SOILS_LANDSCAPE_CHANGE English utf8 dataset McMurdo Dry Valleys LTER http://mcmlter.org/ 2019-03-19 ISO 19115-2 Geographic Information - North American Profile Metadata - Data with Biological Extensions ISO 19115-2:2009(E) Biological responses to landscape change in the McMurdo Dry Valleys, Antarctica 2019-03-19 publication David Van Horn University of New Mexico https://www.unm.edu/ vanhorn@unm.edu pointOfContact documentDigital The McMurdo Dry Valleys, Antarctica, are experiencing rapid landscape scale change including increased glacial melt, the expansion of water tracks, thermokarst formation, an increase in the extent of the soil active layer, lake level rise, and altered stream flow. The impacts of these changes for biological communities are currently unknown. The goal of this study was to conduct surveys and experiments in three Dry Valley soil habitats that are expected to undergo change: water tracks, lake margins, and active layer profiles. Specifically, samples were collected from: 1) transects spanning dry-wet-dry soils in two water tracks in different lake basins, including three transects from each of three reaches for each water track, 2) experiments in which water and varying levels of salt were added to dry soils immediately adjacent to water tracks, 3) transects in lake margin soils in two different lake basins, including four transects perpendicular to each lake that span wet-to-dry soils, 4) experiments in which sterilized and non-sterilized lake water were added to dry soils adjacent to lakes, 5) the soil active layer from a total of eight soil pits in two different lake basins that were sampled at 5cm increments of depth, from the surface to 30cm or the permafrost, whichever was encountered first, and 6) experiments in which soils from the bottom of the soil active layer were moved to the upper layer and vice versa. Bacterial communities were sequenced for each sample and edaphic characteristics were measured for a subset of samples. Name: Renée F. Brown Role: data manager completed McMurdo Dry Valleys LTER http://mcmlter.org/ disturbance theme LTER Core Areas English This is the Taylor Valley, a subjectively approximated contour by San Gil. We use this to denote the geographical extent of studies that encompass the whole Taylor Valley. According to Wiki contributors, the Taylor Valley is the southernmost of the three large Dry Valleys in the Transantarctic Mountains, Victoria Land, located west of McMurdo Sound. The valley extends from Taylor Glacier in the west to McMurdo Sound at Explorers Cove at the northwest head of New Harbour in the east and is about 29 kilometres (18 mi) long. It was once occupied by the receding Taylor Glacier, from which it derives its name. Taylor Valley contains Lake Bonney in the west (inward), and Lake Fryxell in the east (coastward), and Lake Hoare, Lake Chad, Mummy Pond and Parera Pond close together between the two. Further east of Lake Bonney is Pearse Valley. Taylor Valley is separated from Wright Valley in the north by Asgard Range, and from Ferrar Glacier in the south by Kukri Hills. 163.624877929690 161.707763671880 -77.808487073526 -77.519802097166 ground condition 2015-12-15 2015-12-17 https://mcm.lternet.edu/sites/default/files/data/SOILS_LANDSCAPE_CHANGE.csv SOILS_LANDSCAPE_CHANGE eng; US McMurdo Dry Valleys LTER SOILS_LANDSCAPE_CHANGE Number of Header Lines : 1 Orientation : Column Field Delimiter : , false DATASET_CODE DATASET_CODE SAMPLE_NUMBER SAMPLE_NUMBER SAMPLING_DATE SAMPLING_DATE Date Time Format: mm/dd/yy LOCATION UWT = upper reach of the water track; MWT = middle reach of the water track; LWT = lower reach of the water track; LHSS = Lake Hoare South Shore; WHC = Worm Herder Creek POSITION Sampling position, where Inside = inside of the water track, and Outside = outside of the water track. DESCRIPTION Detailed description of the sample. Upper/Middle/LowerReach = the sampling reach for a given water track; Trans1-Trans3 = transects 1-3 within a given reach; OutL = sample taken from outside of the water track on the left side of the transect while looking downslope; OutR = sample taken from outside of the water track on the right side of the transect while looking downslope; WT1-3 = samples take within the water track from left to right while looking downslope. TRANSECT_LAT Latitude of the sampling transect. TRANSECT_LON Longitude of the sampling transect. BACT_FASTQ The url for the bacterial fastq file associated with this sample. See NCBI BioProjectID: PRJNA525069 PH pH of a 1:2 soil water extract. EC Specific electrical conductivity of a 1:5 soil water extract. SWC Soil water content determined by drying ~20 grams of soil PERCENT_N Percent soil nitrogen as determined by elemental analyses using dried, ground, acidified soils. PERCENT_C Percent soil carbon as determined by elemental analyses using dried, ground, acidified soils. D13C δ13C stable isotope value (expressed as per Mil (‰)) CN_RATIO Soil carbon to nitrogen ratio DBF https://mcm.lternet.edu/sites/default/files/data/SOILS_LANDSCAPE_CHANGE.csv dataset Bacterial 16S rRNA Gene Sequencing: DNA from 0.7 g of soil was extracted using the cetyltrimethylammonium bromide (CTAB) method. Dual-index paired-end amplicon sequencing of 16S rRNA genes was performed using V6 universal bacterial primers 939F 5’ TTG ACG GGG GCC CGC ACA AG-3’ and 1492R 5’-GTT TAC CTT GTT ACG ACT T-3’ on an Illumina MiSeq. The 16S rRNA gene sequences were trimmed and quality filtered using Sickle and paired-end reads were aligned and merged via PANDAseq. The Quantitative Insights into Microbial Ecology (QIIME) pipeline was used to analyze the reconstructed gene sequences. Unique 16S rRNA gene sequences or operational taxonomic units (OTUs) were identified by the 97% DNA identity criterion using UCLUST. A representative sequence was picked from each OTU and aligned using the PyNAST aligner and the Greengenes core set (v. 13_8) and given taxonomic assignments using the Ribosomal Database Classifier program.Edaphic Chemistry: Soil pH was determined on 1:2 soil/deionized water extracts using an Orion pH probe. Electrical conductivity of 1:5 soil/water extracts was measured with a Yellow Springs Instrument 3100 conductivity meter. Approximately 20g of material were subsampled weighed and dried for 24 hours at 100 degrees C. Soil moisture content was calculated by dry mass – wet mass / dry mass. Dry soil samples were ground with a mortar and pestle into a fine powder and then weighed into tin capsules (~15 mg) for isotope analysis. A step-wise acidification process was utilized to remove carbonates from the soils. Briefly, 50 mL of 1% HCl was added to each open capsule. In desiccators, the capsules were exposed for 24 h to the vapor from 100 mL of 32% HCl in a beaker. All samples were again wetted with 50mL of 1% HCl and put in the desiccator, where they were exposed for 32 h to the vapor from 100mL of 37% HCl. Samples were then dried in a drying oven for 3 days at 35°C–40°C. Carbon (δ13C) isotope values were measured using a Costech 4010 elemental analyzer coupled to a Thermo Scientific Delta V isotope ratio mass spectrometer at the University of New Mexico Center for Stable Isotopes (Albuquerque, NM). Stable isotope data are expressed as δ values using the equation δ13C = [(RSample  − RStandard)/RStandard] x 1000, whereRSampleand RStandard  are the ratios of 13C /12C for each sample and standard. The internationally accepted standard for δ13C is Vienna Pee Dee Belemnite (V-PDB). The units are expressed as permil (‰). Internal lab reference materials included organic sediment standards with δ13C values (± SD) of -24.5 ± 0.6. Analytical precision was estimated via repeated (within-run) measurements of these reference materials calibrated to internationally accepted standards; within-run standard deviation for all reference materials was ≤ 0.2‰. Metadata Access Constraints: none Metadata Use Constraints: none annually McMurdo Dry Valleys LTER http://mcmlter.org/ pointOfContact