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Y2 T1 Biology 228 > Final Lecture > Flashcards

Flashcards in Final Lecture Deck (263):
1

Ecosystem

all the organisms in a given area, along with nonliving(abiotic) factors with which they interact; a biological community and its physical environment.

Ecosystems exist at many spatial scales (e.g., from ponds to the entire biosphere)

2

Ecosystem ecology

examines flow of energy and chemical cycling in habitats, as well as, the effects of natural and human-induced disturbances on ecosystems
(ex: air/water pollution, tree harvesting)

3

Energy flow:

the passage of energy through the components of an ecosystem

4

Chemical Cycling

unlike energy flow, chemical cycling involves the circular(recycling) movement of materials within the ecosystem.

5

a terrarium is an example of a _______ecosystem

closed

6

Pelagic Habitat(P-cycle)

Example of elemental cycling
-cycle of nutrients:

Bacteria--Protists--Zooplankton---Planktivores(fish)---Piscivores(fish)

7

Abiotic Factors

Abiotic Inputs into the ecosystem include:
•Energy (radiant)
•Inorganic substances (CO2, N, O2, minerals)
•Organic substances (e.g., proteins, carbohydrates, humic acids)
•Water
•Energy (radiant) is an overriding factor that affects temperature, moisture, seasons, and photosynthetic energy
Note that temperature and moisture strongly influence the type of organisms present and the productivity of a given system

******organic and inorganic

8

Cyanobacteria

consume much energy yet aren't consumed by very many predators.

9

Familiar forms of energy(4)

Thermal(heat)
Radiant(light)
Kinetic(motion)
Chemical

1)Energy can be converted from one form to another
2)All forms of life depend on these conversions,
For example photosynthesis:
radiant energy ---> chemical energy (e.g., sugars)

10

1st Law of thermodynamics and Ex

Energy is neither created nor destroyed

Energy may be transformed from one form or another, but the total amount of energy remains unchanged in the universe

ex: the Queen Elizabeth coal fired plant converts chemical energy in coal to electrical energy for the city of Saskatoon

11

2nd law of thermodynamics

conversion of energy from one form or another is always accompanied by a reduction in the order of the universe
or
Energy is converted from one form to another some energy becomes unavailable to do work

12

Biotic inputs (2)

1. Organisms that move into an ecosystem (e.g., animal migrations)
2. Influences from adjacent ecosystems For example, upstream ecosystems or downwind ecosystems; ocean currents.

13

Radiant Energy

Radiant Energy
•Majority of radiant energy reaching the planet is converted to heat
Warms Earth & the Atmosphere, and in turn:
1. Drives the hydrologic (water) cycle
2. Generates air currents (winds) and ocean currents
•A small amount of radiant energy reaches photosynthetic organisms where it may be converted to photochemical energy
This photochemical energy is stored in ~170 billion metric tons of organic material produced globally per year

14

What is energy

The capacity to do work
• Energy can only be described and measured by how it affects matter
•Energy is required to move matter in a direction it would not move if left alone
•All organisms require energy from their surroundings in order to stay alive

15

Energy conversion laws(3)

1) Universal laws govern how one form of energy can be converted to another
2) These laws apply equally to living and non-living things
3.) The laws governing energy conversion are called the laws of thermodynamics

16

thermos=

heat

17

dynamis=

power or force

18

Thermodynamics

the study of energy transformations (conversions) that occur in a collection of matter

19

Queen Elizabeth Coal fired plant

is an example of the 1st law of thermodynamics

energy conversion from chemical energy in coal to electrical energy for the City of Saskatoon.

20

entropy(2)

The amount of disorder in a system = Entropy
-Energy lost in conversion

1. Low Entropy-chemical form
2. Vehicle combustion- 25% for movement, 75% lost

Heat can be considered a form of entropy because it represents RANDOM motion of molecules

21

This photochemical energy is stored in ~______ metric tons of organic material produced globally per year

This photochemical energy is stored in ~170 billion metric tons of organic material produced globally per year

22

PAR

photo- synthetically active radiation=
radiant energy is available for use by photosynthetic organisms
-falls between 400 and 700 nm.

23

nm

nanometres

24

Par falls between ___ and ____ nm

400 and 700

25

Autotroph(self feeders)

Autotrophs (self-feeders): an organism that makes its own food , thereby sustaining itself without eating other organisms or their molecules
•Plants, algae and photosynthetic bacteria are autotroph

26

Autotrophs

Autotrophs are the primary producers of the biosphere. They form the food base that sustain all other organisms (heterotrophs) directly or indirectly.

27

Photosynthesis

Photosynthesis: process by which photosynthetic organisms synthesize food molecules from carbon dioxide and water by using light energy.

Note, only ~1% of the PAR that reaches the autotrophs is actually converted to chemical energy (e.g. sugars)

28

Note, only ~__% of the PAR that reaches the autotrophs is actually converted to chemical energy (e.g. sugars)

1

29

Photosynthesis vs Cellular Respiration(in numbers)

Photosynthesis=
6CO(2)+6H(2)O+Energy ---> C(6)H(12)O(6)+ 6O(2)
Carbon Dioxide+Oxygen+Energy=Glucose+Oxygen Gas

Cellular Respiration=
C(6)H(12)O(6)+ 6O(2) ---> 6CO(2) + 6H(2)O + Energy
Glucose+Oxygen Gas=Energy+Oxygen+Carbon Dioxide

30

Primary Production(2)

Primary production: the rate at which photosynthetic organisms (autotrophs) convert solar energy to chemical energy (organic compounds)
-For example, the primary productivity of the biosphere is 170 billion tons of biomass per year

Types of primary production:
1. Gross Primary Production (GPP): total amount of carbon fixed per area per unit time
2. Net Primary Production (NPP): total amount of carbon fixed per area per unit time minus cellular respiration (R) by the autotrophs
- Net primary production is the carbon that is fixed and potentially available for consumers to use (e.g., herbivores).

31

Biomass or Standing Crop

Biomass or standing crop: the amount of living organic material in an ecosystem (or a subcomponent of the ecosystem, e.g., in plants)

32

For example, the primary productivity of the biosphere is ______ tons of biomass per year

170 Billion

33

Units of Measurement: Primary Production

•As above, but for a given unit of time, e.g., g C per m2 per day

34

Units of Measurement: Biomass or Standing Crop

In terrestrial environments: grams dry matter per m2 (g m-2)
In three dimensional environments (e.g., aquatic): grams dry matter per m3 (g m-3)
Or, carbon content may be substituted for dry matter, e.g., g C per m2 or m3

35

NPP

Net Primary Production (NPP): total amount of carbon fixed per area per unit time minus cellular respiration (R) by the autotrophs
Net primary production is the carbon that is fixed and potentially available for consumers to use (e.g., herbivores).

36

GPP

Gross Primary Production (GPP): total amount of carbon fixed per area per unit time

37

primary production(2)

Primary production: the rate at which photosynthetic organisms (autotrophs) convert solar energy to chemical energy (organic compounds)
-For example, the primary productivity of the biosphere is 170 billion tons of biomass per year

Types of primary production:

1. Gross Primary Production (GPP): total amount of carbon fixed per area per unit time
2. Net Primary Production (NPP): total amount of carbon fixed per area per unit time minus cellular respiration (R) by the autotrophs

-Net primary production is the carbon that is fixed and potentially available for consumers to use (e.g., herbivores).

