If sunlight does affect the branch structure of a Beech Maple, then exterior trees branches would have an acute angle in relation to the ground, and an interior tree’s branch would have an obtuse angle compared to the ground. The amount of sunlight each interior and exterior branch receives should be similar. Trees with acute angles would have shorter distances between the cross branches, and in turn have higher weight stress and more load support. Therefore, exterior trees would be more prone to damage due to lack of support than interior trees because of their growth response to sunlight and overall structural development.
We wanted to look at tree or leaf structure for our lab. After our class decided to focus on landscape ecology, we decided to conduct an experiment on tree architecture. Through a significant amount of brain storming, we narrowed our ideas down from studying leaf structure to branch structure. We wanted to know how light affects branch structure and their stability in a Beech Maple trees. We decided on these specific questions because they will best reveal the architectural aspect in trees.
As a group, we planned to accomplish, and understand why a Beech Maple tree’s branch is constructed by the affects of sunlight. We will compare the angles and distances between cross branches, weight stress, stability through weather, and the amount of sunlight received on the interior and exterior sections of the forest.
This research is relevant because our section is looking at landscape ecology. This is interesting to our particular group because we are all architecture majors and wanted to investigate its relevance within nature.
Relevance of Our research question:
The article by Honda and Fisher in 1978 said that right and left angle branch angles would vary. To receive the maximum amount of light the tree will have either a very dense leaf layer or a loose one among its branches. Because tree branches are three dimensional, it is difficult to analyze them and their orientation. The different types of symmetry of the two branches “maximize,” leaf surface area for light. “When two new branch units arise from the distal end of a previous unit, there is a regular asymmetry in the branch angle.” Therefore, the main point in the article is that trees have a particular branch structure that collects a maximum amount of light. Tree angles are positioned where they are receptive to maximum sunlight. When the sun is low in sky, there is no direct sunlight into the interior of the forest. Areas that have sunlight overlap receive twice as much light. Also, the branches of the trees must be high enough to receive the light to compete with other trees. Therefore, all of these components of time, sunlight, and competition all affect how high the tree branches will grow.
In an article by Schreiner ET al (1996) explains how the structure of branches are very similar to the arterial system. Experiments have looked at segment radial and lengths and how they relate to branch angles as well as segment diameters. The geometric model investigates how structure relates to functional abilities. This model also shows how branch structure helps with its ability to reach light in order to grow.
An article by Perttunen (1996) describes how a model LIGNUM describes the structure of trees three dimensionally and how growth relates to this aspect. The growth of a tree is due to photosynthesis and based on the amount of light available to the tree. The segments are based on branch angles which are grown to receive ample sunlight. The angles allow the leaves to reach the amount of sunlight needed to grow annually.
The article by D.F. Robinson (1996) discusses the big picture of the study of tree architecture. Robinson discusses the different theories and models other scientists have created to describe tree architecture. He does mention Honda’s (1971) article, which focuses on regularities of length and angle in branching structures. It also mentions an article form Kuuluvainen (1992) that stated flat extended foliage is best shape for acquiring light at high altitudes. Additionally, the article goes into detail about the Halle and Oldeman theory about tree architecture and also basic terms for various forms of tree structure. Despite the very broad approach to the article it lays the foundation to then build upon in studying tree architecture.
There are great differences between different kinds of maple trees. For example, the wood of the red and silver maple trees are weak therefore the branches are prone to cracking under stress from high winds, heavy snow and even ice loads.
Another article by McClure states that within four species of maples: sugar, beech, red, and yellow establish patterns in their canopies according to their height growth, and gap formation. This is necessary for the trees to obtain sunlight, and proper nourishment. Beech maples especially grow more slowly than the others after gap formation, however, the beech maple did grow at a more constant rate and reached the proper height for nourishment over a thirty year period. Beech maples also have the oldest stems, and therefore, it can be hypothesized that beech maples’ branches are sturdy and can withstand high stress.
