1. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium1 Spatial and Temporal Patterns of the Contemporary Carbon Sources and Sinks in the Ridge and Valley Ecoregion of the United States Shuguang Liu and Thomas Loveland USGS National Center for Earth Resources Observation and Science Sioux Falls, SD 57198

2. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium2 Outline  The US Carbon Trends Project Research Questions Methodology  The Ridge and Valley Ecoregion Land Cover Change Spatial and Temporal Variability of C Stocks and Fluxes

3. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium3 Overarching Research Questions of the US Carbon Trends Project  What is the spatial, temporal, and sectoral variability of conterminous U.S. land cover change from 1973 to 2000.  What are the spatial and temporal distributions of carbon sources and sinks, and therefore the dynamics of carbon storage in the conterminous U.S.?  What are the major driving forces that dictate the evolution of US terrestrial carbon storage and the CO2 exchange between the land and the atmosphere?  What are the major uncertainties and knowledge gaps associated with estimating regional and national carbon dynamics?

4. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium4 US Land Cover Change There is no consistent database available that characterizes the contemporary US land cover change, because  Land cover change mapping over large areas is a major effort  Labor intensive  Money (funding sources)

5. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium5 Thousands of Sampling Blocks Sampling units are 20- or 10- km 2. Samples randomly selected within strata. Sample size based on expected spatial variability of change in the strata. US Land Cover Change Detection  Probability-based sampling strategy used to provide efficient and reliable estimates of land cover change over large areas. Goal is to detect within one percent of actual change at 85% confidence level.  Ecoregions are sampling strata  Land cover change was detected using Landsat images (i.e., 1973, 1980, 1986, 1992, and 2000)

6. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium6 Spatially Explicit Modeling GEMS (General Ensemble Biogeochemical Modeling System) oAn advanced modeling systems for spatially explicit simulation of biogeochemical cycling over large areas oDeveloped at USGS National Center for Earth Resources Observation and Science oDeployment of the encapsulated plot-scale model in space is based on a Joint Frequency Distribution of the major controlling variables (e.g., land cover, climate, soil, etc.). oIncluded data assimilation algorithms oIt includes a dynamic land cover/use change submodel oStochastic simulations to incorporate uncertainties in input data oUncertainty estimate of carbon dynamics oMajor applications (US, Africa, and Central America)

7. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium7 Land Cover: USGS Land Cover Trends Soil: STATSGO Climate: CRTUS2.0 (1900 – 2000) N Deposition: National Atmospheric Deposition Program Crop Information: USDA Agricultural Census Data FIA: Forest biomass, NPP, Age Distribution Thousands of Sampling Blocks GEMS Carbon dynamics simulated at 60 m x 60 m spatial resolution within 20 km x 20 km or 10-km by 10-km sampling blocks National Benchmark Databases Spatially Explicit Modeling

8. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium8 BlockEcoregion Nation Quantify the spatial and temporal changes of C stocks, fluxes, and uncertainty at various scales (10 km) (60 m resolution) Spatially Explicit Modeling

9. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium9 Ridge and Valley Ecoregion Geographic Location and Samples The ecoregion spans 8 states. A total of 40 10-km by 10-km sample blocks were randomly selected for land cover change detection and subsequent carbon simulations.

10. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium10 Ridge and Valley Ecoregion Land Cover Composition Around 1973 Forest: 57.1% Cropland:31.4% Urban: 7.9%

11. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium11 Ridge and Valley Ecoregion  Extensification of forest harvesting activities  Forest area reduction: for2trans > trans2for  Ag land reduction: ag2for  for2ag and urbanization  Urbanization (for2urban, ag2urban)  Annual change rate increases with time  Extensification of forest harvesting activities  Forest area reduction: for2trans > trans2for  Ag land reduction: ag2for  for2ag and urbanization  Urbanization (for2urban, ag2urban)  Annual change rate increases with time Land cover compositions (%) (A) Annual rate of land cover change during four time periods. (B) the total share percentage of six major land cover change activities (C through F) in the total change rate, and (C through F) the share percentages of the major land cover change activities. Land Cover Change 1973-2000

12. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium12 Forest Inversion FIA data: biomass stock by age class (therefore biomass accumulation rates implicitly used) and total standing biomass MODIS: annual NPP 2000- 2001

13. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium13 C Sink vs. C Sequestration C Sequestration = C Sink - C Removal and C Removal = GrainYield + WoodHarvested

14. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium14 Ridge and Valley Ecoregion Interannual and Spatial Variability (Blocks) Data show block-scale annual averages from 1973 to 2000; X axis shows spatial variability across 10-km by 10-km blocks; Y axis shows interannual fluctuations by blocks. Data show block-scale annual averages from 1973 to 2000; X axis shows spatial variability across 10-km by 10-km blocks; Y axis shows interannual fluctuations by blocks.

15. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium15 Ridge and Valley Ecoregion Interannual and Spatial Variability (Blocks) Data show block-scale annual averages from 1973 to 2000; X axis shows spatial variability across 10-km by 10-km blocks; Y axis shows interannual fluctuations by blocks. Data show block-scale annual averages from 1973 to 2000; X axis shows spatial variability across 10-km by 10-km blocks; Y axis shows interannual fluctuations by blocks. Net Primary Productivity (NPP) Total Carbon Stock Change Soil Organic Carbon Change Large interannual variability C sequestration strength increases from north (lower block ID numbers) to south; Large interannual variability Relatively smaller variability

16. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium16 Ridge and Valley Ecoregion C Stock and Land Cover Composition (Blocks) C stock at the block scale is 1.Positively correlated to forest fraction; 2.Negatively correlated to cropland fraction; 3.Not related to other land cover types. C stock at the block scale is 1.Positively correlated to forest fraction; 2.Negatively correlated to cropland fraction; 3.Not related to other land cover types.

17. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium17 Ridge and Valley Ecoregion C Sequestration and Land Cover Composition (Blocks) C sequestration at the block scale is 1.Positively correlated to forest fraction; 2.Negatively correlated to cropland fraction; 3.Not related to other land cover types. C sequestration at the block scale is 1.Positively correlated to forest fraction; 2.Negatively correlated to cropland fraction; 3.Not related to other land cover types.

18. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium18 Ridge and Valley Ecoregion Carbon Rich Gets Richer (Blocks) Soil sequestration accounted for about 35% of the total C sequestration Soil was a C source when total C sequestration was less than 50 g C m -2 y -1 C change rate in biomass and soils increases with total C stock

19. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium19 Ridge and Valley Ecoregion Temporal Change of C Stocks (Ecoregion)

20. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium20 Ridge and Valley Ecoregion Temporal Change of C Fluxes (Ecoregion)  Large inter-annual variability in NPP, C sequestration, and total C sink.  Soil C sink and total C sink is decoupled.  C sequestration is tightly coupled with C sink strength.  Harvested wood C increased over time because of extensification of clearcutting.  The average C sequestration rate was 96  12 (1  ) gC m -2 y -1.

21. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium21 Ridge and Valley Ecoregion C Sinks and C Sequestration (Ecoregion) C sequestration is tightly coupled with C sink strength.

22. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium22 Summary  Land cover change was very dynamic. Major changes include urban expansion, reduction in cropland area, and extensification of clearcutting activities.  Large spatial and inter-annual variability in NPP, C sequestration, and total C sink.  C change rate in biomass and soils increases with total C stock  Soil C sink and total C sink is decoupled.  C sequestration is tightly coupled with C sink strength.  Harvested wood C increased over time because of extensification of clearcutting.  The average C sequestration rate was 96  12 (1  ) gC m -2 y -1.  Soil sequestration accounted for about 35% of the total C sequestration. Soil was a C source when total C sequestration was less than 50 g C m -2 y -1

23. US Carbon Trends March 17, 20052005 USDA Greenhouse Gas Symposium23 Poster 312 Soil Organic Carbon Budget as Related to Land Use History in the Northwestern Great Plains