Long-term plant community monitoring in Old Crow
Temperatures at Old Crow
Mean Summer Temperatures
Arctic Borderlands Ecological Knowledge Co-op
What is happening?
- These graphs show how soil temperatures change during the year at different depths. Data collection began at two forested sites in Old Crow in July 1997 and there is a long term set of data from Eagle Plains (just a little over a year's data is shown here).
- The temperatures at 20 cm (purple line) warm up much more during the summer than the deeper soil at 50 cm (blue line). However, the deeper soil does not get as cold during the winter. Twice a year the temperature at 20cm and 50 cm is identical for a few days.
- Soil temperatures at Eagle Plains seem to fluctuate over a wider range than Old Crow. Notice that at both Old Crow sites the 50 cm deep soil never actually reaches freezing (flat line in the summer).
Why is it happening?
- Soil temperatures depend on both the warmth of the air above the ground and the ability of that warmth (or cold) to penetrate into the soil. A thick layer of ground vegetation, especially moss, will limit the amount of heat the soil can absorb during the summer. The greater range of soil temperatures measured at Eagle Plains compared to Old Crow probably reflects a difference in plant cover at the two sites. Other soil characteristics, such as soil moisture, may also be involved.
- Both Old Crow and Eagle Plains are underlain by permafrost (permanently frozen ground). The fact that the deep temperature probes at Old Crow do not reach a temperature above freezing indicates that the probes are located below the bottom of the active layer (the portion of the ground that thaws during the summer). If the active layer deepens, temperatures measured at these probes should increase to above freezing.
Why is it important?
- Climate change could have significant impacts on northen ecosystems if it allows the permafrost under the surface to warm up and eventually melt.
- Soil temperatures can provide a long term measure of how the climate is changing because soil temperatures, especially at deeper levels, tend to reflect long term changes.
- The data for Eagle Plains are unpublished data provided by Scott Smith, Research Branch, Agriculture and Agri-Food Canada.
- The data collected in Old Crow were started in 1997 as part of study of Long-term monitoring of vegetation and soil temperatures at Old Crow