Our research relates to how the position of tree branches and trees in general affect or contribute to the area’s landscape ecology. During this project, we will hopefully be able to make a broader base of human knowledge on how structural nature develops. How we want to know how it is created in certain ways for survival. Similar to why and how buildings are designed architecturally. Comparable to trees, buildings are created to withstand abuse from weather. Both have asethic values as well as functional values to survive in an environment.
Materials and Methods:
We plan to locate and select a number of Beech Maples in the exterior and interior of the forest. Specifically, we will test three Beech Maples on the interior and exterior of different patches. For each tree, we will use a light meter at the first branch closest to the ground to test how much light is available to that branch during a 24-hour period, therefore we will compare our data between the Beech Maple trees in the interior and the exterior of the forest using Stat View, a computer statistics program. The light meter data should be similar between the low exterior branch compared to the obtuse interior branch because the tree situates it’s branches to gain the maximum amount of sunlight to grow.
To determine the different angles, we will use a protractor, record the data, and then compare. To determine the stability of the tree, we will record the number of inches the branch will move after the force is applied. We will take all the data and find the averages and statistics through the use of Stat View.
The experiment is statistically sound because we are using an odd number of tests, thus allowing for a proper average of statistics. Additionally, we are only looking at one specific tree to insure there is not a random sample statistic. We know this from statistical logic. We will insure unbiased results by observing different patches and looking at interior and exterior Beech Maple trees. We will record sunlight to be able to compare interior and exterior Beech Maple trees.
To ensure that the data collected by the class can be trusted, we will explicitly state the procedures for collecting the data. When we type up our procedures, we will indicate the importance of consistency in the data collection and analysis through repeated bold directions.
Protractor- visual observation to determine the angles of the tree branches
Light meter- placement for 24 hours in a specific location to determine to the amount of sunlight available at that time
Ruler- visual observation to determine flexibility of a branch
The class will take our hypothesis and test its acceptability by collecting data by using our same methods to conduct the experiment. The class will process the data to the extent of processing it to gain the averages of sunlight readings. The angles and the distance of movement of the lowest branch of interior and exterior Beech Maple trees. We will also be creating a model of our experiment to show the class.
We will provide a data sheet and Stat View will also provide the data results as well. The data will also be compared and analyzed by the class and through the use of Stat View, they will find the means and the histogram of the data.
Our timeline will consist of 24 hours of data collecting.
Our primary results are available through our own groups observation of the Beech Maple structure. We already know that an exterior tree has flexible structure due to the effects of weather (sunlight and wind specifically). We also know that interior tree branches have obtuse angles to the ground in order to receive the proper nourishment. In addition, we know that exterior trees are more susceptible to damage caused by man and/or nature. Further results to be included in the final report
To analyze our results we will find the means of the angles from the exterior and interior branches, the amount of sunlight received in 24 hours, the distance between cross branches, the weight stress, and stability of the trees. We will compare all the means of our data collected from the Beech Maple trees in the various patches, compare and contrast our results. As a result, we want the angles of the interior and exterior Beech Maple trees to be similar in each patch. All other data should be significantly different if it is in a group of exterior and interior beech maple trees within a patch.
Further Results to be included in final report.
Discussion and Conclusions:
Further results to be included in final report
1. Honda, Hisao; Fisher, Jack B. Science. New Series 199(1978):888-890
2. Robinson, D. F. A Symbolic Framework for the Description of Tree Architecture Models; Botanical Journal of the Linnean Society, 121(1996):243-261
3. Terbough, John. Diversity and the Tropical Rain Forest. New York, Scientific American Library, 1992.
4. , Structural Quantification and Bifurcation Symmetry in Arterial Tree Models Generated by Constrained Constructive Optimization; Department of Medical Computer Sciences. 1996(161-174)
5. Ledezma, G. A. Journal of Applied Physics. 82(1997):(89-100).
6. Thompson, Franklin J., The Urban Naturalist: Maple, 1988
7. McClure, Jan W., Forest Ecology and Management. 127(2000):181-189
8. Perttunen, J. Annals of Botany. LIGNUM: A Tree Model Based on Simple Structure Units. 1996(87-98).
9. Internet: “http://www.jstor.org”
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