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Project TitleMELNHE Project: Fine-root biomass
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Field CrewNatalie Cleavitt (nlc4@cornell.edu); Alexis Heinz (akh24@cornell.edu); Cynthia Wood (cynthia@wood-fam.com)
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Lab CrewNeal Smeltzer (neal.smeltzer@coloradocollege.edu); Craig See (craigrsee@gmail.com)‎; Kikang Bae (kbae02@syr.edu)‎; Shinjini Goswami (shinjini.goswami@gmail.com); Lin Liu (ireneliulin@gmail.com); Christy Tanner (ktanner@linfield.edu); Amos Lim (zylim@syr.edu); Russell Auwae (rauwae@hawaii.edu); Kelly Nywening (kellynywening@gmail.com);
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Data entered by:Neal Smeltzer (neal.smeltzer@coloradocollege.edu); Cindy Wood (cynthia@wood-fam.com); Kelly Nywening (kellynywening@gmail.com)
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Principal InvestigatorTim Fahey (tjf5@cornell.edu])
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Research LocationBartlett Experimental Forest (sites C1-C9)
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Project DescriptionObtain soil cores at each of the Bartlett sites, compare fine-root mass for two different soil depths between nutrient amended plots
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Field Methods(Written by Alexis Heinz): Soil cores were collected from Wednesday, September 15, 2010 through Monday, September 20, 2010 from eight sites (C1 through C9, excluding site C3) at the Bartlett Experimental Forest in Bartlett, NH.
Cores of 50 to 60cm long PVC pipe were sharpened on one end with a sander and halved vertically. Halves were labeled to indicate pairs that fit together. About halfway through the soil collection, holes were drilled 2” from the top (unsharpened end) in the middle of both PVC halves.
Once in the field, matching halves were connected with two hose clamps, one about 3” below the top and one about 3” above the bottom (sharpened end). Cores often went into the soil more successfully and smoothly, i.e. when the core halves stay in line with each other, when the screw of the hose clamp was placed in the middle of a PVC half.
Within each plot, two soil cores were taken nearby each (between roughly 1-3 m away) of the five soil respiration collars (18” diameter teal green lysimeters), yielding 10 cores per plot and 40 per site. Soil core locations were determined by probing with a T-shaped soil probe to avoid rocks large enough to act as an obstruction. Cores were pounded into the ground to a depth of approximately 40cm to ensure a soil core of at least 30cm.
Cores without holes were initially removed by pushing the core side to side to loosen it and then pulling out by hand or by pushing the core in a circular motion and then pulling it out by hand. After holes were drilled into the two PVC halves, cores were later removed by sliding a 3’ piece of rebar or a soil probe through the two holes in the top of the PVC core. This was much easier and faster. The rebar worked better because of its density; a soil probe was broken in this manner.
Hose clamps were then loosened and one half of the PVC core was removed to expose the soil core.
The cores were measured from the top down. Cuts were made with a metal ruler or a spackling knife at 30cm and 10cm, in that order, to avoid contamination from upper to lower depths. Any soil >30cm was left in the field. Soil between 10 and 30cm was scraped into the appropriate bag in the direction of deeper layers on the PVC core with a metal ruler or spackling knife. The remaining soil from 0 to 10cm was then dumped into the appropriate bag in the direction of shallower layers with a metal ruler, a spackling knife, or by tilting the PVC core half at an angle.
At the end of each day, soil samples were placed in a freezer for storage awaiting analysis.
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Lab MethodsProtocol for Individually-Picked Root Cores (written by Cindy Wood):

Materials needed: glass vials with lids; tape (preferably lab tape); fine mesh sieve; ruler; tweezers

Tape and pre-weigh the vials (without caps). This saves having to remove the roots from the vials to weigh after drying (static from drying makes this very challenging!). I write the vial weight on the tape as it is easier to weigh a batch of taped vials and label later. The label should contain the following information: BEF; site, plot number, sample number (C6-1-1), core #1 or 2, depth (0-10cm or 10- 30 or whatever depth is written on bag); < 1mm or 1-5mm; date cores were collected.

Dump core into a fine mesh sieve (the Bartlett 2011 Crew used two layered sieves, the first was 2 mm mesh, the second was .25 mm mesh. Roots were picked from both layers, although almost all of the root mass was caught in the first sieve). Under running water, gently tease apart the core using fingers or tweezers, washing as much soil off as possible without breaking the roots. Transfer remaining contents of sieve to a paper towel or sheet of paper to absorb excess water. Transfer to a sheet of dry paper. I find it helpful to place the sample on one side of the paper and work on small increments, moving to the other side of the paper. Using tweezers and ruler, pick live roots from sample and place in the appropriate vials (most of the roots are <1mm). Any roots >5mm are discarded. It is sometimes necessary to separate <1mm rootlets from the 1-5 or >1-5 roots they are attached to. I use either the tweezers or my fingers to do so, but a razor blade sometimes comes in handy. It is important that no soil adhere to the roots as this will affect the dry weight. I will generally go through a sample a couple of times to make certain I have removed as many roots as possible. The 0-10cm samples are more difficult because of the organic matter. It is impossible to remove every little fragment! Use your best judgment. The remaining soil may then be discarded. Note: the live smaller roots will “snap” when pulled apart, whereas the dead will appear either dehydrated or mushy. The woodier larger roots are pliable when bent, if alive, whereas they break easily or crumble if dead. Generally, most of the <1mm roots are alive.

Store capped vials in refrigerator until you are ready to dry them. Dry (uncapped) at 60 C for two days. Weigh in the vials, if you already have the taped vial weights. Cap and store.

