Characterizing Soils and Weathered bedrock across the Sierran developmental Sequence

• What are the chemical mineralogical and physical properties? • Can spatial variability be explained by Time, Topography,

Parent material, Organisms, and Climate explain? • Do digital soil mapping techniques work (terrain attributes,

airborne gamma ray mapping, remote sensing)?• Do spatial patterns in soil relate to trends in weathered

bedrock characteristics?• How does the degree of soil development influence processes

in weathered bedrock?• What is the role of weathered bedrock relative to resilience of

ecosystems to climate change?

Analysis to date: 3 cores at SJER to 2m;4 cores at soap root 2.5-4.5 m; 3 cores at providence 8-11 m

Chemical Physical Mineralogical

CEC/Base saturation

Texture(clay, silt, sand fractions)

Selective Dissolution Mn, Fe, Si, Al

pH Fine clay Quantitative XRD

EC Sand fractions Clay mineralogy

Total C & N Bulk density

Available P Porosity

Exchangeable K Ksat

Cl- Gravimetric water

Ca2+, Mg2+, K+, Na+

400 m 1100 m 2000 m 2700 m

Why is it shallower at 1100 m when soils are significantly more weathered?

Depth (m)

Depth (m)

Available H2O (cm/cm) Available H2O (cm/cm)

The Red Zone