1. Biomass in Stems vs Leaves

5. OakNorthern PineSpruce 27 24 21 18 15 12 9 6 3 0 500100015002000500 1000 1500 2000 Annual Precipitation (mm) July Temperature ( o C) 30 40 0 10 30 20 0 10 20 30 20 10 30 0 10 20 30 40 20 10 30 0 0 10 0 Figure 20.2 Ecological Climatology © 2008 G. Bonan

6. 6001000140018002200 Annual Precipitation (mm) 3 5 7 9 11 13 15 17 Annual Mean Temperature (  C) 0.01 0.1 0.7 0.8 0.1 0.01 Probability Of Occurrence Figure 20.3 Ecological Climatology © 2008 G. Bonan

7. Shade Tolerance HighLow Drought Tolerance High Low 12345 6789 101112 13 14 15 Shade Tolerance HighLow Drought Tolerance High Low Decreasing Maximum Growth Rate Biomass Low High Soil Moisture Wet Dry 1 6 10 13 15 Biomass Low High Soil Moisture Wet Dry 1 6 10 13 15 Figure 20.4 Ecological Climatology © 2008 G. Bonan

8. 0 5 10 15 20 25 01-Oct-6331-Oct-6330-Nov-63 30-Dec-63 29-Jan-64 28-Feb-6429-Mar-64 28-Apr-64 28-May-64 27-Jun-64 27-Jul-64 Number Of Main Roots Wheatgrass Cheatgrass 0 5 10 15 20 25 30 35 40 SparseModerateDense Density Of Cheatgrass Number Of Survivors (per m 2 ) Height (cm) Density - June Density - October Height - June 0 5 10 15 20 25 30 35 40 0 20 40 60 80 100 Maximum Root Length (cm) Wheatgrass 273 Cheatgrass Wheatgrass 49 224 Cheatgrass Wheatgrass 136 Cheatgrass Wheatgrass 224 49 Cheatgrass 273 Number Of Plants Figure 20.5 Ecological Climatology © 2008 G. Bonan

9. 051015202530 Field B Field C Litter C:N Ratio 10 20 30 40 50 60 Nitrogen Addition (g m -2 yr -1 ) 051015202530 0 5 10 15 20 30 25 Net Carbon Storage (g C g N -1 ) Fields B, C Nitrogen Addition (g m -2 yr -1 ) 051015202530 Field B Field C 0 10 20 30 40 50 60 70 80 C 4 Biomass (%) Nitrogen Addition (g m -2 yr -1 ) 051015202530 Field B Field C Species Richness 10 0 5 15 20 Nitrogen Addition (g m -2 yr -1 ) Figure 20.6 Ecological Climatology © 2008 G. Bonan

10. 0 20 40 60 80 40060080010001200140016001800 Elevation (m) Percent Of Stand American beech 0 5 10 15 20 25 30 40060080010001200140016001800 Elevation (m) Percent Of Stand Yellow poplarYellow birchMountain silverbell Sugar mapleWhite basswoodYellow buckeye Figure 20.7 Ecological Climatology © 2008 G. Bonan

11. Figure 20.8 0 20 40 60 80 40060080010001200140016001800 Elevation (m) Percent Of Stand Blackjack oakVirginia pine Pitch pine Scarlet oak Table mountain pine Chestnut oak Ecological Climatology © 2008 G. Bonan

12. F B SF ROC CF P OH ROC OCF OCH P B, beech forest Xeric Dry Moderately dry Mesic Cold Moderately wet CF, cove forest F, Fraser fir forest HB GB OCH, chestnut oak-chestnut (dead) heath OH, oak-hickory forest P, pine forest and heath ROC, red oak-chestnut (dead) forest SF, spruce-fir forest OCF, chestnut oak-chestnut (dead) forest GB, grassy bald HB, heath bald H, hemlock forest OCH H H H OH SF 1981 m (6500 ft) 1676 m (5500 ft) Figure 20.9 Ecological Climatology © 2008 G. Bonan

13. 1 10 100 05101520 Species Rank Percent Of Stand Beech forest Cove forest Yellow buckeye Beech Mountain silverbell White basswood Sugar maple Yellow birch Hemlock Yellow buckeye Sweet birch Yellow birch Mtn silverbell White ash Striped maple Red maple Chestnut (dead) Figure 20.10 Ecological Climatology © 2008 G. Bonan

