uid=MCM,o=EDI,dc=edirepository,dc=org all public read 9597dica Diana Wall

Johnson Hall 107 Fort Collins CO 80523 US

Diana.Wall@colostate.edu http://wp.natsci.colostate.edu/walllab/ https://orcid.org/0000-0002-9466-5235 Ross Virginia

Hinman Box 6182 Hanover NH 03755 US

(603) 646-0192 ross.a.virginia@dartmouth.edu http://sites.dartmouth.edu/ravirginia/ https://orcid.org/0000-0002-0890-0981 McMurdo Dry Valleys LTER http://mcmlter.org/ John "Jeb" Barrett jebarre@vt.edu https://www.biol.vt.edu/faculty/barrett/index.html https://orcid.org/0000-0002-7610-0505 field crew Byron Adams byron_adams@byu.edu https://biology.byu.edu/adams-lab https://orcid.org/0000-0002-7815-3352 field crew Denise Steigerwald data manager Inigo San Gil

Department of Biology, MSC03 2020 University of New Mexico Albuquerque NM 87131 US

(505) 277-2625 (505) 277-2541 isangil@lternet.edu data manager 2014-11-12 English

Concerns over environmental disturbance in the McMurdo Dry Valleys are increasing with increasing foot traffic from tourists and scientist. The effect of pedestrian disturbance was monitored by comparing the species composition, depth distribution and soil properties between adjacent high-, low- and no- traffic sites. This study began in the austral summer 1995/1996.

chlorophyll a soil soil disturbance soil samples LTER Controlled Vocabulary Antarctica chlopophyl-A LTER soil soil biota Station Keywords disturbance population dynamics LTER Core Areas

This data package is released under the Creative Commons Attribution 4.0 International License (CC BY 4.0; http://creativecommons.org/licenses/by/4.0/), which allows consumers (hereinafter referred to as “Data Users”) to freely reuse, redistribute, transform, or build on this work (even commercially) so long as appropriate credit is provided. Accordingly, Data Users are required to properly cite this data package in any publications or in the metadata of any derived products that result from its use (in whole or in part). A recommended citation is provided on the summary metadata page associated with this data package in the McMurdo Dry Valleys LTER Data Catalog (https://mcmlter.org/data), and a generic citation may be found on the summary metadata page in the repository where this data package was obtained. When these data contribute significantly to the contents of a publication, Data Users must also acknowledge that data were provided by the NSF-supported McMurdo Dry Valleys Long Term Ecological Research program (OPP-2224760). This data package has been released in the spirit of open scientific collaboration. Hence, Data Users are strongly encouraged to consider consultation, collaboration, and/or co-authorship (as appropriate) with the data package creator(s). Data Users should be aware these data may be actively used by others for ongoing research; thus, coordination may be necessary to prevent duplicate publication. Data Users should also recognize that misinterpretation of data may occur if they are used outside the context of the original study. Hence, Data Users are urged to contact the data package creator(s) if they have any questions regarding methodology or results. While substantial efforts are made to ensure the accuracy of this data package (with all its components), complete accuracy cannot be guaranteed. Periodic updates to this data package may occur, and it is the responsibility of Data Users to check for new versions. This data package is made available “as is” and comes with no warranty of accuracy or fitness for use. The creator(s) of this data package and the repository where these data were obtained shall not be liable for any damages resulting from misinterpretation, use, or misuse of these data. Finally, as a professional courtesy, we kindly request Data Users notify the primary contact referenced in the metadata when these data are used in the production of any derivative work or publication. Notification should include an explanation of how the data were used, along with a digital copy of the derived product(s). Thank you.

https://mcm.lternet.edu/content/human-disturbances-effects-chlorophyll This is the plot for the Biotic Effects Experiment at Lake Hoare  162.876007080078 162.876007080078 -77.635002136230 -77.635002136230 1995-12-07 Metadata completed in 2016 - San Gil. This file was created by Mark St. John on 9 Nov 1998, using raw data from the Excel workbook '9512dica.raw'. The file format was suggested by the LTER data manager, to conform with the relational database structure. McMurdo Dry Valleys LTER http://mcmlter.org/ McMurdo Dry Valleys LTER http://mcmlter.org/ McMurdo Dry Valleys LTER

  Soils were sampled from three areas: heavy traffic (H), light traffic(L) and control (C) where soils had not been walked upon. Samples were taken for chlorophyll a analysis as follows: Soil was collected to 1 cm depth with a clean plastic spoon, excluding rocks with a diameter >5 mm. About 4 teaspoons of soil were placed into the vial, keeping the vial out of the light in a closed hand. The soil samples were stored in a light-tight bag, in a cooler for transportation. On return to the laboratory (within 8 hours of sampling), the soils were stored at +5C until further processing.   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. This 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. Each vial was mixed thoroughly, then centrifuged for 5 minutes at about 1800 RPM. 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, in to 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.   Calculation of chlorophyll concentration. The calibration curve that was constructed for the fluorometer had the following equation: [chlorophyll (ug/L) = (Fo-Fa)-0.4254)/2.2385]. The Fo and Fa figures were put in to this equation to calculate chlorophyll concentration. Subsequently, this figure was divided by 1000 to convert to ug/mL. Next, this is multiplied by 10 as the soil was extracted in 10mL of DMSO/90% acetone. Finally, this is divided by the fresh weight of the soil in g to give the concentration in ug chlorophyll per g fresh weight of soil. If the extract was diluted prior to reading on the fluorometer, the dilution factor (noted in the comments column) was applied at the end of the equation.  

9597dica 9597dica.csv 3337 1 0 \n column , " https://mcm.lternet.edu/sites/default/files/9597dica.csv LOCATION LOCATION Name of area where measurement was made string Name of area where measurement was made DATE_TIME DATE_TIME Date on which sample was gathered date mm/dd/yyyy SAMPLE # SAMPLE # Sample ID string Sample ID CHL-A (uG/G SOIL) CHLOROPHYLL-A (MICROG/G SOIL) Chlorophyll a concentration found in soil microg/gsoil 0.0001 real 0 1.00 Required Entry None given COMMENTS COMMENTS Helpful hints about the sample string Helpful hints about the sample FILE NAME FILE NAME Name of file in which data was stored string Name of file in which data was stored