Arboriculture & Urban Forestry 42(3): May 2016 Physical Inventory of Each Block A physical inventory card was used to collect on- site data at the block level. The block is defined as the area between the faces of the buildings on each side of the street, extending laterally to the middle of the crossing street. Other block features captured in the inventory include the condition of the sidewalk, estimated height of the tallest building, and the presence or lack of front porches. Notes were made of geographi- cal features, such as hot spots (bars, convenience stores, and check-cashing establishments), ad- jacent treed streets, nearby shopping districts, nearby parks, and security cameras. The neigh- borhood was rated for upkeep (a rating with the subcategories of gentrified, tidy, graffiti), social order (presence of litter, and loitering, drinking, drug sales, prostitution) and the pres- ence of abandoned cars, boarded windows, or property damage. The following list was nar- rowed down to five block characteristics and summated to a single score, Block Features: 1. sidewalk condition 2. presence or lack of front porches 3. level of block upkeep 4. social order 5. physical signs of decline Three measures of tree cover were gathered: 1. The count of street trees. Street trees are usu- ally planted by the municipality, or the resident, in the sidewalk in spaces cut from the concrete or in strips along the curb prepared when the sidewalk was installed. This count was made by visiting the block. 2. The count of total trees. All trees with can- opy extending into the facing block area, including street trees, made up the count of Total Trees. This measure of tree frequency was also calculated by physically visiting the block. This count includes street trees and the adjacent trees not growing in sidewalk planting basins. Some Wilmington blocks have small front yards. Trees growing from these private spaces were included. Essentially, any plant with a canopy and an upright trunk height of more than 1.52 m was included in the count of Total Trees. Trees on side streets not extend- ing into the facing block area were not included. 3. The percent canopy cover. Canopy cover was calculated from aerial photographs of each 149 block. Aerial photographs downloaded from Google Earth and Microsoft Bing were super- imposed on a grid. Once the total number of grid squares comprising the facing block was calculated it was possible to count just the squares over the tree canopy. The percent can- opy cover is the number of squares over the trees divided by the total squares on the facing block. The three tree measures, Street Trees, Total Trees count, and percent Canopy are related measures, but each captures something a little different from the other. To understand the impact of trees on stress, it is important to have the most accurate measure possible. To refine the measures one step further, Street Trees was sub- tracted from Total Trees to produce an Other Tree measure. This is the count of trees growing in the alleys, on the front lawns and extending into the facing block from adjacent streets. Table 1 shows how these four measures are related. Since Can- opy is strongly related to Total Trees, and Street Trees and Other Trees are two components of the total, Street Trees and Other Trees were used in the analysis as measures of trees. The breakdown into these two types allows for separate effects of trees based on what the municipality can influence and what homeowners can influence. Table 1. Correlation between tree cover measures. Total trees Total trees Street trees Other trees Canopy 1.0000 0.8014 0.6051 0.7738 1.0000 0.0091 0.6653 1.0000 0.4077 Street trees Other trees Canopy 1.0000 Secondary Data Source A secondary source of data was used for median in- come of the block. The study authors had concern that a possible correlation between median income and neighborhood stress would provide an alter- nate explanation for the effect trees have on stress at the block level. By factoring median income into multiple regression analysis, a control for its impact was added. The authors would have preferred to use median income drawn from U.S. Government census data, however, the smallest geographic unit available is the census tract. The census tract is too large a unit of measure for evaluating the impact of tree cover on neighborhood residents. As an alter- native, a Wilmington cross-reference directory was ©2016 International Society of Arboriculture
May 2016
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