14. Red Oak- Pignut Hickory Forest White Basswood Pitch Pine Heath 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Virginia Pine Forest Table Mountain Pine Heath Grassy Bald White Oak- Chestnut Forest Chestnut Oak- Chestnut Heath Chestnut Oak- Chestnut Forest Red Oak- Pignut Hickory Forest Cove Forests Hemlock Forest Beech Forest Mesic Type Sedge Type CovesFlatsDrawsSheltered Slopes Open SlopesRidges And Peaks CanyonsRavines MesicXeric Elevation (feet) Heath Bald Red Oak-Chestnut Forest 20 10 1 Chestnut Oak Pitch Pine Heath Virginia Pine Forest Table Mountain Pine Heath Grassy Bald White Oak- Chestnut Forest Chestnut Oak- Chestnut Heath Chestnut Oak- Chestnut Forest Red Oak- Pignut Hickory Forest Cove Forests Hemlock Forest Beech Forest Mesic Type Sedge Type CovesFlatsDrawsSheltered Slopes Open SlopesRidges And Peaks CanyonsRavines 457 610 762 914 1067 1219 1372 1524 1676 1829 1981 MesicXeric Elevation (meters) Heath Bald Red Oak- Chestnut Forest 1 5 5 1 10 20 10 Eastern Hemlock Pitch Pine Heath 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Virginia Pine Forest Table Mountain Pine Heath Grassy Bald White Oak- Chestnut Forest Chestnut Oak- Chestnut Heath Hemlock Forest Beech Forest Sedge Type CovesFlatsDrawsSheltered Slopes Open SlopesRidges And Peaks CanyonsRavines MesicXeric Elevation (feet) Heath Bald Red Oak-Chestnut Forest 0.5 1 1 10 20 Pitch Pine Heath Virginia Pine Forest Table Mountain Pine Heath Grassy Bald White Oak- Chestnut Forest Chestnut Oak- Chestnut Heath Chestnut Oak- Chestnut Forest Red Oak- Pignut Hickory Forest Cove Forests Hemlock Forest Beech Forest Mesic Type Sedge Type CovesFlatsDrawsSheltered Slopes Open SlopesRidges And Peaks CanyonsRavines 457 610 762 914 1067 1219 1372 1524 1676 1829 1981 MesicXeric Elevation (meters) Heath Bald Red Oak-Chestnut Forest Red Maple 10 5 5 20 10 5 50 1 Chestnut Oak- Chestnut Forest Cove Forests Mesic Type Figure 20.11 Ecological Climatology © 2008 G. Bonan

15. Soil Water Temperature Soil Water Biological Performance (abundance, growth, survival) Temperature Soil Water Light Low High 100% 75% 50% 25% 0 % Growth Figure 20.1 Ecological Climatology © 2008 G. Bonan

16. 2826 3856 Foliage and fruit 332 9094 Root Branch Stem Total Living: 16 108 g m -2 Biomass 322 266 254 160 Net Primary Production: 1002 g m -2 yr -1 Net Ecosystem Production: 322 g m -2 yr -1 680Decomposition Root Branch Stem Foliage and fruit Production And Decomposition Sugar maple 35% Beech 27% Yellow birch 23% Paper birch 5% Red spruce 4% Balsam fir 3% Pin cherry 2% Striped maple 1% Density: 549 trees per ha (> 10 cm DBH) DBH > 10 cm 0 50 100 150 200 250 300 Low (546-625 m) Middle (625-709 m) Upper (709-791 m) Density (per ha) Sugar mapleBeechYellow birch Figure 21.1 Ecological Climatology © 2008 G. Bonan

17. Leaf Stem Root Leaf Stem Root Tree Shrub Consumers Litter Decomposers Humus GrazingLitterfall Gross Primary Production Autotrophic Respiration Heterotrophic Respiration Figure 21.2 Ecological Climatology © 2008 G. Bonan

