| Data Tables, Images, and Other Entities: |
| Data Table: | Units_and_Column_Descriptions
View Table Metadata |
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Short Name: | Elev_tran |
| Online Distribution Info: |
| Download File: |
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| Data Set Owner(s): |
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Individual: | Diana Wall |
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Address: |
| NREL, |
| Colorado State University, |
| Fort Collins, CO 80523 USA |
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Individual: | Ross Virginia |
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Address: |
| Environmental Studies Program, |
| Dartmouth College, |
| Hanover, NH 03755 USA |
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| Metadata Provider(s): |
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Organization: | McMurdo Dry Valleys LTER |
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Address: |
| Byrd Polar Research Center , |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Abstract: |
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Investigation of the effect of elevation and topography on soil biota and soil properties was part of the McMurdo
Dry Valleys Long Term Ecological Research (LTER) project. The number of soil organisms (nematodes, rotifers and
tardigrades), divided by species, sex and maturity was monitored at 3 elevations in Taylor Valley in order to accomplish this.
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| Keywords: |
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- soil biota
(theme)
- topography
(theme)
- nematodes
(theme)
- rotifers
(theme)
- tartigrades
(theme)
- McMurdo
(theme)
- Antarctica
(theme)
- LTER
(theme)
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| Additional Information: |
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| Notes about the attribute table |
Since the attribute table for this dataset is very large, the user must construct the actual column
name. The FIRST letter represents the species, and the following letters represent the life stage/sex/sum type. The nermatode
species codes are:
S: Scottnema lindsayae
E: Eudorylaimus spp.
P: Plectus spp.
For example, in the attribute table, "(code)ML" has the description "The total number of living male (species) adult nematodes extracted
from the soil sample in number of organisms per kg soil oven dry weight equivalent. In this case, a column name
called "SML" would be "The total number of living male Scottnema lindsayae adult nematodes..."
In the data, ND = no data; sample not taken
BD = below detection limit
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| Citation |
Powers LE, Ho MC, Freckman DW, Virginia RA. 1998. Distribution, community structure, and microhabitats of soil invertebrates along an elevational gradient in Taylor Valley, Antarctica. Arctic and Alpine Research 30: 133-141.
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| Preserved Samples |
Preserved samples are stored in the NREL Preserved Nematode Collection in
room 226, College of Natural Resources, Colorado State University. Original data are stored
in Room A208, Natural and Environmental Sciences Building, Colorado State University.
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| Notes |
Data contained in these files has been subjected to quality control standards
imposed by the investigator. The user of this data should be aware that, while efforts have
been taken to ensure that these data are of the highest quality, there is no guarantee of
perfection for the data contained herein and the possibility of errors exists. If you
encounter questionable data, please contact the MCM LTER data manager corrected or qualified.
Thus, these data may be modified and future data will be appended.
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| License and Usage Rights: |
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| MCM LTER data may be used freely with the following restrictions: |
The Principal Investigator be sent a notice stating reasons for acquiring any
data and a description of the publication intentions.
The Principal Investigator of the data set be sent a copy of the report or
manuscript prior to submission and be adequately cited in any resultant
publications.
A copy of any resultant publications should be sent to the McMurdo data
manager and principal investigator.
The end-user follow the guidelines set forth in the LTER Network Data Access
Policy, Data Access Requirements, and General Data Use Agreement found at
http://www.mcmlter.org/data_guidelines.htm
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| Geographic Coverage: |
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Geographic Description: | Study site is on the south side of Lake Hoare, Taylor Valley, Antarctica. Three plots were established with the following coordinates:
A77deg38'59"S, 162deg53'22"E;
B77deg38'06"S, 162deg53'20"E;
C77deg38'15"S, 162deg53'13"E
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Bounding Coordinates:
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| West: | 162.88 degrees
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| East: | 162.88 degrees
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| North: | -77.6 degrees
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| South: | -77.6 degrees
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Mimimum Altitude: | 83 meter |
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Maximum Altitude: | 188 meter |
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| Temporal Coverage: |
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Begin:
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End:
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| Maintenance: |
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Description:
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This file contains archived data pulled from Nemadisk and the field season directories by Jeb Barrett.
