Annual Carbon Flux (1015 g C⋅yr-1) Annual Carbon Flux (1015 g C⋅yr-1) Annual Carbon Flux (1015 g C⋅yr-1)

1.2

North America

1.2

Europe

1.0

1.0

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.2

0.0

0.0

-0.2 1840 1860 1880 1900 1920 1940 1960 1980 2000

-0.2 1840 1860 1880 1900 1920 1940 1960 1980 2000

1.2

Tropical America

1.2

Tropical Africa

1.0

1.0

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.2

0.0

0.0

-0.2 1840 1860 1880 1900 1920 1940 1960 1980 2000

-0.2 1840 1860 1880 1900 1920 1940 1960 1980 2000

Tropical Asia 1.2 1.0

Total 2.5 2.0

0.8 0.6

1.5

0.4

1.0

0.2 0.0 -0.2 1840 1860 1880 1900 1920 1940 1960 1980 2000

0.5 0.0 1840 1860 1880 1900 1920 1940 1960 1980 2000

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Desertification And Vegetation Feedbacks Overgrazing

Drought

Reduced Vegetation Cover

Less Rainfall

Increased Albedo Decreased Clouds And Convection

Subsidence

Decreased Net Radiation

Surface Cooling

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Cumulative Expansion Of Sahara Desert 300

0.30

Southward Expansion (km)

Normalized Difference Vegetation Index

0.35

0.25 0.20 0.15 0.10 0.05 0.00 0

200

400

600

800

1000

250 200 150 100 50 0 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990

Annual Precipitation (mm)

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

9-13 August 1988, 1100 local time

10 0

Mexico-U.S. Difference (°C)

Mexico-U.S. Difference (W⋅m-2)

Effect Of Overgrazing In The Sonoran Desert On Climate

Latent Heat Sensible Heat

-10 -20 -30 -40 -50 -60 -70 2

3

4

Days Since Rain

5

6

3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5

Air Temperature Surface Temperature

2

3

4

5

6

Days Since Rain

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Present Day Vegetation In The Murray-Darling Basin Circa 1980s Remaining Forest

Brisbane

Forest Woodland Open Woodland

Remaining Woodland

Mallee

Remaining Mallee Other Vegetation Unchanged Some Tree Loss

Area (thousand km2) 64 40 162

Saltbush Grassland Crops Pasture

Brisbane

Pre-European Vegetation In The Murray-Darling Basin Circa 1780s

Area (thousand km2) 58

Greatest Tree Loss

124

349

199

143 Sydney

Adelaide

533 North

Adelaide

Sydney

54 82

324

North Melbourne

Melbourne

500 km

500 km

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Sagebrush 120 Treated 100

Untreated

80 60 40 20 0 -2

0

2

4

6

8

Aboveground Production (g⋅m-2⋅yr-1)

Aboveground Production (g⋅m-2⋅yr-1)

Effect Of Sagebrush Control On Soil Water Grass 120 100 80 60 40 Treated

20

Untreated 0

10 12 14 16 18 20

-2

350 300 250 200 150 100 Treated

50

Untreated

0 -2

0

2

4

6

8

10 12 14 16 18 20

Years After Treatment

2

4

6

8

10 12 14 16 18 20

Years After Treatment Soil Water Depletion - Treated (mm)

Seasonal Soil Water Depletion (mm)

Years After Treatment

0

350

300

250 y=0.61+0.91⋅x 200

150 150

200

250

300

350

Soil Water Depletion - Untreated (mm) Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Drying Of The Aral Sea Annual Inflow

Water Depth

80

55

60

50

50

Meters

Cubic Km Per Year

70

40 30 20

45

40

10 0 1920 1930 1940 1950 1960 1970 1980 1990

35 1920 1930 1940 1950 1960 1970 1980 1990

Surface Area

Volume

70

60 55 50 45 40 1920 1930 1940 1950 1960 1970 1980 1990

Cubic Kilometers

Thousand Square Km

1000 65

800 600 400 200 0 1920 1930 1940 1950 1960 1970 1980 1990

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Micrometeorology Of Pastures And Forests In The Brazilian Amazon 5.0 Pasture Forest

16 14 12 10 8 6 4

4.5 Evapotranspiration (mm)

2

3.5 3.0 2.5 2.0 1.5 1.0 Pasture Forest

0.5 0.0

0 Solar Radiation Incoming (S↓)

Reflected (S↑)