18. 1456 675 505 Understory 51 616968 Foliage 94 897 3599 1943 Standing dead Mineral soil Forest floor Understory 72 Stem 8271 Branch Total Living: 9334 g C m -2 Total Detritus: 6510 g C m -2 Total Ecosystem: 15 844 g C m -2 Mineral soil 39 036 Standing dead Moss 60 Stem 3633 Branch Foliage Total Living: 4924 g C m -2 Total Detritus: 39 652 g C m -2 Total Ecosystem: 44 576 g C m -2 Mineral soil Forest floor Standing dead567 1420 Lichen 347 Understory 16 2576 Stem 413Branch Foliage 103 Total Living: 3455 g Cm -2 Total Detritus: 3443 g C m -2 Total Ecosystem: 6898 g C m -2 Quaking AspenBlack SpruceJack Pine Age: 67 years Height: 20 m Density: 980 ha -1 Mean diameter: 20 cm LAI: 3.3 m 2 m -2 Age: 115 years Height: 7 m Density: 5900 ha -1 Mean diameter: 7 cm LAI: 5.6 m 2 m -2 Age: 65 years Height: 13 m Density: 1190 ha -1 Mean diameter: 13 cm LAI: 2.4 m 2 m -2 Stand Structure Living Biomass Detritus Figure 21.3 Ecological Climatology © 2008 G. Bonan

19. 0 500 1000 1500 2000 2500 0500100015002000 Elevation (meters) Tree Production (g m -2 yr -1 ) 700 800 900 1000 1100 1200 Low (546-625 m) Middle (625-709 m) Upper (709-791 m) Figure 21.4 Ecological Climatology © 2008 G. Bonan

20. 800 1000 1200 1400 1600 1800 198419851986 Aboveground Net Primary Production (g m -2 yr -1 ) Pre-TreatmentTreated Figure 21.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0510152025 Stem Diameter (cm) New Foliage (kg) Untreated Irrigated Fertilized Ecological Climatology © 2008 G. Bonan

21. Total Tree And Understory Forest Floor And Soil 05101520253035 Stand Age (years) 0 35 000 5000 10 000 15 000 20 000 25 000 30 000 Biomass (g m -2 ) 0 1 2 3 4 5 6 7 05101520253035 Stand Age (years) Leaf Area Index (m 2 m -2 ) 0 200 400 600 800 1000 1200 1400 Aboveground NPP (g m -2 yr -1 ) LAI NPP Figure 21.6 Ecological Climatology © 2008 G. Bonan

22. 352 g C m -2 yr -1 Wood 50% Wood 7% Foliage 21% Understory 15% Understory 7% 166 g C m -2 yr -1 Wood 48% Wood 7% Foliage 5% Foliage 25% Understory 8% Moss 7% 117 g C m -2 yr -1 Wood 51% Wood 11% Foliage 2% Foliage 32% Understory 4% 392 g C m -2 yr -1 Aboveground 90% Belowground 10% 286 g C m -2 yr -1 Aboveground 58% Belowground 42% 222 g C m -2 yr -1 Aboveground 53% Belowground 47% Quaking Aspen Total NPP Aboveground NPP Black Spruce Jack Pine Figure 21.7 Ecological Climatology © 2008 G. Bonan

23. 6 8 10 12 Precipitation (mm) Temperature (  C) P T 0 1000 2000 3000 6 8 10 12 Precipitation (mm) Temperature (  C) PT 0 1000 2000 3000 6 8 10 12 Precipitation (mm) Temperature (  C) PT 0 1000 2000 3000 6 8 10 12 Precipitation (mm) Temperature (  C) PT 0 1000 2000 3000 6 8 10 12 Precipitation (mm) Temperature (  C) PT 0 1000 2000 3000 Precipitation (mm) 6 8 10 12 Temperature (  C) PT 0 1000 2000 3000 0 10 20 30 40 50 Height (m) 0 10 20 30 40 50 Height (m) 0 10 20 30 40 50 Height (m) 0 10 20 30 40 50 Height (m) 0 10 20 30 40 50 Height (m) 0 10 20 30 40 50 Height (m) 121.0121.5122.0122.5123.0123.5124.0 Longitude (  W) 0 200 400 600 800 1000 1200 1400 1600 1800 2000 0255075100125150175200225 Elevation (meters) Distance (km) Old growth Sitka spruce and Western hemlock Biomass: 71.1 kg m -2 LAI: 6.4 Juniper woodland Biomass: 1.1 kg m -2 LAI: 0.4 Ponderosa pine Biomass: 1.5 kg m -2 LAI: 0.9 Mountain hemlock Biomass: 37.0 kg m -2 LAI: 1.9 Douglas fir and Western hemlock Biomass: 40.8 kg m -2 LAI: 8.6 Douglas fir Biomass: 47.1 kg m -2 LAI: 5.3 0 500 1000 1500 2000 2500 0 500 1000 1500 2000 2500 Carbon Allocation (g C m -2 yr -1 ) 879 g C m -2 yr -1 1400 g C m -2 yr -1 0 500 1000 1500 2000 2500 1665 g C m -2 yr -1 0 500 1000 1500 2000 2500 2404 g C m -2 yr -1 0 500 1000 1500 2000 2500 0 500 1000 1500 2000 2500 Growth Respiration Maintenance Respiration (Foliage) Maintenance Respiration (Sapwood) Aboveground NPP Belowground Allocation 364 g C m -2 yr -1 302 g C m -2 yr -1 Figure 21.8 Ecological Climatology © 2008 G. Bonan

