Information Support
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Main Theme
Trees have the ability to expand tissues in two directions, elongation and diameter. These are called "meristematic" tissues. Most of the volume of any tree is dead tissue. Only the outer layers under the tree bark are alive. The "cambium" layer produces new phloem, to transport water and nutrients, and new bark tissue. At the tips of each branch, and at side buds, there are tissues designed to form new twigs. So, trees get longer and taller by growing at their tips, and then grow fatter by growing along the sides of trunks, branches, and roots. That's why a nail in a tree with not grow upwards. However, it may be eventually grown-over!
Major Points
We all know, and have been told, that you can tell how old a tree is by counting its rings. Although, it is surprising to know that most fourth and fifth graders don't know how many rings a tree grows in one year. At first, a person would think the answer would be "one". But, for whatever reason, the kids don't know that. The correct answer, however, is "two" rings each year. If a tree grew only one ring, how could you tell where one ring ended and the next ring began? You couldn't. In fact, this is the way some tropical trees grow, or they stop and start more than once per year. Therefore, in many tropical areas, trees cannot be aged by counting rings. However, in our north temperate forests, all trees grow two rings each year. The first ring, usually the wider, lighter-colored ring, grows in the spring. That's called "springwood". In the summer, the tree grows a different ring, both chemically and structurally, that is usually darker and quite thin. This is called "summerwood". By the end of July, the diameter growth ceases as the tree begins to prepare for the winter season.
BeLeaf It or Not! Video ProductionThe purpose for these videos is to INTRODUCE a few concepts for each episode topic. They are meant to be light-hearted and entertaining. Yet, the intention is to have both feet on solid science ground (biological, economic, social, et al.). We acknowledge that many of the topics are introduced or reinforced in school curricula at the fourth through seventh grades. So, these students, and their teachers, are the primary target audience. All of these topics can be more fully explored within the classroom setting or, in some case, be explored IN THE WOODS! With this in mind, these support pages are embedded into the Michigan Forests Forever website, which already houses a wide range of information about Michigan forests, designed for use by teachers. This entire project cost about $100,000. No small amount, of course. The primary authors were Bill Cook, Georgia Peterson, and James Ford. Additionally, most of the episode scripts were either drafted and/or reviewed by cooperating foresters, biologists, teachers, and other experts. If you're curious about who helped produced these videos, visit the "credits" page. |