1 May, 2002
Did anyone remember the definition of a snag?
A snag is a dead tree that is still standing. Snags were one of the major places that we looked to find beetles and centipedes. The beetles are picky about their dead trees and only live under the bark of dead Poplars. The centipedes are for more widespread and can be found under the bark of just about any tree type here.
While we were out collecting yesterday I got to see a number of examples of adaptations to extreme environments. One of the photos being attached to this entry is of a wild rose bush, very common around here. As you will see in the photo, the bush has some very nasty spines. The growing season here is so short that plants have to as much advantage of the season as they possibly can. Consequently, they must also protect their growth from previous years, otherwise the plants would have to start form ground level again every season. To avoid this, the plants find ways to protect themselves. The spiny wild rose is one example. One of the passages read in class this year was the essay for February in the Sand County Almanac by Aldo Leopold. In that passage Leopold spoke of the eternal battle between rabbits and young Oak trees. As the Oaks try to grow, the rabbits chew them down to the ground. The same situation exists here except that the role of the rabbit is played by the Snowshoe Hare. Without some sort of defense, the plants would all be chewed to the ground by the hares. Thus we have the spiny defenses of the wild rose. One additional example that I am trying to get a photo of, is a local willow bush. The willow produces a toluene based chemical that is toxic to the hares (and to Moose as well). Examples of chemical and physical defenses exist throughout these boreal woods.
Today for the most part has been a lab day. The snowfall predicted turned out to be minor in this area, but the region around Toolik Lake is under a blizzard advisory until this afternoon. The good news is that it will likely be clear enough for driving by Saturday.
Today I learned how to take a blood sample from an insect. Actually, since insects have an open circulatory system (for Biology students out there, an open circulatory system isŠ?), the fluid being collected is called hemolymph. It is a combination of a blood-like material and lymphatic fluid. I've attached some photos of the process, but basically you clip off a small segment of the insect and collect the ensuing droplets of fluid with a capillary tube. A standard quantity for collection is about 3 micro liters. This fluid will then be used to determine melting and freezing points for the insect's hemolymph. This can tell us how active the antifreeze proteins are in the insect. We also used a procedure to determine the actual freezing point of the fluids inside the insect, but that is a process I'll tell you about tomorrow.
Tomorrow we will be looking for new collection sites in the mountains around Fairbanks and hopefully determining the cold tolerance characteristics of the insects tomorrow evening.
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