Hemlock Removal Experiment - Coarse Woody Debris

Data

• hf125-01: coarse woody debris
• hf125-02: fine woody debris
• hf125-03: snags and stumps

Overview

• Lead: Aaron Ellison, Audrey Barker Plotkin
• Investigators: David Foster, David Orwig
• Contact: Audrey Barker Plotkin
• Start date: 2005-06-01
• End date: ongoing
• Location: Simes Tract (Harvard Forest)
• Latitude: +42.47 to +42.48
• Longitude: -72.22 to -72.21
• Elevation: 200 to 240 meters
• Taxa: Tsuga canadensis (eastern hemlock)
• Research topic: plot
• Study type: long-term measurement
• LTER core area: organic matter
• Keywords: forest dynamics, girdling, hemlock, hemlock woolly adelgid, logging, tree maps
• Release date: 2009
• EML version: knb-lter-hfr.125.4
• Revisions:
• Related links:
• Hemlock Removal Experiment - Understory Vegetation
• Abstract:

  The woody detritus survey is designed to measure coarse woody detritus that includes snags, logs, and stumps, and to estimate fine woody detritus which includes smaller pieces of downed wood. To capture both standing and downed wood, we based our survey around two main types of methods, the line intercept method and the fixed radius plot method. Below are the details of our woody detritus survey methods. Surveys have been completed for 2005 and 2007. The next surveys are planned for 2009 and 2011.

• Methods:

  1. The Line-Intercept Method for Downed Wood

  Within each of the eight 90m x 90m plots of the manipulation we laid out eight transects. As each of the line-transects converges in the central 30m x 30m plot we left a 5m x 5m square space in the center of the plot to define a boundary to keep each of the transects separate. Coarse Woody Detritus (CWD, wood pieces greater than 7.5cm in diameter) is measured along the entire transect length, and Fine Woody Detritus (FWD, wood 7.5cm-0.6cm in diameter) is measured along 2m a subsection of each transect.

  Coarse Woody Debris (CWD): the diameter, species (or species group) and decay class of each downed piece of wood that intersects the line-transect is measured using a 50cm caliper. When possible, two diameter measurements are taken, to account for the fact that most stems are not uniformly round. Location within 10-m section of the transect is also recorded. From there we can calculate volume per unit area by using the formula V= 9.869*(d /8L), where L is length and d is diameter squared (Harmon and Sexton 1996).

  Fine Woody Debris (FWD): FWD is tallied along a randomly selected 2m section of each transect. Downed wood that intersects the line-transect is tallied within two size classes: 0.6-2.5cm and 2.5-7.5 cm (Harmon and Sexton 1996). These size classes originally were used in fuel loading surveys. Species and decay class is not recorded for these size classes. From there we can calculate volume by converting size class to volume using size class averages of a particular diameter and secants of incidence angle (Harmon and Sexton 1996). We then use the equation V= 9.869*N*a(d /8L), where V is volume per unit area, d is the quadratic mean piece diameter for a size class, and a is the average secant piece along the transect (Harmon and Sexton 1996).

  2. Strip Plots to Measure Snags and Stumps

  To account for standing dead wood, we sample snags and stumps along a 4m-wide strip plot that straddles the line transect. Species (or species group) and decay class is recorded for each individual. To find the volume for snags and stumps we use the formula for the frustum of a cone which requires that we estimate the diameter of the wood at the top and measure the diameter of the wood at the bottom, as well as estimate its height. Getting these measurements for snags can become complex depending on the type of snag. For short snags and stumps, a 50cm caliper is used to measure top and bottom diameters, and a meter stick is used to measure height. For intact trees and tall snags, top diameter is visually estimated, and height is measured with a clinometer. For intact trees, top diameter is estimated as 1.0cm. Bottom diameter is measured with 50cm caliper. From these measurements we calculate volume as a frustum of a cone (Harmon and Sexton 1996).

  In 2005, mass of 33 intact trees was estimated using published allometric equations with diameter at breast height as the only input.

  3. Long-term Tagged Subset

  To understand how the woody detritus is changing over time we tagged all dead wood within one randomly chosen strip plot of each of the eight plots.

  4. Hollow Wood and Elliptical Wood

  Some special cases can arise where varying measurements will need to be made. When a piece of wood is hollow on the inside we will need to subtract out the volume of the hollows. This will be done by noting the exterior diameter of the piece of wood and the diameter and length of the hollow (Harmon and Sexton 1996). For pieces of wood that have an elliptical shape we will measure the maximum and minimum diameters and convert this to a round equivalent diameter using a version of the formula for the area of a ellipse A= D*D , and D = Square-root A (Harmon and Sexton 1996).

• Use:

  This dataset is released to the public and may be freely downloaded. Please keep the designated Contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.

