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Effects of Global Change on Grasslands and Feedbacks with Greenhouse Gas Fluxes

Explore the impact of global change on grasslands, focusing on the feedback loops related to greenhouse gas fluxes. Investigate the influence of climatic conditions, grazing pressure, soil properties, and nutrient management on grassland ecosystems.

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Effects of Global Change on Grasslands and Feedbacks with Greenhouse Gas Fluxes

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  1. Global Change Effects on Grasslands and Feedbacks with Regard to Greenhouse Gas Fluxes Klaus Butterbach-Bahl1,Xunhua Zheng2, Chunyan Liu2, Benjamin Wolf1, Wei Wei Chen2, Xinguo Han3 and Nicolas Brüggemann1 1Institute for Meteorology and Climate Research, Garmisch-Partenkirchen, Germany 2Institute for Atmospheric Physics, Chinese Academy of Sciences, Beijing, China 3Institute of Botany, Chinese Academy of Sciences . Beijing, China

  2. Forest Other Boreal Forest 17% Agro- ecosys. Temperate Forest 8% Tundra 11% Grassland Temperate Grassland 13% Scrub 3% Savanna 10% Desert 19% Tropical Rainforest 13% Mountains 6% Global importance of the biome type „grassland “

  3. Location of the target region

  4. Focus of MAGIM - I

  5. MAGIM core sites Hydrological measuring points IMGERS

  6. Climatic constraints  The climatic conditions limits NPP and make the steppe vulnerable to land use changes and grazing intensification

  7. Grazing pressure and degradation

  8. „Sustainable“ • Management • Meat/wool • Biodiversity • Water • Erosion • Atmosphere • ……. Soil properties Site/regional hydrology Plant production Species composition Biosphere/atmosphere Microbial turnover Erosion Nutrient export Feed quantity and quality Grazing effects Grazing

  9. Steppe degradation Degradation process September 2006 9.0 sheep/ha 1.5 sheep/ha

  10. Gross N turnover rates: Significant differences between grazed and ungrazed sites Holst et al., 2008, Ecosystemsc

  11. Grazed versus non-grazed steppe systems: N2O Soil T & moisture N2O-flux Soil N2O-concentr. 2007 2008

  12. Grazed versus non-grazed steppe systems: N2O Extremely high N2O-fluxes during freeze-thaw from ungrazed steppe  >70% of annual fluxes 2007 2008

  13. Do natural steppe systems emit more N2O than grazed systems? NO – On a regional scale nutrient management overrides site scale effects Holst et al., 2007, Plant and Soil

  14. Grazed versus non-grazed steppe systems: CH4

  15. Sheep CH4 emissions 10.8 -14.3 g CH4-C sheep day-1 1.1 mg CH4-C m-2 h-1 ≈ 70 kg C ha-1 growing season X0.02 = 1.4 kg C ha-1 ≈ 2.2 kg C ha-1 growing season X2 = 2.2 kg C ha-1 Do natural steppe systems take up more CH4 than grazed systems? NO – CH4 emission from riparian areas and from sheep are more important as CH4 uptake by steppe soils -50--60 µg CH4-C m-2 h-1 ≈2 kg C ha-1 growing season x0.98 = -1.96 kg C ha-1

  16. Summary • Grazing management has largely affected the biosphere atmosphere exchange of N2O: • decreasing winter emissions • increase in N2O emissions from sheep folds • as well as of CH4: • Decreasing uptake of CH4 • Increasing emissions from sheep • Understanding of GHG fluxes on a regional scale requires a detailed system analysis

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