The data page contains the raw data for nematode abundance in # of animals per kg oven dry weight equivalent.
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Frequency:
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| Contact: |
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Organization: | McMurdo Dry Valleys LTER |
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Position: | Data Manager |
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Address: |
| Byrd Polar Research Center , |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Publisher: |
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Organization: | McMurdo Dry Valleys LTER |
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Address: |
| Byrd Polar Research Center , |
| 108 Scott Hall, |
| 1090 Carmack Rd, |
| Columbus, OH 43210-1002 USA |
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| Methods Info: |
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Description:
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Three sites were chosen on generally flat benches of the glaciated slope:
A at 83 m above sea level,
B at 121 m above sea level, and
C at 188 m above sea level.
A 20X 20 m grid was placed at each elevation, and soil samples were taken at the four corners of the grid, at the middle point of each side, and at the center of the square. A smaller 2 X 2 m grid was placed at the northwest corner of the larger grid, and samples were collected with the same scheme, though no second samples were taken from the overlapping corner.
Soil samples were taken for organism enumeration and moisture content analysis as follows: Sampling bags were prepared with one sterile 'Whirlpak' bag and clean plastic scoop per sample. Samples were taken from within the 10 cm diameter circular area of each plot. The location of the sampling was recorded each year so that areas were not re-sampled. Using the plastic scoop, soil was collected to 10 cm depth. Very large rocks (greater than 20 mm diameter) were excluded from the sample. The soil was shoveled into the 'Whirlpak' bag until three quarters full (about 1.5 kg soil). The soil was mixed well in the bag, then the bag was closed tightly, expelling as much air as possible. The soil samples were stored in a cooler for transportation. On return to the laboratory (within 8 hours of sampling), the soils were stored at +5C until further processing.
In the laboratory, soil samples were handled in a laminar flow hood to prevent contamination. The Whirlpak bags of soil were mixed thoroughly prior to opening. Approximately 200cm3 of soil was placed in a pre-weighed 800mL plastic beaker. Rocks greater than 3-4mm in diameter were removed from the sample. A sub-sample of approximately 50g was removed and placed in a pre-weighed aluminum dish, and weighed on a balance accurate to 0.01g. This sample was dried at 105C for 24 hours. The sample was removed, placed in desiccator to cool down, and re-weighed. These data were used to calculate water content of the soil, and to express data as numbers of soil organisms per unit dry weight of soil.
The remaining soil in the plastic beaker was weighed. Cold tap water was added up to 650 mL. The soil suspension was stirred carefully (star stir or figure of 8) for 30 seconds, using a spatula. Immediately the liquid was poured into wet screens - a stack of 40 mesh on top of a 400 mesh. The screens were rinsed gently with ice cold tap water (from a wash bottle) through the top of the stack, keeping the screens at an angle as the water filtered through. The water was kept on ice at all times. The top screen was removed, and the lower screen rinsed top down, never directly on top of the soil, but at the top of the screen and from behind. The water was allowed to cascade down and carry the particles into the bottom wedge of the angled screen. The side of the screen was tapped gently to filter all the water through. The suspension was rinsed from the front and the back, keeping the screen at an angle and not allowing the water to overflow the edge of the screen. The soil particles were backwashed into a 50mL plastic centrifuge tube, tipping the screen into the funnel above the tube and rinsing the funnel gently. The suspension was centrifuged for five minutes at 1744 RPM. The liquid was decanted, leaving a few mL on top of the soil particles. The tube was filled with sucrose solution (454g sucrose per liter of tap water, kept refrigerated) up to 45mL. This was stirred gently with a spatula until the pellet was broken up and suspended. The suspension was centrifuged for one minute at 1744 RPM, decanted into a wet 500 mesh screen, rinsed well with ice cold tap water and backwashed into a centrifuge tube. Samples were refrigerated at 5C until counted.