38

Biomass or Standing Crop

Biomass or standing crop: the amount of living organic material in an ecosystem (or a subcomponent of the ecosystem, e.g., in plants)

39

For example, the primary productivity of the biosphere is _____ tons of biomass per year

170 Billion

40

Units of Measurement: Primary Production

Primary production
•As above, but for a given unit of time, e.g., g C per m2 per day

41

Units of Measurement: Biomass or Standing Crop

In terrestrial environments: grams dry matter per m2 (g m-2) In three dimensional environments (e.g., aquatic): grams dry matter per m3 (g m-3) Or, carbon content may be substituted for dry matter, e.g., g C per m2 or m3

42

Most carbon fixation occurs in the ___

open ocean

43

Primary Production in ____ is low

ocean

44

Tropical rain forest has ____ primary production

high

45

Decomposition

releases inorganic compounds

46

Piscovores

eat Planktivores

47

Difficulties with depicting the flow of energy in ecosystems in food chains (5)

Omnivory: organisms often feed on autotrophs and animals(ex:bears). Are they secondary or primary consumers?

. Some animals feed at different trophic levels at different times through their live(ex:fish)

. Matter may pass through an organism more then once. (Ex: feces of an animal eat by another, then second animal is eaten by first again)

. Some plants feed on animals( ex:pitcher plant)

. Many microorganisms make a living autotrophically and heterotrophically(ex: Euglena are capable of engulfing prey and photosynthesiszing simultaneously.

48

Food Web:

a network of interconnecting food chains that create a more realistic but complex overview of the energy transfers.

49

Duck

is a primary and secondary consumer( omnivore)

50

Most complex part of a food web?

Plankton/Detrivory/Algae portion

51

cellulose lygnen

what is some trees and plants that makes them indigestible to many species

52

Assimilation in digestion

transporting/crossing the gut lining into the body

53

egested

faeces

54

Improvement AE

mastification(chewing), digestive enzymes, symbiotic relationships, and the length and shape of gut

55

endotherms: why they can survive

PE****** slide

56

Summary of energy flow within trophic levels with Example

********

57

trophic transfer efficiency

IE x AE x PE = Trophic Transfer efficiency

58

DDT has a ___ efficiency while energy has a ____ efficiency

high, low

59

Factors influencing Algal Growth

1. Warmer water temperatures
2. air content of toxins

60

Once you hit a certain level of Nitrate in the water supply you can see Blue Baby syndrome when it is converted to Nitrite.

Nitrite prevents oxygen from binding by binding with red blood cells

61

Main source of Phosphate is?

weathering of rock

62

Like Nitrogen, phosphorus is often another "____ ____" restricting plant(also, algal and bacterial) production and it a common compound in fertilizers.

limiting nutrient

-Phosphorus is generally a long term limiting factor

63

Phosphorus cycle has reached a point of peak phosphorous and we will remove all of it by ____

2030

64

Saskatoon is the first city to employ Struvite. What is it?

extracting phosphorus from sewage to use for fertilizer

Also helps at sewage plant as to much phosphorus creates a cement like plaque on machinery.

8-10 mg P/L
<1 mg P/L to release in waterways

65

Pit lakes?

Pit lakes are notoriously high in metals and occur when Phosphorus is moved from pit to pit until there are no more pits to move into. Pits are creates from huge rock removal.

66

Contaminants above the Saskatchewan Surface water Quality objectives?

Cobalt
Mol
********** Phosphorus cycle section

67

If a gaseous cycle is present then the cycle is definitely _____ in it's spread.
ex:

global

Sulfur

68

Sulphur in various forms is associated with ___. Generally Sulphur is the layer above of ____.

Coal

69

DMS

Dimethylsulfide:

a major biogenic gas(biological formation) that enters the atmosphere from the ocean.

70

Biogenic Gases

are the ones that can potentially create clouds

71

shredders shred____

algae

72

Notice the _______ of the stream which allows for more sunlight and higher temps. ______ diminishes which allows for greater diversity of habitats.

_____ in the system provides most carbon

openness

Velocity

Algae

73

Notice the _______ of the stream which allows for more sunlight and higher temps. ______ diminishes which allows for greater diversity of habitats.

_____ in the system provides most carbon

openness

Velocity

Algae

74

A lot of FPOM means more prevalence of ______ feeders

filter

75

larger rivers do not depend on _____ nutrients, they actually deposit nutrients on the shore.

shore

76

order >6 can bring about the need for _______ as sandy bottoms do not support many species. Burrowers enjoy this area

specialists

77

_____ level collectors are really specialized for this area

2ND

78

____ of all water flowing to the ocean is now obstructed with dams

2/3

79

When you pools water in a dam, ______ is accelerated and therefore you lose a lot of water

evaporation

80

______ river discharge a big example of water depletion

colorado

81

California losing agricultural land because of loss of water to _____

dessert

82

Water conservation in urban and agricultural areas are the ______ and yet ______ to implement in helping water problems

cheapest, hardest

people don't want to give up watering there lawn

83

Where a dam releases it's water can affect the downstream environment.

Top of dam-

Middle-

Bottom-

Top- Warmer water that may affect wildlife

Middle-

Bottom- Colder

May affect when water can freeze, also affecting the lifecycles of species

84

Human affects: Dams

Floodplains are no longer flooded because of dams which hugely affects species that have adapted for the floods
-Often floodplains(especially in the tropics) are where fish breed
- Deltas disappear when dams are placed because sedimentation gets stuck behind the dam

85

Cottonwoods thrive when ______

flooded

86

Channelization of rivers

for decades we have been straightening out rivers and dredging them to make them deeper

-ecosystems lost because of loss of flow

87

Lentic environments

standing water: lakes and ponds

88

Saline lakes tend to develop when lakes do not...

discharge but remain stagnent

89

3 Most common processes of lake creation

1. Glaciation
2. Fluvial or Riverine- As sediment is moved around by a river, amounts of water can be cut off and develop into a lake
3. Tectonic(less common)- Lake Baikal

90

Pothole=_____ lakes

kettle

91

Deepest freshwater lake in world

Lake Baikal

92

Older lakes have much more _______ in them

biodiversity

93

Know Epilimnion, Metalimnion, and Hypolimnion!

KNOW IT

94

Level at 1% light is

lower limit of Photic zone

95

If benthos is not oxygenated then you have ______

specialists

96

Biodiversity(y axis) vs. disturbance(x-axis)

high disturbance=low biodiversity
climax community= low biodiversity

97

Taiga= ______ forest

boreal

98

Whittaker's Classification

based on annual precipitation versus average temperature

99

Tundra can be though of as a cold _____

desert

100

Is Whittaker's classification a complete diagram?

No, there are always exceptions like soil makeup as a result of fertilizer

101

Poor soils is not a common feature of global plains

True or False?

