Tree Canopy and Its Environmental Benefits
I-Tree Canopy is efficient and free software for calculating estimates of tree coverage and its environmental benefits in a predefined area based on Google Earth aerial photography. Using imagery of historical maps, I-tree Canopy also can study changes in canopy over time. The land cover data from I-Tree Canopy can be used by I-Tree Hydro to analyze the effects of trees on hourly stream flows and water quality.
A nice feature of I-tree Canopy is that everyone can learn to use it. The program asks the user 1) to delineate a geographical area, 2) to provide other types of land coverage categories besides trees (building, impervious, grass, etc.), and 3) to determine for each random dot the program creates in the delineated area on the map whether this dot is a tree or something else. The percentage of tree canopy is then determined by the number of dots classified as a tree. The more dots the user includes in the project, the greater the accuracy of the estimated tree canopy coverage.
I-tree Canopy is mostly used for geographical areas such as townships, cities, and counties. However, we chose Marquand Park to demonstrate its use. Based on just 200 data points, the results indicated that 51% of the park was covered by tree canopy (red dots), and 33% covered with grass (blue dots). The estimated environmental benefit of the tree canopy were relatively modest but the park is only a small 17-acre area.
We are looking forward presenting more information on some of our larger trees in the park and their relative environmental value using other I-tree features.
John Notman and Andrew Downing
John Notman, the architect of Guernsey Hall (the estate house of the property that is now Marquand Park), was born in Edinburgh, Scotland on July 7, 1810. He studied at the “School of Arts” also known as The Royal Academy of Scotland before emigrating to the United States in 1831. Notman arrived in Philadelphia with excellent drawing skills and a four-year apprenticeship which put him at great advantage to American practicing architects. He initially worked as a carpenter, quickly established his career as an architect around 1835, and eventually became well known for his designs of churches, private homes, and public buildings.
Notman was responsible for many of the great historic buildings that remain in Princeton, including Prospect House, expansions to Nassau Hall, and the Lowrie House, located at 83 Stockton Street. His biographer, Connie Greiff writes of Notman: “He introduced the Italianate villa to the United Stated at Burlington, NJ and was recognized by the chief apostle of the picturesque, A.J. Downing, as one of the country’s most skilled practitioners in that vein.“
The Princeton University Library has a drawing by Notman intended as a design for the garden of Guernsey Hall. It shows similarities to the current lay-out of Marquand park. In this drawing and an another for Laurel Hill, the first architecturally designed park-like rural cemetery in the country, the strongly influence of the landscaped garden principles of Andrew Downing on Notman can be observed in the meandering paths, clusters of trees, wide lawns, and open vistas. In his Treatise on the Theory and Practice of Landscape Gardening and essays published in his magazine, The Horticulturist, Downing popularized landscape gardening among America’s growing middle and upper middle classes. Following British models, he categorized landscape design styles as “The Beautiful” (calm and serene) and “The Picturesque” (dramatic), with the style to be determined by the existing landscape context. Proponents of the Picturesque strove to make “improvements” to the natural landscape. They aimed to perfect nature by considering the real site-specific characteristics of a place, the genius loci or what we might consider a “sense of place.” This might be realized by recognizing the topography of a site or framing a view of a borrowed landscape. These approaches often were employed on a single site. Olmsted, Downing, and Weidenmann all created picturesque landscapes, including many public parks. The picturesque style remained popular from the 1840s well into the early 20th century.