24. Hydrologic Export 0.40 g m -2 yr -1 Throughfall Stemflow 0.27 g m -2 yr -1 0.66 g m -2 yr -1 Root Litter 0.62 g m -2 yr -1 Root Litter 0.32 g m -2 yr -1 Aboveground Biomass Pool: 38.3 g m -2 Gain: 0.54 g m -2 yr -1 Translocation 0.51 g m -2 yr -1 Throughfall Stemflow 0.67 g m -2 yr -1 Litterfall 4.07 g m -2 yr -1 Belowground Biomass Pool: 10.1 g m -2 Gain: 0.27 g m -2 yr -1 Forest Floor Pool: 37.2 g m -2 Gain: 0.14 g m -2 yr -1 Precipitation 0.22 g m -2 yr -1 Soil Available 51.0 g m -2 Mineral Soil: 960 g m -2 Rock: 6460 g m -2 Weathering 2.11 g m -2 yr -1 Mineralization 4.24 g m -2 yr -1 Root Exudate 0.35 g m -2 yr -1 Vegetation Uptake 6.22 g m -2 yr -1 Hydrologic Export 1.39 g m -2 yr -1 Organically-bound Ca Inorganic Ca Aboveground Biomass Pool: 35.1 g m -2 Gain: 0.48 g m -2 yr -1 Translocation 3.98 g m -2 yr -1 Litterfall 5.42 g m -2 yr -1 Belowground Biomass Pool: 18.1 g m -2 Gain: 0.42 g m -2 yr -1 Forest Floor Pool: 125.6 g m -2 Gain: 0.77 g m -2 yr -1 Precipitation 0.65 g m -2 yr -1 Soil Available Mineralization 6.97 g m -2 yr -1 Root Exudate 0.01 g m -2 yr -1 0.08 g m -2 yr -1 Vegetation Uptake 7.96 g m -2 yr -1 Denitrification ? Organic N Inorganic N CalciumNitrogen N Fixation 1.42 g m -2 yr -1 Figure 21.9 Ecological Climatology © 2008 G. Bonan

25. Foliage 350 3570 13 560 Stump 1170 Branch Bole Total Biomass: 18 640 g m -2 Yellow Poplar 11 910 3140 Stump 1040 Foliage 340 Branch Bole Total Biomass: 16 380 g m -2 Oak-Hickory Foliage 420 3770 14 380 Stump 1220 Branch Bole Total Biomass: 19 770 g m -2 Chestnut Oak Figure 21.10 Ecological Climatology © 2008 G. Bonan