True, only way to distinguish grassland from desert in Australia

102

Common crop ,_____, is a type of grass

corn

103

_____ and ______ have very similar climate to Canada
_____ even has introduced salmon

Argentina and Chile
Chile

104

____ are a natural function to remove woody plants from plains

fire

105

Short grass prairie gets most of the rain at the ____of the summer

start-June(spring)

106

Tall Grass Prarie

.June, July August get lots of rain, allowing the prarie to grow ____

very little in Manitoba

tall

107

When Europeans arrived they called _______ grass prarie "daisyland" because of the amount of flowers

mixed

108

Most productive Prarie

Tall Grass

109

Burns were amazingly to return the environment to its natural condition


T or F

T

110

______have extra bark in order to insolate internal area from fire damage

___ degrees Celsius == dead

Burrows


60

111

Know terms like NPP

Net primary Production

112

Temperate Grassland has very little ______ yet fairly high ________

biomass-->NPP or productivity

113

Saskatchewan like the North has a lot of Organic _____ stored in the soil.

In the Tundra there is melting occurring which if oxidized will release a load of carbon from peet

Carbon

114

No till processes may allow for cultivation of food without loss of ______

carbon

115

root to shoot ratio's

___ to ____ times more roots then shoots

2, 3

116

Mean annual temp Saskatoon and tree type

2 degrees

117

Mean annual temp La Ronge tree type

0.7 degrees- Boreal Forest or Taiga

118

Boreal Forest covers ____% of Earth's land Surface

11

119

_____ is a great fiber, better for making paper

Cannabis

120

Boreal= zone of ____ _____

little sticks

121

Slow decomposition in boreal means that there is a lot of ______ _______

organic matter

122

Northern Boreal

receives most precipitation compared to north and southern neighbors

123

degrees days are

how many days that are warm enough to allow for growth

124

Saskatchewan dominated by ______.
It is split in two=

Boreal
Boreal(Boreal Shield and Boreal Plain) and Prairie

125

_______love well drained soils

Jack pine

ex: Athabasca plain

126

_______love well drained dry soils

Jack pine(conifer)

ex: Athabasca plain

127

_________ tree's are the R-strategists that repopulate the trees after a fire

Deciduous

128

Root to Shoot or Shoot to Root?

Root to Shoot

129

Boreal acts like a _____ not a _____ of carbon which is a good thing!

Sink not a Source

130

Impact of global warming has allowed Mountain Pine Beetle to expand its range farther north. It likes ________ but will go after ________.

lodgepole pine, Jack Pine

131

________ pine enjoys high elevations and water filled soil

lodgepole

132

______ and ______ pine hybridize in Alberta

lodgepole and jackpine

133

Jackpine is a _____ species

keystone

134

only ___% efficiency in a car

25= high entropy

135

____ in comparison to photosynthesis occurs all day

respiration

136

gpp

total amount of carbon fixed per area per unit time

137

npp

total amount of carbon fixed per area per unit time minus cellular respiration (R) by the autotrophs

138

what main factors influence primary producting in aquatic

1) Intensity and duration of sunlight 2) Temperature 3) Nutrient levels, particularly N, P and Fe in the open ocean

139

what main factors influence primary producting in terrestrial

1) Intensity and duration of sunlight 2) Temperature 3) Moisture or Precipitation 4) Nutrient levels, particularly nitrogen

140

Saskathewan has a ____ growing period

shorter

141

The influence of precipitation and temperature on terrestrial primary production is interrelated

T OR F

T

142

The ______ in plant leaves is where gases are exchanged with the atmosphere

The stomata (plural of stoma) in plant leaves is where gases are exchanged with the atmosphere

143

Loss of water through stomata is called _______

transpiration

144

photorespiration occurs in C_

C3
•Under dry hot weather •Low CO2 and high O2 concentrations in leaf •Calvin cycle uses O2 instead of CO2 and sugars are not produced

145

CAM plant?

CAM plants (Crassulacean acid metabolism), e.g., cacti

146

C__ plants avoid photorespiration by

C4

C4 plants keep stomata closed during dry & hot conditions, and use a special enzyme system to access very low internal concentrations of CO2
Note: Important C4 plants, e.g., Corn, Sugarcane and Sorghum

147

Transpiration is ____ for primary production while Evapotranspiration is _____.

bad, good

•Evapotranspiration rates are a good predictor of primary production.
•Evapotranspiration integrates the effect of temperature and moisture on primary production
In summary: warm temperatures and sufficient water (to meet the needs of transpiration) can result in great rates of primary production.

148

Bioavailability affects the primary production

Yes, many nutrients can occur at high concentrations in ecosystems, but are not bioavailable
• Nutrients may be bound in compounds that cannot be broken down and transported into biota, or they can be bound in complexes that render them inaccessible (e.g., dead organic material).
• The rate at which a nutrient may be mineralized (or become bioavailable) can be the limiting step controlling primary production
• Nutrient concentrations alone are often poor predictors of primary production

149

Potential Limiting nutrients in aquatic

Fresh Versus Marine

Marine: Nitrogen, Phosphorous, Iron and Silica
Fresh: N, P, Si

Nitrogen(Ammonium (NH4), nitrate and nitrite): For protein synthesis in phytoplankton and bacterioplankton

Phosphorus • Phosphate (PO4) is the most important bioavailable form
• For energy transfer (ATP), nucleic acid synthesis and cell membranes in algae and bacteria

Iron • Bioavailable forms: ferrous iron (Fe2+) and iron bound to organic ligands
• Used to fix nitrogen (N2) and other functions in bacteria and algae

Silica • Silicic acid H4SiO4 most important bioavailable form
• Used in the skeleton of diatoms (a major algal group)

150

Nitrogen

Nitrogen(Ammonium (NH4), nitrate and nitrite): For protein synthesis in phytoplankton and bacterioplankton

151

Phosphorous

Phosphorus • Phosphate (PO4) is the most important bioavailable form
• For energy transfer (ATP), nucleic acid synthesis and cell membranes in algae and bacteria

152

IRON

Iron • Bioavailable forms: ferrous iron (Fe2+) and iron bound to organic ligands
• Used to fix nitrogen (N2) and other functions in bacteria and algae

153

Silica

Silica • Silicic acid H4SiO4 most important bioavailable form
• Used in the skeleton of diatoms (a major algal group)

154

NPIS

NEVER PUNCH ICE SCULPTURES
NITROGEN PHOSPHOROUS IRON SILICA

155

Classic Whole Ecosystem Case Study

fertilization of Lake 226 (ELA, Kenora, Ontario) commenced in 1969
Objective: which if any nutrients (C, N & P) were limiting primary production
Lead to the banning of P in detergents and reduction of P inputs from sewage treatment plants in Canada, the U.S. and Europe

156

Lake Winnipeg Algal Blooms caused by

N & P

157

In general, primary production in many lakes is limited by the availability of _ , as illustrated in the correlation between __-concentration and NPP in lakes from around the world

P

158

Areas with ___(small, medium, or high)intensity grazing have the highest primary production

and why?

medium

•Low grazing rates permit nutrients to be locked up in biomass in vegetation, rendering the nutrients unavailable for further plant production.
•However, under moderate grazing nutrients are rapidly released back to the environment (e.g., through egestion, excretion and decomposition) for re-uptake into vegetation, stimulating further plant production.
•However, overgrazing reduces vegetation biomass to such low levels that autotrophs cannot increase biomass in the ecosystem rapidly (low production)
•For example, if plant biomass doubles every week (production), then a field with 200 kg of biomass is going to produce more biomass in a week than a field that had been grazed down to 1 kg of biomass

159

Primary Producer ecosystems: Best, Worst

Tropical rainforest, extreme desert

160

All consumers participate in the breakdown of _______ compounds into ______ compounds

Decomposition releases ______ compounds (e.g., CO2, NH4, PO4, etc) that can be reused by producers (this maintains ecosystem productivity

organic to inorganic

inorganic

161

food web

a network of interconnecting food chains
Food webs provide more detailed information about trophic relationships or “who eats who” and therefore, are more realistic, but complex.
What type of consumer is the duck?

