1. Measuring spectral effects of Ca fertilization in red spruce foliage
...notes from the chlorophyll trench ( nm)
Will Kessler, M.S. Candidate Natural Resources

2. Objectives of the study:
Make comparative measurements of foliar Ca status, along with other cation nutrients following the 1999 Wollastonite (CaSiO3) addition.
Ca, Sr, Mg, Mn, Fe, Al, P, K
Characterize the foliar spectra of the spruce in a Ca-treated stand,
Current Year (CY... meaning 2007)
Third Year (3Y)
Whole Bough (WB)
Supplement these data with observations of general tree health

3. Study site: Hubbard Brook Experimental Forest (HBEF)
Located in the White Mts. near to Thornton, NH. An experimental forest operated by the USFS
Has been extensively characterized over 50 years of research using the small watershed approach - i.e. “what came out - what we measured going in = estimate of what we can’t measure”
Following the 20th century’s acid precipitation, an experiment was carried out to replenish the amount of Ca estimated to have been leached out of the forest soils...

4. October 1999: 0.12 kg / m2 supplied to an entire watershed (WS1)
Calcium treatment
October 1999: kg / m2 supplied to an entire watershed (WS1)
A nearby, probably-not-identical watershed (WS6) is used as a reference watershed

5. Sampling: August 2007
18 mature (at least 20 years old), dominant or co-dominant canopied spruce
(Picea rubens Sarg.), were selected from the Spruce-Fir zone of each watershed: Reference & Ca-treated
Each foliar sample was separated out into CY, 3Y, and WB for processing

6. Results thus far: Foliar chemistry (total cations) By needle age class
By treatment
Needle spectra (VIRIS)
By needle class
Correlations across treatment, accounting for needle class

9. Significant differences (P < 0
Significant differences (P < 0.05) in total foliar Ca, by treatment and by needle class

14. Ca-fertilized whole boughs scanned looked much different than the respective reference scans:
Higher % reflectance in nearly all TM band regions
In Ca-treated plots, higher NIR3/1 ratio, but lower RE3/1 ratio
Max reflectance in green (green-peak) and red (red-well) regions confirms observed differences in TM bands 2 and 3
Appearance of the Ca-treated curves is one of wholesale increase in reflectance: from nm

15. Why?
Could be that the Ca has stimulated a general foliar growth response in spruce trees

16. Why?
Oxalates of Ca may play a role in the optical density of a spruce needle, an increase in these crystal structures could promote a general reflectance response

17. Next: run correlative analyses on foliar chemistry and spectral data
Goal: support the experimental data from the watershed treatment with causal relationships

22. Future work:
CaOx forms and accumulates as a needle’s Ca supply increases, so the possible role should be testable with measurement of the crystal -Ox bound Ca component

23. Future work:
Use remote sensing data (Landsat 5, 7) evaluate the role of remote sensing tools to quantify cation concentrations - do the treatment effects show up over multiple satellite images from ?

24. Thanks to: USFS, Gloria Quigley for lab support
Mike Gagnon, Tricia McCarthy, the Gonz’ for field support
Forest Watch for the opportunity to speak