3. Field Methods
•Pit location
• Away from trees
• Few surface rocks
• No recent disturbance
• Frame sits securely to soil
surface
•Dig pits
• Secure frames
• Quantitative sampling: Oie, Oa,
0-10 cm, 10-30 cm, 30-50 cm,
50+ cm, C horizon
4. Sequential Extraction Method
Volume Solution Temperature (˚C) Time Other
1. Exchangeable 5 mL 1 M NH4Cl
at pH 7
20 20 hr Shaker table
2. Cold Nitric 5 mL 1 M HNO3
at pH 0
20 20 hr Shaker table
3. Hot Nitric 15 mL 1 M HNO3
at pH 0
200 20 min Microwave
20 MPa
4. HF Digest 8 mL
1 mL
1 mL
HNO3
HCl
HF
210 15 min Microwave
20 MPa
Elements analyzed: Al, Ba, Ca, Fe, K, Mg, Mn, N, Na, P,
Rb, Si, Sr, Ti, and Zn
Slide adapted from Nezat 2005
5. Completing the Dataset (Summer 2018)
Sites Stand Elevation
(m)
Bedrock Years Excavated (# plots
sampled)
Bartlett
Experimental
Forest
C1 570 Mt. Osceola
Granite
2004 (3), 2010 (1)
C2 340 Conway Granite 2004 (3), 2010 (1)
C6 460 Conway Granite 2004 (3), 2010 (1)
C8 330 Mt. Osceola
Granite
2004 (3), 2010 (1)
C9 440 Conway Granite 2004 (3), 2010 (1)
Jeffers Brook
Experimental
Forest
JBM 730 Amphibolite 2010 (4)
JBO 730 Amphibolite 2010 (4)
Hubbard Brook
Experimental
Forest
HBM 500 Rangeley Schist 2018 (4)
HBO 500 Rangeley Schist 2018 (4)
Data used in: Blum et al. 2007 Nazet et al. 2007; Nazet et al. 2008; Schaller et al. 2008; Schaller et al. 2010;
Lucash et al. 2012; Vadeboncoeur et al. 2012; Vadeboncoeur et al. 2014;
6. Tree inventory, diameter growth, productivity
Litter production and species composition
Nutrient resorption from senescing leaves
Root biomass and production
Root proliferation in nutrient-amended cores
Soil respiration and belowground C allocation
Carbon and nutrient storage in soils
Enzyme activity, soil nutrient availability
Mycorrhizal infection and species composition
Soil fungi in nutrient-amended cores
Mineral weathering and rare earth elements
Seedlings, regeneration, herbs
Sap flow (transpiration)
Ideas for Field Measurements?
Join MELNHE:
http://www.esf.edu/melnhe/
we sequentially digested Two types of soil samples:
The samples were leached w/ 1M NH4Cl to remove the exchangeable fraction, then w/ 1M HNO3 to remove the easily dissolved minerals. The easily-weathered silicates were dissolved with 1M HNO3 at 200 C. The remaining silicates were dissolved with a combination of conc HNO3, HF, HCl which I’ll refer to as the HF digest.
Use to explain variations
Soil Respiration
Litter production and chemistry
Decomposition rate
N mineralization
Bedrock type
Growth responses