There are 320 cores at two depths for 640 cores total.
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Protocol for Root Subsampling:
1. Remove all bags from freezer for the plot to be sampled, check against the list of already completed cores from that plot (to ensure all bags to be pooled are present).
2. Separate the bags into four groups: 0-10 #1, 0-10 #2, 10-30 #1, 10-30 #2.
For each group to be composited:
3. Once thawed, combine all bags together
4. Pick out easily accessible larger roots. For the 0-10cm it may be tough to get most of the roots. This is fine, but try to get all over 1 mm in diameter. For the 10-30cm cores this will probably be most of the major root branches. Wash the roots that were removed, then sort into <1mm and 1-5mm diameter classes. Place into vials labeled with stand, plot, depth, number (1 or 2), diameter class, and the words “before composite”.
5. Homogenize the remaining composited soil and roots. It is very important to achieve a uniform mixture. It is possible to combine this with step 4. Steps 4-5 take approximately half and hour.
6. Weigh the composite and record on the datasheet.
7. Pour the composite into a cone shaped pile, then flatten this out into a cake.
8. Cut the cake into quarters using a knife. It is important to cut any roots under the knife, so that they are separated properly into their respective quarters.
9. Remove the two quarters opposite each other, then recombine, make another pile, flatten it, and quarter them again with the knife.
10. Again remove the two opposite quarters, re-pile, flatten, and quarter again with the knife.
11. Combine the two opposite quarters, and this is the subsample (it should be close to 1/8 of the original)
12. Weigh the subsample, and record on datasheet. Weigh the remaining portion of the composite, and record on datasheet. Since some soil and water leave the sample during the quartering process, a more accurate value for the total mass of the composite can be obtained by adding the subsample mass to the mass of the unused portion
13. Wash the subsample, and sort into <1mm and 1-5mm diameter classes. Place into vials labeled with stand, plot, depth, number (1 or 2), diameter class, and the words “subsample.”
In the end each composited group should have four vials: two diameter classes of roots picked from the composite pre-subsample, and two diameter classes from the subsample. These vials will be weighed at Hubbard Brook.
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Description of the spreadsheetThe data is split into two spreadsheets: one sheet for cores that were picked individually ("Individually-Picked Cores"), and a second sheet for cores that were composited by plot ("Composited Cores").
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NOTE: Any column in any sheet that is shaded blue or tan is for calculated values. No data should be entered in these columns.
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For "Individually-Picked Cores": The columns labeled "location", "stand", "plot", "collar", "core", and "depth" define each sample. There are nine stands (C1-C9). Each stand contains four plots (1-4). Each plot contains 5 collars (numbered, but not necessarily 1-5). Each collar has two cores (1,2), and each core is split into two depths (0-10 cm, 10-30 cm). The "Picked?" column is for keeping track of which cores have had the roots picked and sorted. The next set of columns are split into two groups, each group containing four columns: those labeled with a blue header refer to roots with a diameter less than one mm, and those labelled with a tan header refer to roots with a diameter of 1-5 mm. "Vial Mass" and "Mass of Roots and Vial" are measured masses. "Dry Root Mass" is a calculated value, equal to the difference between the two previous columns. "Root Mass per Area" is another calculated value equal to the root mass divided by the area of a core.
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For "Composited Cores": The first five columns again define the sample ("Subsample #" is for when two subsamples where taken from the same composite and compared). "Collar #'s Included" and "# of Cores Included in Composite" are the individual cores that are included in the composite. The next two columns with grey headers are for determining the fraction of the total composite that is made up by the subsample. Both of these values are taken after the big, easily-picked roots have been removed. The first grey column is the mass of all of the composited cores combined, while the second grey column is the mass of just the subsampled soil. The next group of columns with blue headers refer to roots with a diameter less than 1 mm, and those with tan headers refer to roots with a 1-5 mm diameter. Within each of these groups: "Vial Mass for Roots in Subsample" is the mass of the vial in which the roots picked out of the subsample were placed; "Mass of Vial and Roots in Subsample" is the combined mass of both the vial and the roots picked out of the subsample; "Mass of Roots in Subsample" is the calculated mass of the roots that were picked out of the subsample; "Vial Mass for Pre-Composite Roots" is the mass of the vial in which the easily accessible roots, removed prior to subsampling, were placed; "Mass of Vial and Pre-Composite Roots" is the combined mass of both the vial and the roots removed prior to subsampling; "Mass of Pre-Composite Roots" is the calculated mass of the roots that were removed prior to subsampling; "Calculated Total Root Mass" is equal to the mass of the roots in the subsample divided by the fraction of the subsample mass to total composite mass, added to the mass of the pre-composite roots; and "Root Mass per Area" is the calculated total root mass divided by the area of one core multiplied by the number of cores (assuming a core diameter of 5 cm). (NOTE: when two subsamples where taken from one composite, the mass of the pre-composite roots should be the same for both subsamples, and should be entered in both rows)
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The last spreadsheet, "Missing Cores," is a list of all cores whose whereabouts are unknown
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Sample Description and LocationPicked roots are stored in pre-weighed scint vials, and frozen until they have been dried and weighed. Current sample locations are listed in the last column of the spreadsheets
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Related Datasets
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Publications
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Known ProblemsNo cores were taken from site C3; there are a couple missing cores from sites C1, C6, and C9; there is varying accuracy to which the root masses were weighed (a portion of the samples were weighed on a balance that only measured down to 10's of milligrams); roots picked over the summer of 2011 were picked more thoroughly than other samples may have been, and thus may have greater root mass values
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CommentsNOTE FROM THE FIELD (by Alexis Heinz): A couple of the plots were weird. I can’t completely remember. In one of the mature sites (not C8, I think the one you walk downhill to get to and there is quite a bit of a thigh-high understory plant), there were only four soil respiration collars. The respiration collars were normally in the same subplots, so we just pretended there was a fifth collar and took soil samples in that area.