Lis Allison wrote, >Tundra happens when the temps stay low enough long enough that the frost >never completely leaves the ground, thus causing the next winter to add to >the existing frozen soil. If you think of a block of ice, say one cubic >foot, surrounded by air or warmish soil, it takes a certain amount of cold >to freeze it solid. If you take the same cubic foot of water and put it on >top of a solid block of ice, it will be easier (quicker) to freeze. Tundra >soil never completely thaws out, only the top thaws, and so the frost line >will be very deep indeed.
My first rock garden was in Fairbanks, Alaska, over permafrost, but as Lis writes the top layer did thaw annually, and very fast too. One evening I parked my truck next to the rock garden, and the next morning I came out to find it axle-deep in mud. Fortunately a friend and her Yup'ik boyfriend were staying with me at the time, and being from the Yukon delta he knew a whole lot about getting pickups out of mud. Having no alternative at that cabin, I would plant freshly gathered seeds of native alpines in pots in fall. Most would germinate immediately and soon be covered with snow. Almost all of them survived to resume growth in spring. Some of the native plants, however, such as the saxifrages and minuartias, were structured to retain their seeds in the capsules or fruits until the spring thaw, when they were released to germinate in the warming, wet, disturbed soil. I only wish I had realized at that time that I could have been growing high alpines from all over the world, but I thought only native plants could survive there. Still, having Loiseleuria and Diapensia on my little rock garden is a fond memory -- though spring break-up and not seeing anything grow for more than half the year are not so fond. Jane McGary Portland, Oregon, where the sun has finally appeared _______________________________________________ Alpine-l mailing list [email protected] http://mailman.science.uu.nl/mailman/listinfo/alpine-l
