Aeolian Distribution of Soil Biota from Airborn Sediment Traps

TREATMENT Codes In the attribute table, the treatment is the manipulation for a give plot from where the soil was collected. The treatments are: (C) control plots (no manipulations), (T) enhanced soil temperature using ITEX conical open-top chambers made of solar fiberglass, (W) Nanopure water added to field capacity to 10 cm depth (5.6 L/plot) once per season, (TW) temperature enhancement and water addition Sample Codes In the attribute table, individual Bundt pans placed in each of three lake basins are designated by a sample number (1-9). 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. General Methods Three methods were used to collect wind-transported sediments and invertebrates. One was conducted by analyzing sediment accumulated on frozen lake ice or glaciers and the other two were conducted on land and collected windblown sediment after 1 year at two heights above ground level. Invertebrate diversity and nematode survival, active or live and immobile or dead nematodes were determined. 1. Sediment pockets on lake ice or glaciers: In the austral summer of 1997/1998, soil invertebrates were evaluated in pockets of soil sediments deposited on frozen surfaces of Lake Hoare (77 38 degrees S, 162 52 degrees E, elevation of 77 m asl) and Canada Glacier (77 37 degrees S, 162 59 degrees E, elevation of 264 m asl). Soil sediment pockets are formed as soil particles transported by wind and deposited on ice surfaces of lakes and melt glaciers. They may eventually melt into the ice forming biologically active cryoconite holes. These were sampled along three perpendicular transects of five sampling positions at varying distances along each transect wherever a soil deposit was found. The soil was collected with sterile plastic scoops and put into sterile Whirlpak bags - NASCO Plastics Inc., ON, Canada. The soil samples were stored in a cooler and transported to the McMurdo Station Crary Laboratory where they were stored at 4 C until processed. 2. Bundt pan soil traps: Bundt pans (Lancaster 2002) with approximately 25 cm diameter and 10–20 cm depth were mounted approximately 100 cm aboveground on PVC posts (Fig. 1) at three locations across Taylor Valley. Twenty seven Bundt pan traps, nine at each site, were placed along a transect on the south side of Lakes Fryxell (77 35 degrees S, 163 22 degrees E), and Hoare in the 1998–1999 summer season, and Lake Bonney (77 55 degrees S, 162 27 degrees E) in 1999–2000 summer season. Each pan contained about 100 glass marbles (1 cm diameter), on top of a coarse wire screen. The marbles and screen created a rough surface for trapping airborne particles and protecting them from being blown away. For sampling, the pans were removed, each covered with aluminum foil, and placed upright into polythene bags during transportation to prevent sediment loss. A portion of the amount of sediment collected in each Bundt pan was weighed and soil moisture determined gravimetrically by oven-drying a sub-sample of known weight at 105 C for 24 h. Soil invertebrate numbers recovered were expressed as per dry weight of soil. 3. Open top chambers at ground surface: The open top cone-shaped chambers complemented the Bundt pans, and targeted sediment transport just above ground level (less than 1 m). The OTCs were placed on level ground surfaces (less than 3–4% slope) at the south side of Lakes Fryxell, Hoare and Bonney in the summer of 2001–2002. Three plexiglass chambers (85 cm bottom diameter and 50 cm top diameter; Sun-Lite , Solar Components Corporation) were anchored into the ground with four metal stakes and a heavy gauge wire harness. The chambers were spaced 3 m apart along a (N–S) line perpendicular to the valley floor. An empty red polyester cloth formed into a wire supported box (50*50 cm2 and 10 cm height) was placed in the center of each chamber and anchored to the ground with nails at each corner and center of the box. At each sampling the chamber was removed, the cloth box with accumulated sediments dislodged by wind was cleaned into a plastic bag and transported to the laboratory, stored and analyzed as detailed for the Bundt pan traps. The transport collect ion method of soil to lake ice and glacier was sampled once, and the other two methods annually (2 years for OTC traps, and 5 years for the Bundt pan sediment traps). For all studies, nematodes, tardigrades and rotifers were extracted within 48 h of sampling from 100-g soil subsamples, where possible by wet sieving followed by centrifugation. Nematodes, tardigrades and rotifers were counted, nematodes identified to species, and classified as active (living) or immobile (dead), male or female, adult or juvenile. Invertebrate abundance was expressed as kg 1 of dry soil before log (n+1) transformation for statistical analysis using analysis of variance in JMP 501. The annual amount of aeolian deposition was calculated based on the formula: aeolian deposition (g m -2 year -1) = mass of sediment retained (g) x area of dust pan or OTC (m2) x time exposed (year). Bundt Pan Construction Materials: 1 bundt pan, approximately 25cm in diameter and 10-20cm in depth 100 plus or minus 10 glass marbles (1 cm dia) coarse metal screen (0.5 cm openings) pvc pipe (approximately 70 cm in length) 1 wooden block 5 screws (1 large, 4 small) 2 washers (1 large, 1 small) Cut one end of the pvc pipe at a 45 degree angle. At the other end, two holes must be drilled through each side of the pipe to accommodate the screws that will hold the wooden block. The wooden block must be cut to fit inside the pvc pipe and should be drilled with complimentary holes, including one on the top for the screws. Once the wooden block is secure within the pipe, the post can be pounded into the ground. The final height of the bundt pan, once fully assembled,should be between 40-45 cm tall , but security is more important than height, so some are taller than others. Place the bundt pan on top and secure with two washers (see diagram) and the screw. Cut the screen to fit approximately half way down into the bundt pan. Place the coarse screen in the pan, then add the marbles.