Anyone who lives in or has visited the City of Pine Lake will notice the many large beautiful trees that are interspersed throughout the city. The City of Pine Lake’s leadership and citizens have expressed a keen interest in protecting and preserving this wonderful natural resource with which the City has been blessed. This is evidenced by the City adopting its first Tree Protection Ordinance on August 13, 2007. 

 

Tree canopy cover is one of the most basic and useful descriptors of the urban forest. Tree canopy is the spread of the live crown of a tree and tree canopy cover is the percentage of land area covered by tree canopies. By periodically measuring canopy cover, communities can assess the effectiveness of ordinances and other management methods aimed at maintaining or increasing tree canopy.

 

To help gauge the health and status of Pine Lake’s community forest, the Tree Authority Board commissioned a Tree Canopy Assessment. A tree canopy assessment involves a determination of the percentage of ground surface in a municipality or other entity that is covered by trees. A canopy assessment can be used to determine changes in the tree canopy as well.

 

The objective of this tree canopy assessment is to determine the current percentages of land cover in Pine Lake in four categories: 1. tree canopy; 2. impervious surfaces; 3. grass or open fields; and 4. water. Percentages of the various types of land cover will be determined from 13 years ago (1995) to determine the change in types of land cover. The change in types of land cover will be used to establish initial trends in land cover change and the current land cover assessment can be used as a benchmark to determine future changes. 

The City of Pine Lake recognizes the benefits derived from the conservation, proliferation, and renewal of trees and increased canopy which includes:

To determine the percentages of the four categories of land cover, aerial photographs of the City of Pine Lake taken in 1995 and 2007 were used. The aerial photographs were obtained from the Geographic Information Systems Division of the DeKalb County Planning and Development Department. 

 

A photo-coordinate grid (clear acetate overlay with evenly spaced dots inside .25 inch x .25 inch squares) was placed over the aerial photographs and used to determine the percentages of the four types of land cover. Approximately 3400 samples points (dots) were tallied for each of the aerial photographs. The sampling is the equivalent of approximately 5 sample points per acre.

 

Each sample point was tallied as either tree canopy, impervious surface, grass or open field, or water. A determination of the category was made for each sample point based on 50 % or more of the .25 inch x .25 inch square being occupied by the particular land cover type.

 

The most significant change in land cover from 1995 to 2007 was the increase in impervious surface, which increased from 18.4 percent to 22.5 percent (see Table 1.). This is to be expected as development has increased in Pine Lake as it has in other cities in the metropolitan Atlanta area. 

 

The most surprising finding in the assessment was the fact that the tree canopy cover has remained basically the same during the 12 year period (approximately 66 percent). This can be explained in part by the fact that while there has been some clearing of trees for development, the remaining trees have grown during the 12 year period and their canopies have expanded. In addition, some of the open areas appear to have been reforested. An example is the 20 acre area just north of Rockbridge Road (See Aerial Photographs).

 

While the tree canopy has remained essentially unchanged during the period 1995 to 2007, it is anticipated that the potential for a decrease in canopy coverage is high. The reason for this is the trend in the increasing number of building permits. In the period 1995 to 2007, a total of 154 building/new construction/additions permits (12 per year) were issued. It is expected that this number will increase and thus tree canopy coverage could begin to decline. In addition, many of Pine Lake’s tree are mature and over-mature, which means many trees may decline and die in the next 10 years. Of course, the Pine Lake Tree Conservation Ordinance adopted in August 2007 should prevent any significant decline in tree canopy coverage.

 

To keep track of the trends in tree canopy coverage, it is recommended that another tree canopy study be performed in five years (2013). This will in part give an indication of the effectiveness of the Pine Lake Tree Conservation Ordinance.

 

Based on the results of this Tree Canopy Assessment, the percentage of tree canopy cover in the city has been maintained at a healthy level of approximately 66 percent. There has been a slight decrease in the percentage of tree canopy coverage from 1995 to 2007, which is primarily due new construction. Since the City of Pine Lake’s Tree Authority Board is committed to strict enforcement of the Tree Conservation Ordinance, Pine Lake’s trees will be protected and preserved and new trees will be planted to replace trees that may have to be removed during construction or other activities; therefore, the tree canopy coverage in Pine Lake should be maintained at the current level of 66 percent.