Evaluating the Drought Code Using In Situ Drying Timelags of Feathermoss Duff in Interior Alaska
Abstract
:1. Introduction
2. Objectives
- 1
- Determine the depth, bulk density, weight, and water storage capacity of black spruce-feathermoss duff from Wilmore’s measurements.
- 2
- Determine the properties of the soil represented by the water balance model of the DC by using measurements of water storage capacity, in situ drying timelag of the duff profile, and known soil attributes. Sequentially, this process is:
- 2.1
- Determine the drying timelag of a black spruce-feathermoss forest floor using a time series of in situ measurements of water storage and the relationships in Equation (1). Similarly calculate timelags of the DC over the same drying periods.
- 2.2
- Determine the potential evaporation rate at the surface of the forest floor from measurements of the water storage capacity (Obj. 1) and in situ drying timelag (Obj. 2.1) using Equation (1).
- 2.3
- Use the potential evaporation rate at the forest floor from Obj. 2.2 to determine the water storage capacity of the “DC equivalent soil” by setting the timelag in Equation (1) equal to the corresponding timelag of the DC.
- 2.4
- Determine the depth of the “DC equivalent soil” using its water storage capacity (Obj. 2.3) and measurements of component horizon bulk density, thickness, and maximum gravimetric moisture content from Obj. 1 using Equation (4).
3. Methods
3.1. Study Site
3.2. Soil Attributes (Obj. 1)
3.3. Determination of Timelags (Obj. 2.1)
3.4. Estimation of the Attributes of the “DC equivalent soil” (Obj. 2.2–2.4)
3.5. Evaporimeter and Thaw Depth Measurements
4. Results
4.1. Soil Attributes (Obj. 1)
4.2. Duff Timelag (Obj. 2.1)
4.3. Attributes of the “DC Equivalent Soil” (Obj. 2.2–2.4)
5. Discussion
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Abbreviations
Abbreviation | Definition |
Abbreviations | |
DC | Drought Code |
DMC | Duff Moisture Code |
FFMC | Fine Fuel Moisture Code |
FWI | Canadian Forest Fire Weather Index System |
Variables | |
D | Drought Code (Unitless) |
Actual evaporation (mm) | |
Potential evaporation (mm) | |
Gravimetric moisture content (%) | |
Volumetric moisture content (mm3 mm−3 or mm mm−1) | |
S | Water storage depth (mm) |
t | Elapsed time (d) |
w | Soil weight (mg mm−2) |
Depth or thickness (mm) | |
Soil bulk density (mg mm−3) | |
Density of water (mg mm−3) | |
Timelag (d) | |
Subscripts | |
Initial or yesterday’s value | |
Of the DC | |
Of the “DC equivalent soil” | |
Of the in situ forest floor soil | |
Equilibrium | |
Maximum | |
Conversions | |
w | 1 mg mm−2 = 1 kg m−2 |
1000 mm = 1 m | |
1 mg mm−3 = 1000 kg m−3 |
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Moisture Code | (mm) | Timelag (d) | Depth (mm) | Weight (mg mm−2) |
---|---|---|---|---|
FFMC | 0.6 | 0.67 | 12 | 0.25 |
DMC | 15 | 12 | 70 | 5 |
DC | 100 | 52 | 180 | 25 |
Duff | Approximate | Corresponding |
---|---|---|
Horizon | Thickness (mm) [18] | Moisture Code |
Live Moss | 0–30 | FFMC |
Dead Moss | 30–80 | DMC |
Upper Duff | 80–150 | DC |
Lower Duff | 150–200 | – |
Mineral soil | 200+ | – |
Soil Type | Horizon | Bulk Density | Thickness | Weight | |
---|---|---|---|---|---|
(mm) | (mg mm−3) | (mm) | (mg mm−2) | (mm) | |
Organic | 0–50 | 0.017 | 50 | 0.85 | 3.4 |
50–100 | 0.025 | 50 | 1.25 | 5.0 | |
100–150 | 0.042 | 50 | 2.10 | 8.4 | |
150–200 | 0.070 | 50 | 3.50 | 14.0 | |
Mineral | Each 50 mm | 1.40 | 50 | 70 | 10.5 |
Soil Type | Profile | Bulk Density | Weight | ||
---|---|---|---|---|---|
(mm) | (mg mm−3) | (mg mm−2) | (%) | (mm) | |
Organic | 0–50 | 0.017 | 0.85 | 400 | 3.4 |
0–100 | 0.021 | 2.1 | 400 | 8.4 | |
0–150 | 0.028 | 4.2 | 400 | 17 | |
0–200 | 0.039 | 7.7 | 400 | 31 | |
Organic + Mineral | 0–366 | 0.62 | 227 | 29 | 66 |
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Share and Cite
Miller, E.A.; Wilmore, B. Evaluating the Drought Code Using In Situ Drying Timelags of Feathermoss Duff in Interior Alaska. Fire 2020, 3, 25. https://doi.org/10.3390/fire3020025
Miller EA, Wilmore B. Evaluating the Drought Code Using In Situ Drying Timelags of Feathermoss Duff in Interior Alaska. Fire. 2020; 3(2):25. https://doi.org/10.3390/fire3020025
Chicago/Turabian StyleMiller, Eric A., and Brenda Wilmore. 2020. "Evaluating the Drought Code Using In Situ Drying Timelags of Feathermoss Duff in Interior Alaska" Fire 3, no. 2: 25. https://doi.org/10.3390/fire3020025