Disturbances often shape ecosystems by periodically reorganizing or destroying them, allowing for significant changes in plant and animal populations and communities.

Soil Moisture Responses to Short-Term Soil Manipulation Experiment


A short-term soil manipulation experiment has been conducted as part of the McMurdo Dry Valleys Long Term Ecological Research (LTER) project. The moisture content of soil samples collected for organism extraction and identification was determined. Samples were taken on November 13, 1995, November 17, 1995, November 24, 1995 and December 11, 1995.

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The experimental design is a randomized block, with 5 replicates per treatment. Within each block were 3 plots measuring approximately 1m x 1m, with a central circular area of 85 cm diameter (approx. 0.57 m2) used for treatments and sampling. The treatments were as follows: (C) control plots (no manipulations), (W) nanopure water added to field capacity to 10 cm depth (5.6 L/plot), (WS) sucrose added in solution (15.82 g sucrose in 5.6 L water per plot). 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 85 cm diameter circular area of each plot starting at the 12:00 position on the first day. The above treatments were then applied to the plots. The 3:00, 6:00 and 9:00 positions were then sampled for each successive date. The location of the sampling was recorded each time so that areas were not re-sampled. Using the plastic scoop, soil was collected to a 10 cm depth. Very large rocks (>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 5 degrees C 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. A sub-sample of approximately 50g was removed and placed in a pre-weighed aluminum soil can, and weighed on a balance accurate to 0.01g. This sample was dried at 105 degrees C for 24 hours. The sample was removed, placed in a desiccator to cool down, and re-weighed. These data were used to calculate water content of the soil.


This file was created by Mark St. John at Colorado State University on 11 Nov 1998, using raw data from the Excel workbook '9511stca.raw'. The file format was suggested by the LTER data manager, to conform with the relational database structure. On 4 Dec 1998, the file was submitted to Denise Steigerwald, the MCM LTER data manager, located at INSTAAR, University of Colorado. Upon arrival at INSTAAR, the data manager removed columns for latitude and longitude, and updated the location names to match those provided in the "soil measurement locations" file (from which latitude and longitude can be found). The resulting file was reformatted to present in ascii, comma delimited text and MS-DOS text (table layout) on the MCM LTER web site. Both of these files are linked to this web page above.


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