HONORS RESEARCH THESIS

CHARACTERIZING TREE COVER CHANGE IN WORCESTER, MA

 

PURPOSE

 

Urban tree cover extent in the Greater Worcester area has changed dramatically over the last seven years following the discovery of the invasive wood-boring Asian Longhorned Beetle (ALB) in 2008. The ALB eradication strategy caused the removal of 30,000-plus host trees, to date. The majority of the ALB host trees (>80%) were removed from two neighborhoods in north Worcester (i.e., Burncoat and Greendale). In response to the ALB eradication strategy, a multi-agency urban reforestation effort involving the City of Worcester, Massachusetts Department of Conservation and Recreation (DCR), and Worcester Tree Initiative (WTI) began in 2010.

METHODS

 

This study characterizes the amount of tree cover change between the start of the tree planting initiatives, 2010, and the present day, 2015, in Burncoat and Greendale neighborhoods. WorldView-2 satellite imagery (0.5 m) is used in concert with in situ tree inventory and 1 m airborne LiDAR data to create a 2015 tree cover map using an object-based classification approach. The 2015 tree cover map is compared for areas of gain and loss to an existing tree cover map from 2010.

 

RESULTS

Results show a 7.52% increase and a 0.46% in loss in tree cover from 2010 to 2015. The DCR tree planting contributed to a 1.75% in gain in tree cover and 0.032% of the trees planted by the DCR were lost in 2015 from a total of 12,423 trees planted from 2010 to 2012. The results of this study will help inform agencies (e.g. DCR and WTI) engaged in monitoring urban tree cover the utility of a top-down approach integrating fine spatial resolution imagery with LiDAR and GIS layers (e.g. impervious surface) to understand the early impacts and success of reforestation efforts.

The research paper for the project can be viewed here.

DATA

BACKGROUND

RESULTS

Tree cover change map from 2010 to 2015 indicating gain, loss and no change in tree cover

EXAMPLES OF TREE COVER LOSS

EXAMPLES OF TREE COVER GAIN

OPTIMIZED HOTSPOT ANALYSIS FOR TREE COVER GAIN

Optimized Hotspot Analysis in Burncoat and Greendale, highlighting hotspot locations of tree cover gain by Maiden West Boylston Street in Greendale (top right) Clark and Burncoat Street (bottom right).

OPTIMIZED HOTSPOT ANALYSIS FOR TREE COVER LOSS