Net Upward Net Longwave Radiation (L↑-L↓) (S↓-S↑+L↓-L↑)

0

5

10

15

20

25

30

Days Since Rainfall 13

Dec

Nov

6

Oct

1800

Sep

1200

7 Aug

0600

8

Jul

0

9

Jun

500

10

May

1000

11

Apr

1500

Pasture Forest

12

Mar

2000

Diurnal Temperature Range (°C)

Pasture Forest

Feb

2500 Boundary Layer Height (m)

4.0

Jan

Radiative Flux (MJ⋅m-2⋅day-1)

18

Local Time (hours) Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Role Of Deep Roots In Tropical Climate Intertropical Convergence Zone Strengthened Circulation Intertropical Convergence Zone More Convection Moister Air

Low Transpiration

Precipitation Increased Transpiration

Increased Precipitation

Wet Soil

Dry Soil

Summer Hemisphere (wet season)

Shallow Roots

Winter Hemisphere (dry season)

Equator

Winter Hemisphere (dry season)

Equator

Increased Soil Water Summer Hemisphere (wet season)

Deep Roots

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Province of Drenthe, the Netherlands

Forested Area (hectares)

35000 30000 25000 20000 15000 10000 5000 0 1800

1850

1900

1950

2000

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Wood of Ename, Flanders 140

Area (hectares)

Forest

100 80 Grassland

60 40

cleared for agriculture

120

20 Arable Land

0 1200 1300 1400 1500 1600 1700 1800 1900

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

300

Area (million acres)

Urban

30

20

10

Area (million acres)

80 Forest Farm

Area (million acres)

Mountain States

Lake States

New England 40

60

40

Forest Farm

20

200

100 Forest Farm Urban

Urban

0

0

0 1840

1880

1920

1960

2000

1840

1880

1920

1960

2000

1920

1940

1960

1980

2000

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Central New England

Tompkins County, New York 100

100

100

75

Forest Area (%)

Forest Area (%)

Massachusetts Petersham

50 Prospect Hill

25

75 51

50 28

25 19

0 1720

1760

1800

1840

1880

1920

1960

0 1720

1760

1800

1840

1880

1920

1960

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

History Of A 0.36 ha Stand In Harvard Forest, 1803 To 1952 Logging Hurricane Gypsy moth

Chestnut blight

Logging Logging Logging Logging

Logging

10

Logging

12

Logging

Basal Area (m2)

14

Hurricane

16

8 6 Logging

4 2 0 1800

1825

1850

1875

1900

1925

1950

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

-0.14 0.00

-0.02

-0.04

-0.06

-0.08

-0.10

-0.12 Jul Aug Sep Oct Nov Dec

Aug Sep Oct Nov Dec

-0.06 Jul

-0.04

Jun

-0.02

Jun

0.00

May

0.02

May

0.04

Apr

0.06

Apr

0.00 Mar

NDVI Crop

Mar

0.20

Feb

0.30

Feb

0.40

Jan

0.50

Clear Sky Surface Albedo

0.60

Jan

Dec

0.70

Surface Albedo Difference (Crop-Forest)

Dec

Nov

Oct

0.00

Nov

Oct

Sep

Aug

Jul

Jun

NDVI Forest

Sep

Aug

Jul

Jun

May

Apr

Mar

Feb

Jan

Normalized Difference Vegetation Index 0.10

May

Apr

Mar

Feb

Jan

NDVI Difference (Crop-Forest)

0.80 0.35

0.30 Albedo Forest Albedo Crop

0.25

0.20

0.15

0.10

0.05

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Annual Carbon Flux (1015 g C⋅yr-1)

Annual United States Carbon Flux: 1700 To 1990 0.4 0.3 0.2 0.1 0.0 -0.1 1700

1750

1800

1850

1900

1950

2000

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

(°C)

Midday Surface Temperature 36

32 34

32 Fort Collins

30

34

38

34

36

Greeley 36

an org M t r Fo

28

30 30

32 30 34 36 32

38 34

38 36

Surface Temperature At 13:00, 1 August To 15 August 1986

38

36 km Contour From 38 To 28 By 2

Ecological Climatology Chapter 13 Copyright G. Bonan 2002

Native Grassland Soils

Soil Organic Carbon Remaining (percent of original)

100 90 80

Nebraska

70 60 Alberta 50 40 0

10

20

30

40

50

60

Length Of Cultivation (years)

Ecological Climatology Chapter 13 Copyright G. Bonan 2002