The next Wormherder field trip was to sample another one of our core experiments, the elevational transect in Taylor Valley, on the south side of Lake Hoare. The purpose of this experiment is to determine if elevation affects soil biota and/or soil chemistry. The experimental design involves 3 different sampling sites, each at a different elevation; one low, one middle, and one high. A 3 by 3 meter grid has been established at each elevation site, and soil samples are taken within this grid for analysis back at the lab. The picture below shows the low elevation plots; if you look closely you can see the stakes that outline the sampling grid. This ensures we sample in the appropriate location from year to year.

Elevational Transect plots

One sample is taken within every 1 by 1 meter subplot in the large plot. The surface soil is removed to a vial for analysis of soil productivity. Then, soil is removed to a depth of 10cm with a scoop and placed in a sterile plastic bag. Below, Bishwo shows his soil sampling skills at the low elevation plot. Lake Hoare and Canada Glacier are visible in the background.

Bishwo sampling

For ease of sampling in the field (often in cold conditions), sampling kits are pre-assembled in the lab. For each sample, a fresh scoop, vial and bag are labeled and organized into larger bags. This helps to ensure that each sample gets taken and is identified properly. Why is this so important from a scientific standpoint?
Below, Bishwo displays a sampling kit for one of the elevation blocks.

Bishwo models sampling kit

The low elevation plot is located at approximately 272 feet above sea level, and from there it is an uphill climb to about 400 feet elevation to the mid-level study site. In following photo, Breana and Bishwo make the hike which offers a great look at Canada Glacier’s plunge into frozen Lake Hoare.

Bishwo and Bre to mid-ET

Soil samples are taken at the mid and high elevation sites, just as at the low elevation site so comparisons can be made between the three areas. What types of characters might vary between sites due to their elevation? Why might elevation be responsible for these differences? Below, two happy hikers, Breana and Karen, get ready to sample the mid-elevation block.

Breana and Karen, ready to sample

The high elevation site is located at around 615 feet above sea level and is the farthest from Lake Hoare. This plot lies beneath Andrews Ridge, which runs from east to west and is pictured below. The distance from the lake is one of the main physical variables that differs between the three elevation sites. Soil moisture properties may also vary between the study areas. Both of these factors, among others, may affect the distribution and abundance of nematodes and other soil organisms.

Andrews ridge, Taylor Valley

With sampling complete, the helo returned for pickup and whisked the Wormherders back toward McMurdo in order to process the fresh soil samples. Timing is critical since we characterize the proportion of live and dead nematodes of the different species, and survival can be affected the longer the samples remain outside a temperature-controlled incubator. On the way back, Canada Glacier revealed its full, spectacular self.

Canada glacier from air

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