162

secondary production

Secondary production: the rate of accumulation of biomass by heterotrophic or consumer organisms
Secondary production may be expressed in similar units as primary production, e.g., •Terresterial habitats: g C m-2 day-1 •Aquatic habitats: g C m-3 day-1 •Or units of energy may be used, e.g., kJ m-2 day-

163

In general ecosystem with high primary production tend to have _____ secondary production

high

164

3 Fundamental efficiencies of energy transfer

1. Ingestion or consumption efficiency
2. Assimilation efficiency
3. Production efficiency

165

IE for herbivores

_% in forests, __% in grasslands and __% in phytoplankton dominated communities.

5,25,50

166

adaptions of prey(3)

•Prevent easy detection (e.g., cryptic coloration), •Some prey are difficult to subdue (e.g., spines), •And some prey may not be completely consumable (e.g., shell of a turtle).

=lower ingestion efficiency of carnivores

167

Carnivores have a ______ AE

higher

168

The relative ease of assimilating prey is referred to as

food quality

169

predator adaptions to counter bad food quality

in mastication, digestive enzymes, symbiotic relationships, and the length and shape of the gut represent features that can be modified through evolution to improve AE

170

Endotherms use about __% of their assimilated energy in respiration and only __% to secondary production

98
2

171

__x __ x __= trophic transfer efficiency

IE x AE x PE = trophic transfer efficiency

•Energy transfers between trophic levels generally occur with a ~10% trophic transfer efficiency

172

_____ _____ HAS AN INVERTED BIOMASS PYRAMID

OPEN OCEAN= MORE HERBIVORES THEN PP

173

Production of one kg (2.2 lbs) of beef requires:

1) 20,000 litres of water 2) 15 kg of grain 3) 32 kg of topsoil 4) 8 litres of gasoline

174

Solutions for a cultivated planet

• Crops that require less energy, fertilizer/manure and biocides are essential to:
-reduce greenhouse gas emissions -water pollution for fertilizers and biocides
• Better transportation and storage of food is required:
-reduce retail and household waste in developed world -improve transportation and storage in developing world

175

Cold Condensation theory

Many of these POPs are still in use in agricultural settings in the tropics
In the tropics, at warm temperatures, POPs vaporize into the air and are carried thousands of kilometres in air currents
If they reach cold environments, they condense, collect in snow and ice and melt out in spring to eventually enter Arctic food webs

176

Biogeochemical Cycles

processes by which matter cycles from the living world to the nonliving physical environment and back again

177

Carbon Cycle

•Carbon is present as carbon dioxide, carbonate (CO3-2) and bicarbonate (HCO3-)
and
as dissolved organic matter (DOM) in aquatic systems & soil
•Plants and algae remove inorganic carbon (e.g., CO2) from their environment and fix it into organic carbon compounds (e.g., glucose)
•Many of these compounds are used as fuel for cellular respiration by the producers that created them, or by consumers, or by decomposers
•Cellular respiration returns CO2 back to the abiotic environment (e.g., atmosphere or dissolved in water)
•Plants and algae remove inorganic carbon (e.g., CO2) from their environment and fix it into organic carbon compounds (e.g., glucose)
•Large quantities of inorganic carbon are also stored in limestone rock (CaCO3) for millions of years

•Combined with fossil fuels, this represents the largest reservoir
.Most is in ocean

•Photosynthesis and respiration are the two opposing processes that drive the global carbon cycle in the biosphere •Historically the lithosphere played only a minor role; fossil fuels were dormant reservoirs of carbon until humans started mining and burning them.

178

Greenhouse affect?

•CO2 in the atmosphere traps heat and creates the greenhouse effect
•Normally, the greenhouse effect is beneficial because it moderates temperature in the biosphere (our insulation from the cold temperatures of outer space)
•How? Incident radiation is absorbed by the earth’s surface and transmitted back to the atmosphere at longer wavelengths •These longer wavelengths are absorbed by CO2, other greenhouse gases, and water vapour and then converted to heat •This prevents the radiant energy from escaping from the atmosphere back into space

179

3 Major green house gases

Major greenhouse gases: CO2, CH4 and N2O

Carbon Dioxide, Methane, Nitrogen Oxide

180

•Methane is __x more effective than CO2 as a greenhouse gas

Nitrous oxide (N2O) is ___x more effective than CO2 as a greenhouse gas

sources?

20


300

•N2O sources: • fertilizer and manure • industrial (e.g., nylon) • sewage • soil nitrification processes • deforestation

181

•The IPCC now predicts a __ degree rise in average global temperature by 2100

3
•The 20th century saw a 0.7* degree rise
•Many scientists believe we have already undergone a one degree increase

182

British Columbia ______ glaciers are losing _____ cubic metres of water annually

17,000
22 billion

183

Nitrogen Cycle?

•___% of the atmosphere is molecular nitrogen

•Nitrogen is needed to produce many biomolecules (e.g., amino acids, proteins, & nucleic acids)
•All nitrogen found in living organisms has ultimately come from the atmosphere
•The atmosphere is a large reservoir for nitrogen (4 x 109 Mt)
•78% of the atmosphere is molecular nitrogen N2 •However, N2 is very stable and does not readily combine with other elements, e.g., carbon
•Therefore, N2 must be split before it can combine with other elements
•Nitrogen largely enters the ecosystem through microbial fixation, but some also enters through geologic reservoirs.
•Nitrogen leaves ecosystems through denitrification (back to the atmosphere) and through burial and sedimentation

184

5 steps of Nitrogen cycle

1) Nitrogen fixation: the conversion of N2 to NH3 (O2 free environment required)
Certain cyanobacteria and soil bacteria can fix nitrogen with the enzyme nitrogenase (some free living, others in symbiotic relationships with plants)
Wild plants with symbiotic nitrogen fixers are often colonizers of poor soils (e.g., alders). Cultivated legumes have nitrogen fixers
2) Nitrification: the conversion of ammonia (NH3) or ammonium (NH4+) to nitrate (NO3-)
As in the N fixation step, nitrification is also accomplished by a series of bacteria (e.g., Nitrosomonas sp., and Nitrobacter sp.)
3) Assimilation: Plants (via roots), bacteria & algae can absorb NH3, NH4+ NO3- and NO2- and incorporate the nitrogen into organic compounds
These organic N compounds may then move up the food web through consumers
4) Ammonification: the breakdown of organic nitrogen compounds into ammonia (NH3) or ammonium (NH4+)
Decomposers (e.g. bacteria and fungi) are important in the breaking down of nitrogenous waste to ammonium
This ammonium can be recycled back to plants and algae for re-assimilation
This recycling within the food web is a major process in most ecosystems
5) Denitrification: the reduction of nitrate (NO3-) to gaseous nitrogen (N2)
Denitrifying bacteria complete the cycle by converting NO3- to gaseous N2
Requires a low O2 environment

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Human processes with nitrogen?

