Comprehensive Arboretum Tree Survey

Geog 399 Spring 2010

"CATS... I love cats!" — Travis


Introduction
The Long Tree Survey is a "practicum" in field mapping, currently focused on surveying the "index trees" at the Lyon Arboretum. It is organized as a group of coordinated directed-study (i.e. 399/699) courses through the UH Mānoa Geography Department, and builds on decades of involvement between the Department and the Arboretum. Although initially conceived as an follow-up to the field-mapping class (Geog 472), to hone surveying skills through a semester-long project, several students have participated while or before taking 472, and anyone interested in participating should contact us for more information. The advisor for this project is Ev Wingert; some of the organizational work is done by David Strauch.
Background

The Lyon Arboretum, planted in the early part of the 20th century and incorporated into the University of Hawai‘i in 1953, has been an ideal place for Geography students to practice a variety of field-mapping techniques. In the 1970s, work focused on collecting trails data as areas were cleared. This was done without georeferencing, using a floating autocad plot of extremely variable accuracy. The first years were hand plotted in ink with each years data added to the master.

More recent work has focused on bringing trails and trees in the Arboretum into UTM NAD 83 coordinates. Starting in about 1996, we worked at bringing control from Pu‘u Pia using survey grade GPS on campus as our reference station. This worked for the visitor center area but we could not get good enough satellite coverage to extend it further inland.

About three summers ago, the Arboretum hired several Geography students to start surveying the anchor or index trees and extend earlier survey work along the road. Because of various setbacks, this project did not get too far, but it did accomplish a good tie to the control point work, a map of all the tagged trees with dbh below the visitor center and a very detailed survey of the road edge and some of the reference pole markers along the road up to the seismic station. Some of the index trees above the parking lot were also surveyed but not many.

Using the street monuments, Pu‘u Pia and the then just released NGA photos, we shifted the floating survey into the real world State Plane and then to UTM NAD 83. From that point forward all of the class trails work was tied to that base map. However it is not adequate for GIS work beyond the surveyed area. We found there was an error in the original basemap of the road that we had used for 20 years for plotting trails making a lot of that work questionable.

In fall 2008, the closing exercise for the fieldmapping class was to map the index trees in Sections 22 and 23, which had been tagged for an earlier attempt at georeferncing via trilateration. Part of that work was useful and part was not, since there was a transcription error in one of the road control points which messed up the work in section 23. In fall 2009 the current form of the project began, with the formation of the Mapping Independent Study Team, which resurveyed the missing or questionable parts of Sections 22 and 23, and integrated this with earlier data. We are currently working on sections 24 and 25, and have extended survey control into areas both above and below the road. As we progress, we are building a spreadsheet which integrates survey data, including elevation and tree diameters, with Arboretum records, which will be used for attribution in GIS files.

What we'll be doing
Surveying in the Arboretum

The usual workflow of our project begins with a meeting in the parking lot of the Arboretum to check on and distribute the survey equipment. With a crew of 3-5 people, we have typically been using one Total Station with two prism rods; if more partipants join the project we might bring more than one station. Sometimes we store equipment in Ray Baker's office at the Arboretum, but schedules don't always permit this, so we more usually bring it from the storeroom at PSB. In addition to the station and rods, we bring radios, fieldnotebooks, measuring tapes, flags and pins for marking points, and —last but not least!— recharged batteries for the radios and the station.

Once we're all there, we head up to the section of the Arboretum where we're currently working, and set up the station on a known point, which we have previous surveyed. After orienting it to another known point, we begin to survey trees by placing a rod in the center of the trunk as seen from the station. Because this only gives us the location of the side of the tree, we also measure the tree's circumference, which allows us to offset the tree later. When we have surveyed all the tagged trees visible from the station, we survey paths running through the area, spot heights of any areas without trees or paths in them, and traverse points to which we might later move the station. Then we set it up at another point, and do it again.

While we're at the Arboretum, we may take care of other tasks such as locating old control points, resurveying trees previously missed, or surveying the elevation of areas that were missing data.

When we're done for the day, we pack up and take the total station back to PSB, where we download the station data in both txt and dxf formats, and enter the field data from the notebook into a spreadsheet, tying it to the records we have from the Arboretum. We use Autocad to view and check the accuracy of the station data, and to draw and offset tree circumferences.

Cartography  

As we gather increasing amounts of field data, we may want to think more this semester about how to organize and represent it. Addressing the problem of how to map plants at intelligible scales could involve working both on paper maps and on re-scalable digital maps, exploring the use of Flash and Zoomify for the latter. We may look at the possibility of building a mapserver to index plant collections in the Arboretum and across the island.

Other possibilities

While our main project will be further mapping the trees of the Arboretum, we could also think about exploring some smaller exercises, such as mapping the island-wide “exceptional trees of Honolulu,” looking at plants on the UH campus, and/or mapping in one or more of the city’s community gardens. Because the workgroup is organized throught separate independent studies, it could potentially include people pursing different particular projects within it. All participants should plan to meet at least once weekly to stay abreast of each others’ activities, and to coordinate times to carry out field observations. We may also set up times to consult a number of experts, such as Ray Baker at the Arboretum, and Lyndon Wester regarding community gardens.

Participation  
If you have an interest in mapping plants, surveying in the Arboretum, and working on a collaborative mapping project, please consider joining us. Experience in field mapping (i.e. Geog 472) is preferred but not requisite, and participants should be familiar with basic mapping concepts.

Participants should be prepared to:
  • meet weekly for both survey work and data processing
  • work outside regardless of the weather
  • work on weekends and holidays if need be
  • commit to a high degree of accuracy
  • spend some time processing the field-data
This can be taken as a class for 1-3 credits, depending on the amount of time you plan to spend on it. For more information, please contact David Strauch or Ev Wingert (advisor).
Trees surveyed:  
2009 crew  
Julius S Paulo
Borjana Lubura
Travis Niederhauser
Keith A Bettinger
David Strauch


Manoa TMK parcels near Lyon Arboretum