26. Litterfall 4.5 g m -2 yr -1 Foliage Pool: 5.8 g m -2 Branch and Bole Pool: 88.7 g m -2 Gain: 2.5 g m -2 yr -1 Vegetation Uptake 8.2 g m -2 yr -1 Translocation 0.1 g m -2 yr -1 Throughfall Stemflow 1.2 g m -2 yr -1 Mortality 0.3 g m -2 yr -1 Forest Floor Pool: 31.8 g m -2 Litterfall 5.8 g m -2 yr -1 Foliage Pool: 7.5 g m -2 Branch and Bole Pool: 51.7 g m -2 Gain: 1.1 g m -2 yr -1 Vegetation Uptake 8.1 g m -2 yr -1 Translocation 0.5 g m -2 yr -1 Throughfall Stemflow 1.2 g m -2 yr -1 Mortality 0.4 g m -2 yr -1 Forest Floor Pool: 29.4 g m -2 Litterfall 4.9 g m -2 yr -1 Foliage Pool: 7.0 g m -2 Branch and Bole Pool: 87.4 g m -2 Gain: 2.8 g m -2 yr -1 Vegetation Uptake 9.2 g m -2 yr -1 Translocation 0.6 g m -2 yr -1 Throughfall Stemflow 1.5 g m -2 yr -1 Mortality 0.7 g m -2 yr -1 Forest Floor Pool: 41.7 g m -2 Chestnut Oak Yellow PoplarOak-Hickory Litterfall 3.4 g m -2 yr -1 Foliage Pool: 7.5 g m -2 Branch and Bole Pool: 35.6 g m -2 Gain: 2.5 g m -2 yr -1 Vegetation Uptake 6.2 g m -2 yr -1 Translocation 3.8 g m -2 yr -1 Throughfall Stemflow 0.3 g m -2 yr -1 Mortality 0.1 g m -2 yr -1 Forest Floor Pool: 29.8 g m -2 Litterfall 3.6 g m -2 yr -1 Foliage Pool: 7.8 g m -2 Branch and Bole Pool: 18.9 g m -2 Gain: 2.5 g m -2 yr -1 Vegetation Uptake 6.4 g m -2 yr -1 Translocation 3.9 g m -2 yr -1 Throughfall Stemflow 0.3 g m -2 yr -1 Mortality 0.2 g m -2 yr -1 Forest Floor Pool: 18.7 g m -2 Litterfall 3.7 g m -2 yr -1 Foliage Pool: 6.7 g m -2 Branch and Bole Pool: 33.2 g m -2 Gain: 2.6 g m -2 yr -1 Vegetation Uptake 6.7 g m -2 yr -1 Translocation 2.6 g m -2 yr -1 Throughfall Stemflow 0.4 g m -2 yr -1 Mortality 0.3 g m -2 yr -1 Forest Floor Pool: 33.4 g m -2 Calcium Nitrogen Precipitation 1.3 g m -2 yr -1 Precipitation 1.3 g m -2 yr -1 Precipitation 1.3 g m -2 yr -1 Figure 21.11 Ecological Climatology © 2008 G. Bonan

27. High Net Primary Production High Foliage Nitrogen Concentration High Nitrogen Uptake High Nitrogen Availability High Mineralization Rate High Nitrogen Return In Litter Low Net Primary Production Low Foliage Nitrogen Concentration Low Nitrogen Uptake Low Nitrogen Availability Low Mineralization Rate Low Nitrogen Return In Litter Figure 21.12 Ecological Climatology © 2008 G. Bonan

28. 400 500 600 700 800 900 1000 23456789 Nitrogen Mineralization (g N m -2 yr -1 ) Aboveground Net Primary Production (g m -2 yr -1 ) Red Pine Hemlock White Pine Red Oak White Oak Sugar Maple Sugar Maple 0 1 2 3 4 5 23456789 Nitrogen Mineralization (g N m -2 yr -1 ) N Return In Litter (g N m -2 yr -1 ) Red Pine Hemlock White Pine Red Oak White Oak Sugar Maple Sugar Maple 0 0.1 0.2 0.3 0.4 0.5 23456789 Nitrogen Mineralization (g N m -2 yr -1 ) P Return In Litter (g P m -2 yr -1 ) Sugar Maple Red Pine Hemlock White Pine Red Oak White Oak Sugar Maple 0 1 2 3 4 5 6 7 8 9 303540455055606570 Carbon:Nitrogen Ratio Nitrogen Mineralization (g N m -2 yr -1 ) Red Pine Sugar Maple Sugar Maple Hemlock White Pine White Oak Red Oak Figure 21.13 Ecological Climatology © 2008 G. Bonan

