A Microcomputer-Based Park Tree Inventory System

Mapping

Steps outlined below describe how trees were mapped and located in the field (also see McPherson, 1984).

1. Obtain or draw a base map(s) of the area to inventory. Draw to the same scale as vegetation data.

2. Obtain vegetation data. This may be in the form of existing planting plans or aerial photographs.

3. Check the scales of base map and vegetation data. They should be the same.

4. Decide whether to divide the area into smaller work areas. If maintenance crews are responsible for designated areas, then each area can be mapped separately. Alternatively, large areas can be divided into work areas defined by major sidewalks or roads.

5. Determine the appropriate grid cell size. Large grid cells may contain many trees. This makes identification of individual trees difficult. A 50 ft² grid was used in Central Park, NY (6) and a 20 ft² cell size was used at the USU campus. This cell size worked well because of the relatively small size of the study site, and the close spacing of trees in one work area. When selecting grid cell size, consider the variability in spacing of trees throughout the work area, the overall size of the area, and the expected amount of mapping error.

6. Draw the grid on mylar, which can then be overlayed on base maps, or draw it directly on the base map. Figure 1 shows the X-Y grid coordinates. The origin (X=0, Y=0) is in the southwest corner of the map.

7. Locate trees on the base map using aerial photographs, existing tree plans, or field measurements. Make prints to verify and update tree locations while conducting the inventory.

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Figure 1.

A map with grid overlay shows tree species and locations. X coordinates run south to north and Y coordinates run west to east

Although the mapping process appears complicated, it actually can be completed quickly if base maps and vegetation data are present at the appropriate scales. These are readily available in most cities.

Recording tree data

Data collected should pertain to the stated objectives of the inventory and should be recorded in a computer compatible format. Objectives of the USU case study inventory required information of sufficient detail to describe the structure, value and condition of the tree resource, and to estimate future maintenance costs required to substantially improve these aspects of the arboretum. Thus, a PTIS compatible recording format was developed to record the following:

• 1. Work area and sheet number — for cross-referencing

• 2. Species name — a six letter code (e.g., Acer rubrum 'Gerling’ = ACRUGE)

• 3. Grid coordinate location — X-Y values, respectively

• 4. Height — to nearest 5 ft.

• 5. Dbh — to nearest 1 in.

• 6. Age — estimated age class

• 7. Planting area — land cover types

• 8. Location code — 0-99 for value calculation

• 9. Condition code — 0-99 for value calculation

• 10. Pruning needs — heavy, light

• 11. Pruning operations — raise bottom, thin, etc.

• 12. Removal — new, in 2 yrs

• 13. Staking/bracing — remove, adjust, add

• 14. Insect control — yes, no

• 15. Disease control — yes, no

• 16. Fertilization — standard fertilizer, soil amendment

• 17. Irrigation — more, less

• 18. Visibility control — four obstruction classes

• 19. Root control — five damage categories

• 20. New tree planting area — four cover types

• 21. New tree size — three size categories

The inventory was conducted by landscape architecture students ($5/hr.). An average of 17 trees were inventoried per man hour, or one tree per 3.5 minutes. The estimated cost per tree was $0.30.

Data input

Students also assisted with data input ($5/hr.). Data were transferred from tally sheets to the computer database at a rate of one tree per minute. The average data processing cost was $0.01 7 per tree.

PTIS options

PTIS displays a master menu that allows selection of one of nine options. These options are briefly summarized below.

HELP provides general information on the program and specific instruction on the operation of each option.

INPUT allows the user to add new records to the database using the full screen editing capabilities of dBASE II.

EDIT permits corrections to be made to previously entered records. Specific tree records can be obtained directly if the tree’s identification number (SYSID) is known. Otherwise, the user can locate the erroneous tree record by providing species, work area, X and Y coordinates, dbh, and height. Records that meet requested criteria are displayed on the screen.

SEARCH enables the user to perform more sophisticated searches. Output can be directed to the printer for paper copy.

BROWSE utilizes the dBASE browse feature to edit the database.

HISTORY/UPDATE provides a record of operations performed on trees in the database. The Update procedure begins by locating the desired tree record and displaying the SYSID, work area, location, species name, dbh, and condition code. Condition code and dbh can be changed to reflect the effects of tree care operations on tree value, which is recalculated for each tree. Information on the crew, operation performed (e.g., pruning, fertilization), and further description can be entered (e.g., heavy pruning, liquid fertilizer). The date of operation(s) and time required to perform tasks are also requested.

REPORT provides summaries of database and tree record outputs. Summaries can include all or any specified part of the database. Output is displayed on the screen and can be printed on paper. Database summaries are programmed to provide specific information by species and dbh. The user can select from five database summaries.

Species Summary provides summary information on number, percent of total, average dbh, height, condition, value, total value of species, and percent of total value by species.

Species Composition and Age displays number, percent of total, number by age class, average age, dbh, and height by species.

Condition and Value provides information on number, percent of total, number by condition class, average condition and value, total value, and percent of total value by species.

Maintenance Needs presents counts of trees needing pruning, removal, fertilization, insect, and disease control by species.

Maintenance Needs by dbh provides maintenance by dbh class because maintenance costs are strongly correlated with tree diameter Table 1 shows number of trees needing specific maintenance operations for six dbh classes. Number of trees that need pruning, removal, insect control, disease control, staking, cavity/wound repair, fertilization, and root control are listed.

Three types of tree record output reports are available.

Individual Records provides species, work area X coordinate, Y coordinate, dbh, height, and value information for the specified tree record. If the SYSID is not known a SEARCH can be conducted.

Species Records presents the same information described above for each tree of the desired species. The report can also list only trees of the desired species that have a specified maintenance need, are located in a certain area, are greater than a specified size, etc.

Tree History Records lists the history data for a specified tree. Output consists of all operations performed on the tree and supplemental data recorded in the history database.

UTILITY contains a number of miscellaneous functions that provide additional information and flexibility to the user. For example, records of removed trees can be marked for deletion from the database without being deleted. The user knows what trees have been removed, and can still perform counts and searches to acquire more information on these trees.