1. Rangeland Soil Carbon: State of Knowledge
Justin D. Derner
and
Jack A. Morgan

2. Road Map Carbon cycle Terrestrial carbon sequestration Carbon credits
Definition
Importance of rangelands
Influenced by…
Experimental results
Gaps
Carbon credits
Offset project
Key points

3. Carbon Cycle

4. Carbon Sequestration - Terrestrial
Photosynthesis
Respiration
Storage of atmospheric carbon dioxide (CO2) in plant biomass and soil organic matter

5. Importance Mitigate rise in atmospheric CO2 Ecosystem co-benefits
Greater soil water holding capacity
Better soil structure
Improved soil quality
Enhanced nutrient cycling

6. Importance Rangelands occupy >50% of earth’s land area
830 million acres in US
15% of US soil potential for C sequestration
Contain 10-30% of global soil organic carbon
Could be released back to atmosphere with improper management

7. Influenced by… Climate Biome type Management Environmental conditions
Derner et al. (2006) Plant and Soil
Biome type
Conant et al. (2001) Ecological Applications
Management
Derner and Schuman (2007) Journal of Soil and Water Conservation
Environmental conditions
Ingram et al. (2008) Soil Science Society of America Journal

8. Influenced by drivers of…
Long-term changes in production and quality of above- and below-ground biomass
Long-term changes in global environment (temperatures, precipitation patterns, rising CO2) that affect plant community composition and forage quality
Drought effects on net C exchange

9. Experimental Results Grazing X Climate Grazing X Environment
Adding a legume
Different rangelands

10. Experimental Results: Grazing and Climate
Derner and Schuman 2007

11. Experimental Results: Grazing x Environment
Derner et al., in prep

12. Experimental Results: Adding a Legume
Derner and Schuman 2007

13. Experimental Results: NW rangelands
Svejcar et al. 2008

14. Experimental Results: Northern Plains rangelands
Svejcar et al. 2008

15. Experimental Results: SW rangelands
Svejcar et al. 2008

16. Experimental Results: Summary of different rangelands
Location
Vegetation
Mean (and range) annual net ecosystem exchange (g C/m2/yr)
Las Cruces, NM
Desert grassland
-160 (-254 to 94)
Lucky Hills, AZ
Desert shrub
-93 (-162 to 55)
Burns, OR
Sagebrush steppe
73 (-61 to 229)
Dubois, ID
83 (-47 to 260)
Mandan, ND
Northern mixed prairie
53 (-27 to 119)
Nunn, CO
Shortgrass steppe
107 (4 to 227)
Svejcar et al. 2008

17. Gaps Lack of soil carbon information for western shrublands
Accounting for total greenhouse gas budgets
Understanding management by environment interactions
Modeling capacity to temporally and spatially scale from site-specific findings to larger scales

18. Carbon credits – offset projects
Chicago Climate Exchange (CCX) developed sustainably managed rangeland soil carbon sequestration offsets in early 2007 (updated August 2009)
Scientific panel convened to determine sequestration rates with practices in land resource regions (expert input)

19. Benefits of offset projects
New income source
Reward sustainable ranching
Improved environmental quality

20. Land Resource Regions B F E G C H J I

21. (metric tons CO2/acre/year
Offset Rates
LRR Region
Offset Rate
(metric tons CO2/acre/year
Northwestern Wheat and Range Region (LRR B)
0.12
California Subtropical Fruit, Truck, and Specialty Crop Region (LRR C)
0.16
Rocky Mountain Range and Forest Region (LRR E)
Northern Great Plains Spring Wheat Region (LRR F)
Western Great Plains Range and Irrigated Region (LRR G)
0.27
Central Great Plains Winter Wheat and Range Region (LRR H)
0.20
Southwest Plateaus and Plains Range and Cotton Region (LRR I)
0.13
Southwestern Prairies Region (LRR J)
0.32

22. Economics – trade trends

23. Key Points
Carbon sequestration rates on rangelands are relatively low (0.07 to 0.30 Mg C ha/yr), but large land area available
Large soil carbon pools with about 15% of US potential for additional C sequestration
Improper management could release C stocks
Soil carbon sequestration characterized by short periods (2-3 months) of high C uptake and long periods of C balance or small losses

24. More Key Points
Sustainably managed rangeland soil carbon offsets available through CCX for many land resource regions
Western sagebrush dominated lands are a large gap in our knowledge
Uncertainty with greenhouse gas caps and regulations

25. Questions?