"Bernd Heinrich"の名言
A tree starts out as we do, as the union of two haploid gametes, the egg and the sperm. Cells divide again and again to become embryos. An infinitesimally small number of embryos become seedlings, and out of these, a tiny subset become trees. Time may stand still for decades in some seeds that enter dormancy until conditions for growth become suitable. Time may stop for decades as the seedling exists in the shade, garnering just enough energy for survival but not enough for growth. Time speeds up as sunlight is reached and the tree explodes in sudden growth and then proceeds along its trajectory to reproduction, senescence, and death. In some trees, like the gray birch and balsam fir, maximum life span is usually shorter than our own. In many others it is close to ours, while in a few trees, including the bristlecone pines, a life span of four thousand years is not impossible. Bristlecone pines grow extremely slowly because they live in a cold climate (the White Mountains of California) and because they have little water and few nutrients. They nevertheless stay a step or two ahead of decay and death because the climate also dries their deadwood. It takes them thousands of years to experience the growth, and life, that a white pine in Maine experiences in two hundred summers. Trees must be growing to be alive, but different species grow, and therefore live, at very different rates. Thus, even to a tree, both time and life are relative.