Human processes now outweigh natural nitrogen

Human processes include: industrial (fertilizer production), fossil fuel, and agricultural fixation (planting of legumes)

186

Cultural eutrophication

•Indirect human fertilization of surface waters is called cultural eutrophication

187

blue baby syndrome

nitrogen is converted to nitrite, binds red blood cells causing anoxia

188

Phosphorous cycle

•Phosphorus is a component in many biomolecules (e.g., ATP), cellular structures (e.g., cell membranes) and morphological structures (bones of vertebrates)
•Phosphate (PO4-3) is the form of phosphorus taken up by organisms from the abiotic environment
•Unlike nitrogen and carbon, phosphorus does not have a gaseous atmospheric phase in the biosphere
•However, it does travel in the atmosphere as dust
•Phosphate comes from the weathering of rock
•The P cycle is less complex than the N cycle
PO4 becomes available to the ecosystems as it is weathered from rock
PO4 is lost from ecosystems when it becomes deeply buried in soils or aquatic sediments

Like nitrogen, phosphorus is often another “limiting nutrient” restricting plant (also, algal and bacterial) production and is a common compound in fertilizers

189

Saskatoon Phosphorous removal

Sewage typically has 10-20 mg P/l
Regulations require P to be at ~1 mg/l before being discharged into the river

190

Bioremediation at DJX pit

•Phosphorus fertilizations resulted in algal growth •P-fertilizations resulted in overall reduced surface water contaminant concentrations •Reduced surface water contaminant concentration was a result of sedimentation of algae to the bottom •The greater the P-load to the mesocosm, the greater the sedimentation of contaminants from the surface waters

191

Sulphur Cycle

•Sulfur is an important element in some amino acids (cysteine & methionine)
•Sulfate (SO4) is the form used by plants, however, many compounds of sulfur are reduced and oxidized by microorganisms (bacteria and algae)
•The S cycle includes gaseous, liquid and solid phases, permitting S to circulate on a global scale
•Largest reservoirs of S are in sedimentary rock, marine sediments, and in the oceans
•S cycle is complex and least understood of the cycles considered

192

Dimethylsulphide

•Dimethylsulfide (DMS) is a major biogenic gas (biological formation) that enters the atmosphere from the ocean
•Created from decomposition of plankton (algae) in ocean surface waters
•DMS is oxidized to sulfate aerosols which are involved in the formation of cloud condensation nuclei (water droplets)
•Clouds have a pronounced effect on climate (cooling effect)
•Therefore, DMS production may provide a partial solution to offset global warming

193

Lotic System

Streams and Rivers
•Steep gradient lotic systems (e.g., alpine systems) are characterized by high velocities (50 cm s-1) and downward erosion into the streambed
•Low gradient lotic systems (e.g., floodplain rivers) are characterized by low velocities and lateral erosion (river banks).
•Low gradient systems may deposit sediment loads eroded from upstream locations

194

Riffles

are zones of fast moving (rapids), shallow, and turbulent water, these are erosional zones, where only moderate to large stones (rubble) may remain without being washed downstream
•Riffles are zones of intense primary production by periphyton (algae growing on rock surfaces)
•These are also zones of great secondary production (aquatic insect larvae)

195

Bottom of streams and rivers is called

benthic zone

196

_______ (~6-25 cm in diameter) provides the best environment for primary & secondary production
(Same)____in fast flowing streams provides the most surface area for algal attachment, and the most crevices for insects to occupy

cobble

197

The wet subsurface sediments make-up the ______

hyporheic zone
•This zone is an ecotone between ground water and stream water
•Water moves in and out (via upwelling and downwelling) of the hyporheic zone resulting in an exchange of nutrients and dissolved organic matter (DOM)
•During low flow conditions invertebrates (e.g. insects) will migrate into the hyporheic sediments

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A small headwater stream without any tributaries is a ____ order stream

FIRST

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Headwater streams are order

orders 1-3
.Considered heterotrophic systems
Large energy and nutrient subsidies enter lotic systems from the terrestrial environment
•High velocity, cold, forested, & shaded
•Shading by riparian vegetation restricts autotrophic production
•90% of organic production comes from input of riparian vegetation (strongly heterotrophic)
•Dominant organisms: shredders that process CPOM and collectors that process FPOM
•Grazers are low in abundance due to little autotrophic (algal) production
Gross primary production to respiration ratio (P/R) is < 1
•Predators include large invertebrates (e.g., stoneflies) and small cold water fish: sculpins, darters and trout
•Organisms of headwater streams are adapted to: • narrow temperature range, • low nutrients, • and maintaining their position in turbulent water

200

Medium Sized Streams are order

4-6
•The importance of riparian vegetation and detrital (leaf) inputs diminishes
•Increased sunshine entering stream (less shading) results in higher water temperatures (solar warming)
•Velocity diminishes & a greater # of habitats are created, and this results in greater biodiversity of organisms
•Fish tolerate higher temperatures and lower O2 concentrations
•More light, higher temperatures and less terrestrial input = switch to autotrophy, P/R >1,
•Algal and macrophyte production is greater
•Little CPOM, so shredders are not as prevalent
•Collectors feeding on FPOM (processed upstream) become dominant
•Grazers become dominant with the increase in algal production
•Predator abundance remains unchanged

201

Rivers are order

>6
•River channel is wider and deeper
•Velocity declines and material is being deposited out of the water column (sandy or silt bottom)
•Influence of riparian inputs decline due to size of river, and autotrophic production also declines due to turbidity, river shifts back to heterotrophy P/R <1
•FPOM is the dominant source of energy used by bottom dwelling collectors (e.g., chironomids)
•River is becoming more lake-like
• Pelagic organisms start to appear
• Phytoplankton
• Zooplankton community
•Encounter warm water fish that tolerate low O2 and consume plankton
Throughout the downstream continuum organisms take advantage of inefficient feeding upstream.

