Every Tree Counts: Using PhillyTreeMap for Collaborative Urban Forestry

GIS Contributor


A Collaborative Effort

From the beginning, collaboration has played an important role in the PhillyTreeMap project.  Azavea partnered with Philadelphia Parks & Recreation, the Pennsylvania Horticultural Society (PHS), and the Delaware Valley Regional Planning Commission (DVRPC) to gain important design feedback throughout the iterative software development process.  It was important for Azavea’s developers to understand what features these organizations thought were important in a wiki-inspired tree inventory application and what needed to be simplified or changed in order to make PhillyTreeMap as intuitive and user-friendly as possible.

Philadelphia Parks & Recreation, the Pennsylvania Horticultural Society and the Township of Lower Merion all contributed copies of their existing tree inventory data for inclusion in the PhillyTreeMap database, and will share the management and monitoring of the system.  These data sets served as the start the tree mapping process.  As part of rectifying multiple data sets, Azavea created methods for identifying and eliminating overlapping data points to prevent the entering of duplicate trees into the system.  For example, PhillyTreeMap specifically flags those points which have a spatial proximity within the bounds of a pre-set parameter, such as within five feet of a documented existing tree.  After some initial field testing and experimentation by its partner organizations, Azavea expanded this proximity from five to ten feet and included some additional provisions for data points originating from the same dataset.  Implementing these changes enabled PhillyTreeMap to reduce the total overlap across all datasets to 0.69%.

PhillyTreeMap enables registered users to add information about trees. As new information about each tree is added to the system, the completeness percentage is automatically updated to reflect the status of the tree’s record. The detail page also provides aerial and street level views of the tree’s location.

The PhillyTreeMap website is built on open source code contributed by the Urban Forest Map project in San Francisco.  Azavea was able to build upon this established foundation and add many new features, including the user reputation system, a redesigned Add-a-Tree page, customized user groups, support for several new data fields, redundancy checks to eliminate duplicate entries, a public commenting system, robust search capabilities, and a more flexible, data-driven Tree Key database that can be adapted to multiple locations.  Azavea also integrated OpenLayers, an open source mapping library that enables PhillyTreeMap to support multiple base map options.  These enhancements are being merged with the original Urban Forest Map code base and will be published as an open source project in mid- 2011.

Looking Ahead

Azavea and Urban Ecos, the group behind Urban Forest Map, continue to work together to update Urban Forest Map with the newly developed features from PhillyTreeMap as well as to roll out a new implementation for the Sacramento region.  There has been interest from a number of communities both in the United States and internationally in using the project code to implement other similar systems.  With limited resources available to many horticultural and municipal groups, this type of wiki-inspired map-based project can help organizations and governments collaborate with the public to create a useful and data-rich tree inventory.  Just as the data collected by the decennial census is used to allocate billions of dollars in federal funds to local communities based on need, the data collected in a tree inventory can be used by communities to facilitate strategic decision-making policies and long-term resource allocations regarding the composition, condition, and distribution of the urban forest.

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Article by By Mary L. Johnson and Deborah Boyer of Azavea.  


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