PARENT SESSION
Poster Session #2: Carbon Storage.
Monday, August 5. Presentation from 5:00 PM to 6:30 PM. Exhibit Hall B & C, TCC

Soil carbon patterns in a semiarid pinyon-juniper woodland.

Reiley, David^*,1, Breshears, David², Zedler, Paul¹, Ebinger, Michael², Meyer, Clifton², ¹ University if Wisconsin-Madison, Madison, WI² Los Alamos National Laboratory, Los Alamos, NM

ABSTRACT- Pinyon-juniper-grassland complexes cover 60 million acres of the American west. An increase in tree and shrub components has occurred worldwide in the last century along the grassland-shrubland-woodland continuum. This woody encroachment may contribute to the "missing sink" of carbon noted in various evaluations of global carbon cycles. To evaluate the impact of woody encroachment, it is necessary to estimate the amount of carbon stored in biomass of canopy and intercanopy trees and grasses and in the soils beneath these vegetation types. It is also necessary to test if dominant species or relative patch age affects carbon storage. We evaluated 180 soil cores stratified from Pinus edulis and Juniperus monosperma canopies for three size classes, as well as grass patches, and bare patches associated with these canopies. Total and organic carbon were measured in different depth classes to the base of the soil, that is, to about 80 cm below the surface. We found that soil carbon was greater under tree canopies than grass patches or bare soil in intercanopy areas. Further, we found a correlation between soil carbon under tree canopies and tree diameters, implying that tree size and perhaps tree age play a role in soil carbon dynamics in semi arid landscapes.

KEY WORDS: carbon, pinyon-juniper, soil, encroachment