202

heterotrophic system?

heterotrophic systems (ecosystem respiration, R, exceeds primary production, P)

203

riparian(____)

riparian (streamside) vegetation

204

CPOM VS FPOM VS DOM

•Inputs > 1 mm = coarse particulate organic matter (CPOM)
•Inputs < 1 mm = fine particulate organic matter (FPOM), e.g., leaf fragments, insect faeces
•Inputs < 0.5 μm = dissolved organic matter (DOM) e.g., dissolved materials leaching in from the surrounding landscape in groundwater ex: Leaf

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Shredders

•The presence of these microbes on the leaf, render the leaf more nutritional to specialized invertebrate shredders
•The shredders assimilate ~40% of the material that they ingest, the rest is egested as faeces back to the stream as FPOM
•CPOM and FPOM are also produced from physical breakdown of the leaves as they move downstream

206

Collectors

•Invertebrates that specialize in collecting FPOM through filtering and gathering (termed collectors) extract further nutrition from the microbial laden FPOM

207

Scrapers

•Other invertebrates, called scrapers feed on the algae on rock surfaces
•Their scraping activities loosen material off rock surfaces, and what is not ingested contributes to the FPOM pool (travelling downstream)
•Some scrapers have unique adaptations for living in fast water (of the riffle)

208

drift

This downstream benthic material is called drift and subsidizes downstream environments with energy and nutrients

209

Physical Retention

-Physical retention concerns the storage of the nutrient, i.e., in leaf packs or debris dams, or in wood detritus such as logs

refers to the uptake & storage in living organisms

210

longitudinal spiral

Tight versus loose spiral

All these processes (e.g., uptake, transformation & release downstream) are described by lotic ecologists with a

Tight: important for retaining nutrients in fast waters
Possible cause: abundant debris dams

Loose: less retention of nutrients
Possible cause: e.g., flood waters
•The longer the spiral length, the less efficient the system is in retaining nutrients •Physical structure in the stream, e.g., boulders & debris dams, slow the water & create habitat for microbes that will take up nutrients and shorten the spiraling lengt

211

river continuum concept

was a major advance in viewing lotic systems as “longitudinally integrated” ecosystems
•Lotic systems are intimately linked to their drainage basins
•And downstream functioning is strongly tied to processes occurring further upstream
The RCC links stream size, organic matter inputs (energy), the processing of organic matter, and the structuring of invertebrate communities from the headwaters to the mouth of lotic systems
RCC was developed from a synthesis of research on small forested temperate streams of Eastern North America

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Human impacts on lotic system
•_______(fraction)of all water flowing to the ocean is now obstructed with dams

•Two thirds of all water flowing to the ocean is now obstructed with dams
•Most large rivers are dammed except in Canada and Russia
•Majority of dammed water is used for irrigation
•Humans return water to rivers in a polluted form
•Much of dammed water is lost to evaporation

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Upstream Affects of a Dam

•Sediment load in river settles in reservoir & displaces benthic biota •Flooded terrestrial vegetation decomposes and O2 is lost •Anoxia may become prevalent in reservoir •Rise in nutrients & metals & increases in algal production •Anoxia & poor water quality prevail •Some metals are toxic (e.g., mercury) •Migration of biota up & downstream is impeded •organisms cannot migrate and are lost from the upstream system (e.g., salmon)

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Downstream Affects of a Dam

Lake Diefenbaker reservoir, ~__% of useable water evaporates in a typical year

•Reduction in water & loss of habitat •Water evaporates •Water is removed for irrigation and other uses
Lake Diefenbaker reservoir, ~15% of useable water evaporates in a typical year
•Thermal regimes of river water are modified: •Bottom draw from a dam is often colder & has low O2 •Surface draw is often warmer
•Loss of floodplains and associated vegetation and fauna •Without floods, connection between river and surrounding floodplain is reduced
•Disappearance of floodplain deltas (e.g., Nile delta) •Sediments are held behind dams and do not replace eroded sediments downstream in delta


215

• __% of Colorado Rivers' water is used for irrigation

70

216

Cheapest and Most expensive ways to save water

Water conservation and SEAWater Desalination

217

Lake or _____ systems

Lentic
Lakes and ponds: basins in the landscape that collect water (size: < 1 ha to large seas)
Lakes are formed by a variety of processes (over 70 processes)
Major processes include: glacial (74%), fluvial or riverine (10%), and tectonic (5%)
glacial: Glacial Canadian Shield lake,Glacial tarn or cirque lake ,Glacial prairie pothole lakes.

218

3 Worlds biggest collection of Freshwater

•Lake Baikal 20% •Laurentian Great Lakes 20% •Tanganyika 20%

219

Saskatchewan has ______ freshwater lakes

100,000

220

Fluvial lakes

lakes that are alongside rivers that were cutoff in the past

221

Thermal Structure of a lake in summer:3

Thermal Structure of a Deep Lake in Summer
Epilimnion: warm , well mixed, well lit surface water

Metalimnion: region of rapid temperature & density change between warm epilimnetic waters and cold hypolimnetic waters, slow mixing

Hypolimnion: cold, oxygen-poor, dark zone that lies below the metalimnion, zone of little mixing

222

Thermal Structure of Lake over full year:A,B,C,D

A. Winter stratification
•Low density 0C water lies at surface under ice
•Denser 4C water is at bottom
B. Spring turnover
•Ice melts, water completely mixes top to bottom with the help of wind
•Temperature is similar throughout (~4C, isothermal)
C. Summer stratification
•Surface waters warm with increasing solar radiation
•Low density warm surface water sits on the cold dense water below
•Epilimnion, metalimnion and hypolimnion become established
D. Fall overturn
•Surface water cools
•Vertical differences in water density diminish
•Lake proceeds to mix top to bottom with wind events (isothermal temp. pattern)

223

Lentic Systems: Light Gradient

•Photic zone: upper lit waters that extend down to 1% remaining light intensity
•Photosynthesis and respiration occur in the photic zone
•Aphotic zone: dark region below the photic zone, where only respiration occurs

224

Littoral Zone

near shore region (extends out from shore to a depth where only 1% surface light remains on bottom)
•Aquatic rooted plants (macrophytes) are common (cattails, lily pads, reeds, etc.) providing habitat for many organisms •Littoral zone fish (e.g., pike, walleye) and aquatic insects will be present •Bottom of the littoral may contain thick productive algal mats
•Macrophytes and algae extend from the shore to the 1% light level depth (~ where P=R)

225

Pelagic Zone

Plankton: organisms (bacteria to arthropods) that are unable to maintain their position in the water column independent of water currents, unlike fish
Phytoplankton: algae, primary producers (Diatoms, Chrysophytes, Cyanobacteria, Chlorophytes, etc). Most are microscopic
•Zooplankton: feed on phytoplankton, include protists (flagellates & ciliates), & metazoans (rotifers, crustaceans & insects)
•Pelagic fish: feed on zooplankton, include lake trout, perch, white fish, etc.

226

Ecosystem within the Lentic System

Littoral Zone
Pelagic Zone
Benthic Zone

227

Benthic Zone

The benthic region underlying the pelagic is often an anoxic zone with very few invertebrates; however, if the benthic zone is oxic, the invertebrates can become abundant
Ex: Freshwater clam

228

Lake Productivity Levels(3)

As a result of the strong relationship between algal biomass & phosphorus, the trophic status (or productive capacity) of a lake can be classified according to the quantity of phosphorus in a lakes water column
.Input of P from benthic sediments, terrestrial litter & stream inflows

Oligotrophic <10 P CONCENTRATION
Mesotrophic 10-30 P
Eutrophic >30 P

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Marine Ecosystems: 4 depth layers
•Largest ecosystems covering __% of the Earth’s surface
•Contain __% of the Earth’s water
•Pronounced effect on Earth’s climate and weather & biogeochemical cycles

•Largest ecosystems covering 75% of the Earth’s surface
•Contain 97% of the Earth’s water
•Pronounced effect on Earth’s climate and weather & biogeochemical cycles

Epipelagic <200 M
Mesopelagic 200-1000
Bathypelagic 1000-4000
Abyssopelagic 4000-6000

