1. Land use change and terrestrial carbon cycle Xiaojuan Yang April 17,2003

2. Outline Significance of land use change to terrestrial carbon cycle Data Approach Results and conclusions

3. 1.6 ± 0.86.3 ± 0.63.2 ± 0.21.7 ± 0.53 ± ??? The role of terrestrial ecosystem in the global carbon budget is uncertain

4. The net flux of carbon between terrestrial ecosystem and the atmosphere results from two independent processes: Direct human activity(deliberate) Natural causes(inadvertent) Changes in land use, harvest of wood….. Elevated CO2, nitrogen deposition,climate change…

6. Purpose Present an estimate of annual changes in terrestrial carbon storage and emission from land due to deliberate management of the land surface

7. Data Annual rates of land use change (expansion and contraction of agriculture area and rates of wood harvest) Carbon content of each ecosystem

8. Map of Nine geopolitical regions

9. Types of ecosystems Tropical moist forest Tropical seasonal forest Temperate evergreen forest Temperate deciduous forest Boreal forest Tropical woodland and shrub land Temperate woodland and shrub land Tropical grassland Temperate grassland Tundra Desert scrub Swamp and marsh Cultivated land Pasture land

10. Data on carbon

11. Biomass typeCarbon in vegetation (10**6g/ha) Tropical moist forest200-250 Tropical dry forest140-150 Temperate forest135-160 Boreal90 Woodland27-55 grassland7-10 Desert scrub3-6 The amount of carbon per hectare in the live vegetation of different ecosystem

12. Approach Accounting for all of the carbon on an affected unit of land: live vegetation, soil, woody debris, wood products. The fate of each of the components was tracked in a bookkeeping model For each region, each type of ecosystem, and each type of land use the area, carbon content, and flux of carbon were calculated annually

13. Area of cropland (a) tropical regions (b) temperate zone regions

16. Flows of carbon between the major components of terrestrial ecosystems and the atmosphere as a result of land use change over 140 year period 1850-1990

18. Conclusions Between 1850 and 1990, the area of cultivated lands, is estimated to have increased by more than a factor of 4, from about 320*10 6 ha in 1850 to 1360*10 6 ha in 1990 Total net flux of carbon from changes in land use is 124GtC over the period from 1850 to 1990 The annual net flux, globally, increased from 0.4GtC/yr in 1850 to 2.0GtC/yr in 1990 The most important land use change was the expansion of agriculture Emissions from tropical Asia, Latin American accounted for almost all of the global emissions.

19. References Houghton, R. A. 1999. The annual net flux of carbon to the atmosphere from changes in land use 1850-1990. Tellus 51B:298-313. Houghton, R. A., and J. L. Hackler. 2001. Carbon flux to the Atmosphere from land use changes:1850-1990. ORNL/CDIAC-131, NDP-050/R1. Carbon Dioxide Information Analysis Center, U.S. Department of Energy, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. Houghton, R. A., R. D. Boone, J. R. Fruci, J. E. Hobbie, J. M. Melillo, C. A. Palm, B. J. Peterson, G. R. Shaver, G. M. Woodwell, B. Moore, D. L. Skole, and N. Myers. 1987. The flux of carbon from terrestrial ecosystems to the atmosphere in 1980 due to changes in land use: Geographic distribution of the global flux. Tellus 39B:122-139.