page_title: Tree measurement
section_title: Tree shape
hierarchical_section_title: Tree measurement / Tree shape
caption_attribution_description: English: Ternary diagram plotting the shape of live oak trees based upon crown spread, girth and height
context_page_description: Trees have a wide variety of sizes and shapes and growth habits. Specimens may grow as individual trunks, multitrunk masses, coppices, clonal colonies, or even more exotic tree complexes. Most champion tree programs focus finding and measuring the largest single-trunk example of each species. There are three basic parameters commonly measured to characterize the size of a single trunk tree: height, girth, and crown spread. Additional details on the methodology of Tree height measurement, Tree girth measurement, Tree crown measurement, and Tree volume measurement are presented in the links herein. A detailed guideline to these basic measurements is provided in The Tree Measuring Guidelines of the Eastern Native Tree Society by Will Blozan.
  These are summaries of how to measure trees are also presented by various groups involved in documenting big trees around the world.
context_section_description: Different tree species tend to have different shapes and tree shapes also vary within a single tree species. As a general observation trees growing in an open setting tend to be shorter and have broader crowns, while those growing in a forested setting tend to be taller and have narrower crowns. In forested areas trees grow taller and put more energy into height growth as they compete with other trees for the available light. Often the tallest examples of many species are found where they are a secondary species on a site and competing for light with other taller tree species. The tall bay laurel (Umbellularia californica) at 169.4 feet discovered by Zane Moore in Henry Cowell Redwoods State Park is an example of an exceptionally tall understory tree growing among other taller species.
  Ternary Tree Shape Plots. A methodology for plotting different tree shapes graphically was developed by Frank using ternary plot diagrams. Ternary plots can be used to graphically display any set of data that includes three terms which total to some constant. Generally this constant is 1 or 100%. This is ideal for plotting the three most commonly measured tree dimensions. The first step in the analysis is to determine what an average shape for trees is in general. These three basic parameters can be expressed as a ratio of height to girth to average crown spread. Some trees are tall and narrow, while others are low and broadly spreading. The data used to determine the average tree shape is derived from a tabulation of the largest trees of each of 192 different species in the NTS 2009 dataset. The average girth, height, and crown spread values were calculated for the measurements included in the listing. For the dataset the average height was 87.6 feet, the average girth was 100.1 inches, and the average spread was 54.9 feet. It is not critical that these values be exact for analysis purposes. The next step is to standardize each measured parameter. The quantity measured for a particular tree is divided by the standard value as determined above. The next step is to normalize the data set so that the sum of the three parameters expressed as a percentage will equal one. This enables the shapes of different trees of different sizes to be compared. The final step is to plot these results as a ternary graph to better compare the results. As an example, the measurement data for 140 live oaks measured as part of the NTS Live Oak Project were graphically plotted using this process.
  The cluster representing the live oak data falls on the extreme edge of the general pattern of tree shapes. The height proportion exhibits a maximum of 17.23% of the shape value and a minimum of 6.55%, the girth (minimum of 19 feet in the data set) exhibits a maximum of 58.25% and a minimum of 40.25%, and Average Crown Spread maximum of 49.08% and a minimum of 30.92%. These points represent the measurements of the largest specimens of live oak measured in the field and typically represent open grown specimens, but the tightness of the shape cluster is still remarkable. It is even more interesting to note that while the data set contains both multiple trunk trees and single trunk trees, both plot within the same tight cluster.
caption: Tree shape diagram for live oak
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