29. Figure 21.14 Ecological Climatology © 2008 G. Bonan

30. 269 1519 16 801 g m -2 1248 1636 13 917 7426 5800 9357 1630 234 11 221 g m -2 10 248 12 309 g m -2 286 1775 4750 2200 10 319 12 107 g m -2 197 36 133 366 g m -2 yr -1 155 562 g m -2 yr -1 286 36 240 156 389 227 57 269 553 g m -2 yr -1 469 g m -2 yr -1 251 209 26 234 28.2 g N m -2 15.7 (0.17%) 7.3 (0.45%) 5.2 (2.22%) 86 (1.48%) 26.6 g N m -2 5.9 (2.06%) 5.7 (0.32%) 15.0 (0.15%) 69 (1.45%) 15.6 (0.15%) 6.1 (0.40%) 4.6 (1.71%) 26.3 g N m -2 27 (1.23%) 10.0 (0.07%) 8.9 (0.54%) 8.5 (0.68%) 27.4 g N m -2 57 (0.77%) 3.2 (0.41%) 4.0 (0.72%) 5.1 (0.14%) 12.3 g N m -2 63 (0.82%) Foliage Branch Trunk Forest Floor 0.16 0.26 1.14 1.56 g N m -2 yr -1 0.93 6.54 g N m -2 yr -1 5.9 0.36 0.28 1.48 3.31 0.24 0.56 4.6 5.4 g N m -2 yr -1 5.81 g N m -2 yr -1 1.89 0.25 0.36 5.2 Forest Floor Trunk Branch Foliage 559 788 3643 4990 g m -2 7650 Branch7 33Foliage Trunk Litterfall 70 43 110 g m -2 yr -1 Branch0.07 0.32Foliage Trunk Litterfall 0.14 0.30 0.53 g N m -2 yr -1 Black Spruce White Spruce Paper Birch Quaking Aspen Balsam Poplar BiomassNitrogenNPPN Uptake Figure 21.15 Ecological Climatology © 2008 G. Bonan

31. 0 5 10 15 20 25 30 35 40 05001000150020002500 Soil Degree-Days Forest Floor Thickness (cm) Black Spruce White Spruce Paper Birch Balsam Poplar Quaking Aspen 0 1 2 3 4 5 6 7 5075100125150 Forest Floor Biomass/Forest Floor N N Requirement (g m -2 yr -1 ) 0 100 200 300 400 500 600 700 800 01234567 N Mineralization (g m -2 yr -1 ) Tree Production (g m -2 yr -1 ) 0 2 4 6 8 10 12 14 16 18 500750100012501500 Soil Degree-Days Annual Decomposition (%) 100 110 120 130 140 150 160 170 5075100125150 Forest Floor Biomass/Forest Floor N Litterfall Biomass/Litterfall N 0 100 200 300 400 500 600 700 800 60080010001200140016001800 Soil Degree-Days Tree Production (g m -2 yr -1 ) Figure 21.16 Ecological Climatology © 2008 G. Bonan

32. -8 -6 -4 -2 0 2 4 6 8 19921993199419951996199719981999 Net Ecosystem Production (g C m -2 day -1 ) Uptake Release Figure 21.17 -15 -10 -5 0 5 10 15 19921999199419961998199319951997 GPP Respiration Carbon Flux (g C m -2 day -1 ) Uptake Release Ecological Climatology © 2008 G. Bonan

33. 700 800 900 1000 1100 1200 1300 19921993199419951996199719981999 Gross Primary Production, Ecosystem Respiration (g C m -2 yr -1 ) -300 -250 -200 -150 -100 -50 0 Net Ecosystem Production (g C m -2 yr -1 ) GPP R NEP Figure 21.18 Ecological Climatology © 2008 G. Bonan

34. 0 20 40 60 80 100 120 Cumulative NEP (g C m -2 ) -15 -10 -5 0 5 10 15 Carbon Flux (g C m -2 day -1 ) 1994199519961997 1994199519961997 Release -2.5 -2.0 -1.5 -0.5 0.0 0.5 1.0 1.5 2.0 Net Ecosystem Production (g C m -2 day -1 ) 1994199519961997 Uptake Release Uptake Release Figure 21.19 Respiration GPP Ecological Climatology © 2008 G. Bonan

35. 500 550 600 650 700 750 800 850 900 950 1995199619971998199920002001200220032004 -80 -60 -40 -20 0 20 40 60 80 100 Net Ecosystem Production (g C m -2 yr -1 ) GPP R NEP Gross Primary Production, Ecosystem Respiration (g C m -2 yr -1 ) Figure 21.20 Ecological Climatology © 2008 G. Bonan