230

Highest rate of production in Marine system

Bacterial production (photosynthetic and heterotrophic)

231

Marine Ecosystem open ocean pp and pc

•Phytoplankton (prokaryotic and eukaryotic are the primary producers in photic zone (top 200 m)
•However, 80% of light energy is absorbed in the first 10 m
•Water column is as bright as a star-lit night at 600 m; majority of the ocean is dark
•Zooplankton (copepods) are the primary consumers
•Both zooplankton and phytoplankton drift with the currents

232

Open Ocean

However, due to their vastness, the oceans account for __% global carbon fixation (or __% of the air we breath comes from the oceans)

However, due to their vastness, the oceans account for 50% global carbon fixation (or 50% of the air we breath comes from the oceans)

•Majority of ocean is N or P limited, and there has been a debate about which nutrient over the long term controls primary production
•This has immediate relevance to the carbon cycle and global warming

233

•Tyrrell (1999) illustrated with a mathematical model that P ultimately controls primary production

WHY? Potential explanation…recall your N and P cycles

•There is an endless supply of gaseous nitrogen (N2) that diffuses into the water
•This N2 can be fixed readily by Cyanobacteria when N03 and NH4 concentrations become limiting in the water column
•When P concentrations become limiting, a gaseous supply of P does not exist
•Therefore, additional forms of P cannot enter the water column and be fixed into biomolecules by phytoplankton, or bacteria.
•Hence, these organisms are restricted in biomass by the amount of P available in the water column (over the long term)

234

Kelp: Growing issues of overuse

•Kelp are brown algae that grow on rocky shorelines
•Kelp forests can reach 60 m heights, and form complex habitat
•Coral reefs & kelp forests have high biodiversity & are very productive
•Corals and kelp exist in low nutrient waters
•High rates of productivity are maintained by rapid recycling and retention of nutrients within the biotic components of the ecosystem
•This is similar to tropical rainforests
•>600,000 tonnes of Kelp are exploited annually for alginate for many uses (e.g., food, thickeners, cosmetics etc)
•Kelp forests are fast growing and over- exploitation is not a problem (yet?)

235

Zooxanthellae photosynthetic dinoflagellates

• Zooxanthellae are photosynthetic dinoflagellates (algae) that form symbiotic relationships with reef forming corals (hard corals)
•Calcification in hard corals is much more rapid when light is present
•Zooxanthellae are photosynthesizing and producing glycerol for the coral
•When corals get “stressed” they lose their zooxanthellae, or zooxanthellae lose their pigments
•This results in the loss of color of many corals and is called coral bleaching
•This may occur from extreme temperatures, lack of sunlight (turbid water), or from acidification of the surrounding water
•The corals may die, but often regain their symbiont within a few months

236

Estuaries

•Estuaries are found where rivers meet the ocean
•Estuarine organisms are posed with two problems: -Maintaining their position as tides and river water moves in the estuary -Adjusting to changing salinity as freshwater dilutes saltwater
•Most estuarine organisms are tolerant of salinity changes
•However, zonation of clams and other benthic organisms does occur down the estuary based on salinity preferences
Structure
•Freshwater floats on saltwater in a seaward direction
•Freshwater sediment & organic matter settles & crosses the pycnocline
•A brackish* bottom water countercurrent carries this nutrient laden material back upstream and creates a sediment trap
•Fertile tidal marshes and mudflats are created

•Estuaries have soft muddy bottoms, unlike the hard substratum of the rocky intertidal
•These muds will be nutrient rich, and support a large biomass of organisms, but biodiversity is relatively low in estuaries
•High nutrient inputs create excess algal production and result in anoxic zones or “dead zones” that are becoming more prevalent globally
•For example, Gulf of Mexico, Gulf of St. Lawrence, Baltic Sea, Black Sea, Chesapeake Bay, all have major “dead zones”

237

grassland definition

land covered with herbaceous plants with <10% tree & shrub cover

238

grasslands
Once covered __% of Earth’s land surface

Once covered 42% of Earth’s land surface
•High rates of evaporation
•Severe droughts on seasonal or multi-year scales
•Prairie soil is among the most fertile worldwide (e.g., 12 x the humus layer of a typical forest soil)
•Rainfall between 250-750 mm y-1 (too light for extensive forest, but too heavy for desert)
•Dominated by grazing and burrowing animals
•Requires periodic fires to be maintained (to remove woody plants)

239

Two grass growth forms of Grasslands

•Sod grasses: develop a solid mat above the soil
•Bunchgrasses: grow in clumps. Other non-grass plants (e.g., forbs) may grow between these clumps
•Roots may reach to a depth >2 m
•Some sod grasses will take on a bunchgrass form under different environmental conditions (e.g. dry soils)
•Most grasses have rhizomes or underground stems for new plant propagation, and food storage

240

Short Grass Prarie

. High moisture June
• Found in Saskatchewan (south west) and Alberta • Kindersely marks its northern distribution
• Associated with the drier sections of the Canadian Prairie
• Annual precipitation below 350 mm:
• Mean annual temperatures below 3oC
• Moisture usually plentiful only in spring
• Very dry summers
•Grasses are typically under 50 cm in height
•Dense sod grasses (few forbs, but some can exist, e.g., asters)
•This region has more “natural” cover than mixed- and tall-grass regions
•Typically used for ranching (too dry for crops, unless irrigated)
•Overgrazing has shifted vegetation to shorter grasses, or to sage brush, or to cacti

241

Mixed Grass Prarie

Bordered by the short-grass region to the south and the aspen parkland region to the north (found in all three plains provinces)
•The mixed-grass region is more humid and experiences lower mean annual temperatures, resulting in less water stress (e.g., due to evaporation)
•Precipitation: 350 to 650 mm annually:
•Mixture of sod and bunch grasses
•Plants may attain heights of 1.5 m
•Taller grasses occupy lowlands, and shorter grasses occupy higher elevations
•Highly variable precipitation results in year to year variation in the type of grass cover:
• Wet years, taller grasses dominate • Dry years, short grasses
•Most of the mixed-grass prairie has been converted to cropland

242

Tall-Grass Prarie

• Most eastern part of the grasslands in Canada • Located in the Red River basin of central Manitoba • Majority of tall-grass prairie is found in the United States
.Annual precipitation: ~500 to ~1000 mm
• Moisture available well into the summer, unlike the shortgrass and mixed grass zones
• Most productive of the three North American Grasslands
• Soil moisture in the Red River basin persists later into the summer
• This promotes the dominance of late maturing tall grasses
• Grasses on well drained sites can reach heights of 2-3 m
• Although restoration efforts are underway, only a few small patches of tallgrass prairie (i.e., <4 km2) remain in southern Manitoba
• Tall-grass prairie is susceptible to tree invasion due to higher rainfall
• Tree establishment results in losses to grassland biodiversity
• Natural fires once every three to ten years would keep tree establishment to a minimum in the tall- grass prairie

243

Temperate Grassland Ecosystems

Temperate Grassland Ecosystems:
•Contain less biomass •Store considerable organic matter •And have moderate rates of net primary production
Grasslands 20 to 55% productivity efficiency
.higher temp negatively affects grasland

244

Carbon Pools in grasslands

•Organic and inorganic carbon stored in grasslands is estimated at 770-880 Pg (Pg = 1015 g) of carbon globally
•This is equal to 20-25% of all carbon stored in terrestrial ecosystems
•However, they release large quantities when cultivated, or tilled
•Tilling breaks up soil and provides better access to decomposers to previously unavailable carbon compounds
•Many grasslands lose up to 50% of carbon stocks in first year of cultivation
•Cultivated grasslands or rangelands can take 50-100 years to regain lost carbon.

