cold,dry air falls

Moist air rises — rain

Cell 2 South

Cool, dryair falls

Cell 1 South

Moistair rises,cools, andreleasesmoistureas rain

Cell 1 North

Cool, dryair falls

Cell 2 North

Moist air rises — rain

Cell 3 NorthCold, dryair falls

Polar cap

Arctic tundra

60°

30°

0°

30°

60°

Polar cap

Evergreenconiferous forest

Temperate deciduousforest and grassland

DesertTropical deciduous

forest

EquatorTropical rain forest

Tropical deciduous forest

DesertTemperate deciduousforest and grassland

Global air circulation affects local precipitation

A combination of insolation and precipitation determines global biome distribution

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

Net Primary Production of Terrestrial Biomes

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

11

11

22 22

11

11 11

33 22

Stream Order – Strahler MethodStream Order – Strahler Method

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

3 3 = 4Mississippi River is classified as a 10th or 12th order stream.

Headwater stream classification matters

Major Rivers of The World

NameDischarge 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

You will be required to draw a map of the major rivers of the Mississippi River Basin as part of exam 1.

Mississippi River (Main Stem)

Atchafalaya River (Distributary)

Flow

Distributary – A smaller channel that takes water away from the main stem river.

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

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 8,000 8,800 9,600

Average net primary productivity (kcal/m2/yr)

Net Primary Production (measure of available energy)

N

Where Are We?

Barataria

Terrebonne

Ponchartrain

Atchafalaya

Terrestrial Vegetation Growth During Low Water

Nutrients Released During High Water

Simply put:

More Nutrients = More Plants = More Animals

Inundation of the floodplain is the mechanism of energy and nutrient transfer from terrestrial vegetation to the aquatic community.

= Happy Cajuns!!

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

Grand Isle

Port Sulphur

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 Interior Lakes Mainstem

December

June

August

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

0

2

4

6

8

10

12

14

16

GLN GLS INT FL BL SOC

Dis

solv

ed O

xyg

en (

mg

/L)

Open

Plant

Normoxic Hypoxic

Mean Surface Dissolved Oxygen in Open Water and Plants at Each Site

Green

Brown Black

Air-Water Interface

Low DO Water

Atmospheric oxygen diffuses into water

Fish ‘pipe’ at the microsurface layer

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

Detritus Based Food Web.

From Cole 1988, Waveland Press

Terrestrial leaf litter/detritus input during Flood Pulse

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)