Garden-scale GIS

Despite growing up in the DC area, this is my first chance to spend time in Georgetown. I had never even heard of Dumbarton Oaks prior to May of this year! I’m very thankful to John Beardsley and Gail Griffin for this opportunity to work here. The first half of the summer working as the GIS intern has been wonderful and I’m looking forward to the second half.

 Pruning wisteria in the summer is a Sisyphean task. These Urn Terrace tendrils grew in five days!

Pruning wisteria in the summer is a Sisyphean task. These Urn Terrace tendrils grew in five days!

Like Kate and Rosabella, the other Garden and Landscape Studies interns, I spend about two days a week working in the gardens with Dumbarton Oaks’ professional gardening crew. So far, I have worked in the central part of the gardens from the orangery downhill to the the ellipse fountain. I’ve done a little bit of everything in the gardens: weeding, watering, carrying pots, pruning wisteria (an almost constant job in the summer with all this rain!). I’ve enjoyed both working directly with the gardening team as well as the more solitary tasks where I’m kept company by the catbirds and chipmunks. Spending extended periods of time working in the garden has helped me appreciate the garden’s design and Beatrix Ferrand’s vision for the property.

My GIS work at in gardens is as varied as my work in the garden. This summer, I will update a few of Dumbarton Oaks’ maps, attempt to map the relationship between soil moisture conditions and tree infections, explore how native bees interact with the garden landscape. My main task this summer is to expand the garden’s GIS tree database to include trees in the non-public areas of Dumbarton Oaks. A previous intern, David Wooden, cataloged the trees in the public gardens during the summer of 2010.

DO_trees

Many gardens around the world have been converting their scattered paper records into a GIS database. Not only does the database allow you to plot the exact location of each tree, but also keep records of each tree’s condition and any disease treatment or maintenance work performed. The 2011 GIS intern, Charlie Howe, produced a user manual so that anyone on the garden staff can enter observations on trees throughout the year. The database uses unique ID numbers for each tree to relate spatial location with tables of non-spatial observation data. Each tree point is associated with three data tables: observations on the tree’s status, records of work done on the tree, and any photos associated with the tree. The database is and always will be a work in progress, and much of the data are sparse at the moment. In the future, we hope to include more photos of trees to visually track their condition over time.

An example tree point and associated data. Tree point highlighted in blue.

An example tree point and associated data. Tree point highlighted in blue.

To illustrate, the image above shows the Red Oak on the South Lawn near the Orangery. The tree point itself stores location and elevation data and is linked with four observations. The initial observation in 2010 was made by David who measured the tree’s diameter. The June 2012 observation recommends checking for bacterial leaf scorch. The March 2013 observation records bleeding canker and ambrosia beetle damage.

Left, bleeding canker on Red Oak (Quercus rubra) in the Green Garden. Right, Redbay ambrosia beetle (Xyleborus glabratus) in Florida, photo by Stephen Ausmus at USDA (http://www.flickr.com/photos/usdagov/8411820043/), used under CC BY 2.0 (http://creativecommons.org/licenses/by/2.0).

Left, bleeding canker on Red Oak (Quercus rubra) in the Green Garden. Right, Redbay ambrosia beetle (Xyleborus glabratus) in Florida, photo by Stephen Ausmus at USDA (http://www.flickr.com/photos/usdagov/8411820043/), used under CC BY 2.0 (http://creativecommons.org/licenses/by/2.0).

(An aside on a common tree disease: Bleeding cankers are dark, wet patches on tree trunks caused by a fungus-like organism called Phytophthora and are very hard to treat. Phytophthora lives in the soil and the cankers are exacerbated by wet conditions and existing tree wounds. The liquid oozing from the cankers is sweet and alcoholic and attracts ambrosia beetles and other boring insects looking for a meal. These secondary afflictions further weaken the tree and spread more Phytophthora.)

Hard at work! The diameter of a tree is a standard proxy for its overall size. Photo by Walter Howell

Hard at work! The diameter of a tree is a standard proxy for its overall size. Photo by Walter Howell

For the past two weeks, when I’m not out in the garden, I’ve been wandering around the property with measuring tape and clipboard in hand. Each tree in the non-public garden needs to be measured and checked against the database location from previous CAD surveying efforts. Many trees were removed and many new trees planted during the construction of the library a few years ago. Rectifying the data has been a challenge! Mapped trees in the area below the chicken coop and pit house were especially hard to located until I realized that the fence boundary was mapped incorrectly.

Left: field map of the area between the Dell and the Garden court. If you haven't taken a walk west past the library, come check out two lovely winding paths through the woods! Right: Trees to map and measure.

Left: field map of the area between the Dell and the Garden court. If you haven’t taken a walk west past the library, come check out two lovely winding paths through the woods! Right: Trees to map and measure.

In addition to my main work on the trees, I have been updating maps for the visitor’s brochure and for facilities management. The new visitor’s map will have better labeling of garden zones to help visitors learn about and better appreciate the garden’s design and history.

In-progress map of garden zones. Some names, extents, and locations may be labeled incorrectly.

In-progress map of garden zones. Some names, extents, and locations may be labeled incorrectly.

cf. Perplexing Bumble Bee (Bombus perplexus) near Hume, VA

cf. Perplexing Bumble Bee (Bombus perplexus) near Hume, VA

Some of my interests in addition to maps and spatial analysis are entomology and ecology. I’ve been assisting with a citizen science project monitoring bees in Virginia native grasslands and I’d like to use some of those methods to map how bees and other pollinators are using the garden landscape. Which garden zones attract the most pollinators? Where are the bees traveling across the garden? How can the garden be managed to promote healthy populations of native bees? With this project, I hope to produce a useful map for the garden and to help Dumbarton Oaks’ garden staff harness the powerful analysis, research, and decision making aspects of GIS.

About me: I’m currently earning a certificate in GIS studies while completing a Master’s thesis in Geology/Paleontology from Penn State. I studied Geology and Religion at William and Mary. In the near future I hope to combine my interests in GIS with citizen science, landscape use, and biogeography, into a fulfilling career.

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