245

Factors Affecting Primary Production

•However, unlike forested ecosystems, grassland production is inversely related to temperature
•This is a result of the effect of temperature on water and nutrient availability
1. High temperatures increase evapotranspiration and can result in water stress in grassland plants
Cooler grassland regions in North America have lower water losses due to evapotranspiration and therefore, lower water stress
2. Nutrient mineralization is greater in soils with greater moisture, compared to dry soils
Therefore, nutrients may be more accessible in cooler regions, where more moisture is present in the soil
. Grazing positive affect
. Fire: (burns in the fall, winter and spring are beneficial)

•Grasslands of moderate rainfall have been replaced with arable annual crops of wheat, oats, corn, rye and barley
•Cultivation of drier grasslands is not economical and these have been converted to meat and milk production
•Natural grazers (i.e., bison & pronghorn in North America, and ungulates in Africa) have been replaced with cattle, sheep and goats

246

Approximately, __% of natural grasslands remain in North America
__% have been converted to croplands and another __% have converted to urban areas

Approximately, 9% of natural grasslands remain in North America
71% have been converted to croplands and another 20% have converted to urban areas

247

Boreal Forest(Taiga)

(World’s Largest Terrestrial Biome)
.La Ronge
•Predominantly coniferous forest
•Most of which lies in Canada, Alaska, and Siberia with smaller sections in Europe
•Covers 11% of the Earth’s land surface or 6.7 million km2
•Includes 1/3 of the World’s forested land and 14% of World’s forest biomass
•Boreal may have been more extensive, centuries of harvesting may have reduced size of this biome
•Dominant forest cover in Canada
•Stretches from the Yukon, through south central Canada and the Great Lake States of the USA into maritime region
•Bordered on the North by Tundra and to the south by prairie and temperature deciduous forest in the east
•Associated worldwide with recently deglaciated areas, humid climates, and low evaporation rates
•As a result, region contains many lakes & wetlands
•Fire is the predominant form of disturbance, unlike grasslands, much of the boreal forest still undergoes natural burns
•Often mineral poor soils that are thin and acidic (especially those directly on the granitic Precambrian Shield )
•But yields vast quantities of lumber and pulp (for paper products)
•World’s primary source of industrial wood and wood fibre

248

Boreal Forest Climate

•However, outside of coastal regions, the climate is generally continental (i.e., cold winters and hot summers with moderate rainfall ~400 to 700 mm)
•Siberia has the most continental of climates (e.g., a range of 100 degrees celsius in a single year has been noted, -70 to +30oC)
•The unifying criterion is that the prevailing climate promotes conifers over broadleaf deciduous trees.
•Soil decomposition is slow (low temperatures) and leads to the accumulation of peatlands
Most northerly and southerly parts of boreal have lower annual precipitation
Range in Precipitation & Degree Days • Range in Mean annual precipitation ~250 to 450 mm
• Cool temperatures keep the moisture balance high
• Some permafrost is present in extremely northerly sections of Boreal
•Hardwoods (deciduous trees) are sensitive to low winter temperatures and short growing seasons
•Softwoods or conifers are adapted to cold winters and short growing seasons
•Four coniferous genera dominate worldwide • Spruce (Picea), e.g. black spruce • Fir (Abies), e.g., balsam fir • Pine (Pinus), e.g. jack pine • and larch (Larix), e.g., tamarack

249

4 Dominant species of coniferous trees in boreal

•Four coniferous genera dominate worldwide
• Spruce (Picea), e.g. black spruce
• Fir (Abies), e.g., balsam fir
• Pine (Pinus), e.g. jack pine
•and larch (Larix), e.g., tamarack

250

Boreal divided into two in Saskatchewan

Boreal Shield and Boreal Plain

251

Athabasca Plain

located in boreal shield
.Jack pine dominate
Soils are very dry due to good drainage (through sand), this creates pine meadows instead of dense forests (insufficient water to support dense forests)
Soils are also very infertile
A variety of endemic plants exist in this dune area
In deeper soils, deciduous trees may be more prevalent such as white birch and aspens
Lowlands contain lakes or peatlands

Southern Boreal Plain:
•Increase in broadleaf (deciduous) trees and forest productivity from north to south
•Trees reach heights of 25 or 30 m in south
•Greater diversity of vegetation
WHY?
•Longer & warmer growing season
•Soils are more fertile
Note
•Southern boreal across Canada is the main commercial forest region
•Timber harvesting in some regions replaces fire as the main disturbance
•Coarse textured and dry soils favour jack pine (coarse sands)
•Wet soils with low nutrients favour black spruce
•In south, spruce only dominate in peatlands
•In the most southerly region (Boreal Transition Zone), the vegetation becomes more like Aspen Parkland
•Here, conifers are still present, but at decreasing abundance, and pure aspen stands are common
•Some of this observed decline may also be associated with logging in earlier times (conifers have not re-established)

252

Southern Succesional plan saskatchewan

•Aspen can quickly regenerate after a burn and dominate the landscape for decades
•Aspens have a thin canopy, and the extra light that passes to the forest floor permits a lush ground cover of shrubs and herbs
•Spruce slowly develop in underbrush
•In 80 to 100 years aspen die-off, and longer lived spruce push up through the canopy and eventually dominate

253

The Boreal Ecosystem-Atmosphere Study (BOREAS)

to investigate large scale vegetation- atmosphere interactions
•~40% of NPP occurs below ground (compare with grasslands > 50%
•According to BOREAS study the Boreal forest is still a sink for carbon
The turnover* of soil organic matter and nutrients in the Boreal forest is very slow compared to other ecosystems
This is likely a function of the short growing season, cooler temperatures and the type of organic material (recalcitrant to breakdown)

254

Orca's in the North

seem to be expanding there reach into the north
. disappearance of ice allowing them in farther
.traditional knowledge needed from hunters and elders
.marine mammals the prey
.small groups of whales coordinate like wolves in packs hunting narwhales

255

Woody shrubs podcast creeping in on tallgrass prairie

Flint Hills region-where remaining tall grass prairie is
. Maintained by disturbance

256

limnetic

open water

257

eutrophic versus oligotrophic

high nutrient rich lake versus nutrient poor lakes

258

Dystrophic lakes

receive high ammounts of human organic matter

259

gougers

invertebrates that burrow into water logged limbs

260

Anadromous Fish

live most of their lives in salt water, returning to spawn in frwsh

261

2 main divisions of body of water

pelagic zone and benthic

262

benthic is:
benthos:

benthic refers to the floor of the sea
benthos refers to the organisms that live there

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Mean annual temperature determines
Mean Annual percipitation

species composition(tropical,temperate, boreal)
growth form(trees,shrubs,forbs)