Soil Carbon in Greenbelt Park Jay S. Gregg May 10, 2006

Background The largest terrestrial carbon pool is in the soil, 1.5 to 2.5 times that of vegetation (Wang et al., 2002) This is one of the areas with the most uncertainty within the global carbon cycle (Wang et al., 2004). Land use and land cover change affects soil carbon storage (DeFries et al., 1999).

History prior to 1700s: forests of oak, walnut, poplar, and elm mid 1700s: first settlers, deforestation began 1742: Bladensburg founded, navigable waterways 1750s-1850s: land cleared, converted to tobacco agriculture 1850s-1900s: soil degradation lead to more corn and vegetable crops 1900s: farms abandoned 1910s: dense thicket 1920s: trees dominate : Greenbelt, MD built under New Deal, area scheduled to be converted to housing 1947: Land acquired by state for B-W Parkway 1950: National Park Designation

10 years after abandonment

20 years after abandonment

Questions What is the approximate soil carbon storage of Greenbelt Park? Is there evidence of past agricultural activities in the 13 C/ 12 C record?

Sample Location

Methodology 80 ml of wet soil collected at surface, 10cm, 30cm, 50cm, 70cm, 90cm depths Samples weighed, dried, reweighed Samples ground, and analyzed for carbon content

Percent Water Bulk Density Porosity Part I. Soil Characteristics

Part II. Carbon Content Standard method: C d = H x B x O C d = Carbon Density H = Thickness of soil layer B = Bulk Density O = Organic Carbon Content (Wang et al., 2004)

Part II. Carbon Content } dz = 1 mm z = 1 m x = 1 m y = 1 m Dry Mass i (kg) x Carbon i (%) = Mass C i (kg) etc. Mass carbon (kg per m 2 of land, 1 m deep)

Total Soil Carbon Storage Carbon per m 2 of land, 1 m deep: 1.15 kg Area of Greenbelt Park 4.76 x 10 6 m 2 Mass of Soil Carbon ~5500 tonnes ~about 25% of a day’s driving in Maryland

Part III. Evidence of Past Agriculture Soil Density (30 cm > 50 cm < 70 cm) Soil Porosity (30 cm 70 cm) Soil Carbon Content (30 cm 70 cm)

Part III. Evidence of Past Agriculture 13 C/ 12 C ratio? Because it’s lighter, 12 C is reacts more readily than 13 C in biological processes. Organic matter becomes 12 C enriched relative to the inorganic carbon pool from which it has been taken. Soils high in organic matter should have a lower 13 C/ 12 C ratio.

Determining the ratio: –Raw data in given as per mil difference from PDB (Pee Dee Belemnite) 13 C/ 12 C PDB ratio = Sample 13 C/ 12 C =(0.001 x  13 C ref + 1) x Part III. Evidence of Past Agriculture

Conclusions A profile sample allows an approximation of soil carbon storage for the park The data is consistent with past agricultural practices –HOWEVER, Because of cost, the sample size is small. More profiles should be taken and analyzed to better understand spatial variations and to minimize uncertainties

References DeFries, R. S., Field, C. B., Fung, I., Collatz, G. J., & Bounoua, L. (1999). Combining satellite data and biogeochemical models to estimate global effects of human-induced land cover change on carbon emissions and primary productivity. Global Biogeochemical Cycles, 13(3), Wang, S., Huang, M., Shao, X., Mickler, R. A., Li, K., & Ji, J. (2004). Vertical Distribution of Soil Organic Carbon in China. Environmental Management, 33(Supplement 1), S200-S209. Wang, S., Tian, H., Liu, J., & Pan, S. (2003). Pattern and change of soil organic carbon storage in China: 1960s-1980s. Tellus, 55B, Wang, S., Xu, J., Zhou, C., & He, C. (2002). Using remote sensing to estimate the change of carbon storage: a case study in the estuary of the Yellow River delta. International Journal of Remote Sensing, 23(8),

Acknowledgements Dr. Alan Jay Kaufman Chrissy France Nick Collins