• Citation:

  Ellison A, Barker Plotkin A. 2009. Hemlock Removal Experiment - Coarse Woody Debris. Harvard Forest Data Archive: HF125.

Detailed Metadata

hf125-01: coarse woody debris

1. year: year (YYYY)
2. plot: plot number (1-8)
3. tran: transect number (1-8)
4. loc: area along transect, in 10m increments
5. num: sequence sample number, not # in field; just to keep spreadsheet in order; integers except hollows which are integer.1
6. tlength: transect length (meter )
7. diam1: diameter 1. Field measurement, measured with calipers. (centimeter )
8. diam2: diameter 2. Field measurement. Measured perpendicular to diameter 1, if possible (e.g.; not possible if wood is sunk in ground) (centimeter )
9. diamavg: diameter average. SQRT(diam1*diam2) (centimeter )
10. decaycl: decay class (1-5). See methods. (number )
11. species: species, genus or major group
12. volumem3m2: volume, formula: 9.869*((diamavg/100)^2) /(8*transect length) (metersCubedPerSquareMeter )
13. densitygcm3: density by species and decay class; see methods; from Liu et al. (2006) (gramsPerCubicCentimeter )
14. masskgm2: mass, formula: density*volume*1000 (kilogramsPerSquareMeter )
15. notes: notes

hf125-02: fine woody debris

1. year: year (YYYY)
2. plot: plot number (1-8)
3. tran: transect number (1-8)
4. sizecl1: number of pieces in size class 1 (0.6-2.5cm diameter) along the 2m of the transect sampled (number )
5. sizecl2: number of pieces in size class 2 (2.5-7.5cm diameter) along the 2m of the transect sampled (number )
6. loc: start and end point (in m) of the fine woody debris subsample along the transect
7. volcl1: volume of FWD in size class 1. V= 9.869 * N * a * (dq2/(8L) See Methods (metersCubedPerSquareMeter )
8. masscl1: mass of FWD in size class 1. volcl1 * density (see Methods for site-specific densities by stand type & size class) (gramsPerSquareMeter )
9. volcl2: volume of FWD in size class 2. V= 9.869 * N * a * (dq2/(8L) See Methods (metersCubedPerSquareMeter )
10. masscl2: mass of FWD in size class 2. volcl2 * density (see Methods for site-specific densities by stand type & size class) (gramsPerSquareMeter )

hf125-03: snags and stumps

1. year: year (YYYY)
2. plot: plot number (1-8)
3. tran: transect number (1-8)
4. loc: area along transect in 10m increments
5. num: sequence sample number, not # in field; just to keep spreadsheet in order; integers except hollows which are integer.1
6. tlength: transect length (meter )
7. dbh: diameter at breast height used in allometric biomass equations for intact trees in 2005 only (centimeter )
8. dtop1: top diameter1, measured with calipers (centimeter )
9. dtop2: top diameter 2, measured perpendicular to first diameter, if possible (e.g.; not possible if wood is sunk in ground) (centimeter )
10. dtopavg: diameter average, formula: SQRT(diam1*diam2) (centimeter )
11. areatop: top area, formula: PI*r^2 (squareCentimeters )
12. dbot1: bottom diameter 1, measured with calipers (centimeter )
13. dbot2: bottom diameter 2, measured perpendicular to first diameter, if possible (e.g.; not possible if wood is sunk in ground) (centimeter )
14. dbotavg: diameter average, formula: SQRT(diam1*diam2) (centimeter )
15. areabot: bottom area, formula: PI*r^2 (squareCentimeters )
16. clindist: distance to tree used to calculate height with clinometer (meter )
17. clinbot: bottom clinometer reading, percent scale, used to calculate height with clinometer (dimensionless )
18. clintop: top clinometer reading, percent scale, used to calculate height with clinometer (dimensionless )
19. clinht: snag/stump height, formula: tree height= clindist*(clintop-clinbot) (centimeter )
20. height: snag/stump height, copied from clinht or measured directly with tape in field (centimeter )
21. type: category of dead wood
    • intact: whole standing dead tree
    • snag: broken dead tree
    • stump: cut tree
    • hollow: within a snag/stump
22. decaycl: decay class (1-5), see Methods (number )
23. species: species,genus or major group
24. volumecm3: dead wood volume, formula: frustrum of cone: Volume = height*(areatop + (( areatop* areabot )^0.5) + areabot )/3 (cubicCentimeter )
25. densitygcm3: density for 2007 only, by species & decay class; see methods; from Liu et al. (2006). This is embedded in mass calc. in '05. (cubicCentimeter )
26. massg: mass, formula: volume cm3 * density by species & decay class; see methods; from Liu et al. (2006) (gram )
27. massgm2: mass per unit area, formula: massg/(area) where area per strip plot = transect length * 4m (strip plot is 4m wide) (gramsPerSquareMeter )
28. notes: notes