One of my goals during my research was obtaining enough data so that Nationwide Maps could be produced. The maps visually express the collected data from 331 trees located in 44 institutions. This information includes:

1) Quantity - Metasequoias planted before 1975. Trees planted after 1975 are far more common and may have not had adequate time to mature.
2) Height
3) DBH (Diameter at breast height)
4) Planting date
5) Seed source

Quantity Analysis

The first nationwide map describes amount of trees recorded at each site. This map shows the sites that have many trees with a larger tree icon, and the sites that have fewer trees with a smaller tree icon. This map first and foremost shows the institutions that have had a critical role in the young history of the Metasequoias. It displays the history that Harvard University’s Arnold Arboretum and U. C. Berkeley have in the discovery and distribution of the trees.

View a high resolution PDF image of the above file by clicking here.

Other institutions with many trees are the Dawes Arboretum and the Missouri Botanical Garden. These gardens have played important roles in history of the Metasequoia. The Dawes worked on understanding the nature of the mysterious and harmful ailment that afflicted Metasequoias called “inbreeding depression”, which made it difficult for local Metasequoias to breed because they were all descended from only a few trees in China.

Age Analysis

This map shows the average age of trees per site. All data was recorded in 2006, and accordingly all age calculations are based off of that year. This, as written on the Research Summary page, shows that trees typically did not reach the interior of the country until substantially later in time. Many trees on the East and West coasts were distributed from the Arnold Arboretum and planted between 1948 and 1950. Many other sites in the interior of the country purchased Metasequoias from a local nursery or other source in the 1950’s and 1960s.

View a high resolution PDF image of the above file by clicking here.

The map shows the results of a ratio between the height and DBH of the trees. Sites with taller trees with smaller bases have less breadth, and are labeled with smaller tree icons. On the other hand, sites with trees that are shorter and have larger bases have greater breadth, and are labeled with a larger tree icon.

View a high resolution PDF image of the above file by clicking here.

As mentioned in my Research Summary page, the most interesting discovery in this map is that trees in warmer climates frequently are taller with slimmer bases. This is shown at Callaway Gardens in Georgia, the North Carolina Arboretum of U. N. C., and the Huntington Botanical Gardens in Los Angeles. Other sites that featured particularly tall trees with small bases include the Dawes Arboretum and Stanley M. Rowe Arboretum in Ohio. On the other hand, sites with shorter trees and larger bases were at the University of Washington, the Phipps Conservatory, and Mount Auburn Cemetery.

This was an unexpected result, and I had not read or expected this prior to my analysis. This is an interesting phenomenon because it means that many Metasequoias in the south did not develop their traditional buttressed base.

The average ratings map displays each site with a tree icon that represents the overall quality and impressiveness of all of the site’s trees as a whole. As the Research Summary page details, this involves a theory that factors in height, DBH, age, and quantity of trees per site. The formula is available on the Top Trees page. This map clearly shows that Metasequoias thrive in particular temperate conditions. They fare poorly in Washington state, Vermont, and Chicago. The site with the best overall ratings were Princeton University and the Stanley M. Rowe Arboretum in Ohio. Other impressive sites included the Morris Arboretum, the Bernheim Forest Arboretum in Kentucky, the Secrest Arboretum in Wooster, Ohio, and Winterthur Gardens in Delaware.

View a high resolution PDF image of the above file by clicking here.

These sites are all in either the Delaware Valley region or the temperate interior forest region around Ohio and Kentucky. On the flip side, some of the sites that fared the poorest were the Phipps Conservatory in Pittsburgh, Cornell Plantations, and a handful of sites in the Chicago – Milwaukee region. These are all generally colder, windier areas in which Metasequoias can grow but generally not well.