Climate Change Across Seasons Experiment (CCASE): A new method for simulating future climate in seasonally snow-covered ecosystems - Fig 2

<p><b>Soil temperatures from a) December 2013 to December 2014 and b) December 2014 to December 2015.</b> Soil temperatures averaged by treatment for 10 cm depth thermistors for each day.</p

Soil temperatures averaged by treatment for each depth (5, 10, and 30 cm) during one freeze-thaw cycle in winter 2015 in the <i>reference</i> (left), <i>warmed</i> (center), and <i>warmed + FTC</i> treatment (right).

<p>We used soil temperatures at 10 cm depth (thickest line) to operationally define one soil FTC. Note that while the temperatures at 5 cm depth are higher than 10 cm depth in the <i>reference</i> plots, they are not significantly different from each other.</p

Diagram of reference and heated plots, including wiring and conduit systems.

<p>Each plot is 11 X 13.5 m². Plots 1 and 2 are <i>reference</i>, 3 and 4 are <i>warmed</i>, and 5 and 6 are <i>warmed +FTC</i>. EPDM synthetic rubber roofing membrane material was installed to 30 cm depth between the two types of warmed plots (i.e., between plots 3–4 and 5–6) to inhibit roots from growing into different treatments. The parallel gray lines inside plots represent heating cable and the black lines outside plots represent heating cable conduit. The junction boxes, located along the conduit, are represented by white boxes. The equipment shed (center box) houses the control equipment for the experiment.</p

Mean snow (>0 cm, circles) and frost depth (<0 cm, squares) in <i>reference</i>, <i>warmed</i>, and <i>warmed + FTC</i> plots.

<p>Error bars are standard error of the mean. Upper figure contains data from the 2013/2014 winter and lower figure contains data from the 2014/2015 winter.</p

Total basal area of trees in each of the six CCASE plots.

<p>Values are totals per tree species within each plot measured in June 2012. Units are cm². There were no statistically significant differences in total basal area of individual tree species comparing reference (plots 1 and 2) to treatment (plots 3–6) plots (<i>P</i> > 0.05 for all tree species; see below) or for total basal area across all tree species comparing reference to treatment plots (<i>P</i> = 0.91).</p