Samples were washed into a counting dish and examined under a microscope at x 10 or x20 magnification. Rotifers and tardigrades were identified and counted. Nematodes were identified to species and sex, and counted. Total numbers in each sample were recorded on data sheets. All species of nematode, and all rotifers and tardigrades found in the sample were recorded. Data were entered in to Excel files, printed, and checked for errors.
For measurements of pH, an aqueous soil solution was made. DI-H2O was added to soil in a 1:2 soil:water ratio in a clean, DI- rinsed glass beaker (coarse fragments >2 mm were removed). The samples were stirred until thoroughly mixed (about 5-10 sec). After sitting to equilibrate for 2 h (all years up to 2002-03) or 10 min (all years 2004-05 and later), the samples were stirred again and a reading was taken with a pH meter. For measurements of electrical conductivity, DI-H2O was added to soil in a 1:5 soil:water ratio. The samples were stirred until thoroughly mixed (about 5-10 sec). After sitting to equilibrate for 2 h (all years up to 2002-03) or 10 min (all years 2004-05 and later), the samples were stirred again and a reading was taken with a conductivity meter. For extraction of chlorophyll from the soil, all procedures were carried out in the dark or very low irradiance to avoid degradation of the chlorophyll. The soil samples were mixed thoroughly in the vials, and a sample of approximately 5 g was weighed out in to a 50 mL plastic centrifuge tube with a screw-top cap. 10 mL of a 50:50 DMSO/90% acetone solution was added to each sample and they were mixed thoroughly on a bench-top Vortex mixer for about 5 seconds. The vials were placed in a -4°C constant temperature room, in the dark, and left for 12-18 hours. Determination of chlorophyll a concentration was determined fluorometrically using a Turner model 111 fluorometer. A calibration using a known concentration of chlorophyll was carried out prior to sample analysis. The machine was blanked using a 50:50 DMSO/90% acetone solution. A sample of approximately 4mL of the DMSO/acetone solution was taken from the top of the sample with a pipette, being careful not to get any soil particles in the solution. The sample was placed in a cuvette, into the fluorometer and the fluorescence was recorded. This was done fairly quickly in order to prevent light from breaking down the chlorophyll. This measurement is called Fo, the initial fluorescence. After taking this reading, 0.1 mL of 1N HCl was added directly to the cuvette and the cuvette was gently agitated. After 20 seconds, the fluorescence was re-measured. (During this step, the acid converts the chlorophyll to phaeophytin by releasing a magnesium ion in an acidic environment). This measurement is called Fa, the fluorescence after acidification. The solution was discarded in to a waste container, and the cuvette rinsed 3 times with DMSO/90% acetone solution before proceeding with the next sample. For mineral N content, a 20 g subsample was extracted in 50 ml 2M KCl for 1 h and filtered through Whatman #42 filter paper. Extracts were frozen prior to analysis for NH4-N and NO2+NO3-N on a Lachat Quikchem. For total C and N, a subsample of soil was hand-ground using a sapphire mortar and pestle, from which a subsample was run on a Carlo Erba NA 1500 N Elemental Analyzer (Carlo Erba Instruments, Milan, Italy). For organic C, 1 mg of ground soil was acidified with 1 ml 6 N HCl and dried at 95°C for 48 h. A subsample was run on a Carlo Erba, and the value was corrected for the change in weight associated with acidification. Microbial C and N were measured using the chloroform fumigation extraction technique with a 1:2.5 ratio of soil and 0.5 M K2SO4. Approximately 20 g of soil from each sample was extracted in 50 ml of 0.5 M K2SO4. Extracts were shaken at 240 rpm for 45 minutes, then centrifuged at 15000 rpm for 15 min, and the supernatant brought to pH~2 with 0.5 ml 6N HCl. A duplicate 20-g subsample was placed in a vacuum desiccator and fumigated with ethanol-free chloroform for 120 h. After fumigation, soils were extracted as described above. All extracts were frozen prior to analysis on a Shimadzu TOC analyzer for DOC and DIN.
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