Lab 1-FE.docx - Lab 1 Structure and Development of...

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Lab 1: Structure and Development of Even-Aged Stands Sarah Kerr For2060-004 February 16, 2016
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Introduction Trees, like all species undergo natural selection throughout their lifetime. In growing tree stands especially, the more favored trees are the ones that are thicker, taller, and get more sunlight. Thus the alleles on certain trees that grow faster and survive better in the environment will be passed on to the seedlings they drop. The weaker trees will lose the alleles of their poor traits over time, leaving room only for the strong trees in the genetic makeup of the stand. Therefore, as a stand first gets started there are many seedlings but as time goes on, most of them die out and the population regulates and fits the needs of the stronger trees through natural selection (Allen 1961). According to The Dictionary of Forestry (2008) a stand is a continuous group of trees that are of the same age-class distribution, composition, and structure. If a stand is pure than that means the trees within the stand are all of the same species and not mixed. Even-aged stands are all trees that are of a single age-class and all began their growth at about the same time. The tree stand studied in this lab was a pure, even-aged tree stand of 20 year old Loblolly pines. In F.S. Baker’s article titled “Notes on the Composition of Even Aged Stands” he states that there is a definite peak to the distribution of sizes. The peak then drops off on both sides regardless of age and average size of the trees in that stand. He found that there was a correlation between the number of trees/acre, the diameter size, and the age of the stand. In figure 2 of his work he shows that as the age increases in a stand so does the diameter of the tree at breast height. The number of trees however in the stand decreases as this happens. The reason for that leads back to P.H. Allen’s (1961) statement that trees die out over time, leaving only large trees because of natural selection when the species compete for resources in a beginning stand. F.H. Bormann (1965) explains it as a competition for resources where the energy made photosynthetically is stretched
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too thin over the stand, which cannot accommodate every species. Therefore he claims from his own experiments that the trees that survive are the large ones with a large diameter and height to get the most of the suns resources; height and diameter increase together throughout time. Shade- tolerant trees come into play later in the stand as they adapt to live among the giants. These trees that tower among the rest are known as dominant trees, followed underneath it by codominant, intermediate, and lastly suppressed. Suppressed trees are usually the ones to die out while a stand grows and ages for it cannot receive any sunlight as stated by Chadwick Oliver (1980).
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  • Fall '17
  • ian morrison
  • Inch, Pine, Eastern White Pine, Pinus classification, Loblolly Pines

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