Part 3. Evaluating the urban forest and ordinance performance
As we discussed in
Developing
a Community Forest Management Strategy, two stages in the urban forest
planning process require the use of evaluation methods. To answer the questions
"
What do you have?" and "
Are
you getting what you want?", you will need to evaluate tree resources,
management activities, and public attitudes. Thus, evaluation methods are
important tools for formulating and monitoring tree management strategies.
In these pages, we discuss how various methods and techniques can be used
to evaluate tree resources and community forest management.
You can access our descriptions and examples of urban forest evaluation methods
either from the list below or by following the links from the page on Goals
for Community Forest Programs. Included in this section are methods for
evaluating tree resources, urban forestry management activities, and public
attitudes. Most of the techniques summarized here are well established, although
a few new applications and adaptations for urban forestry are included. Where
possible, we have provided examples to demonstrate actual applications of the
techniques described. Please contact
us if you know of other useful links or would like to see additional methods
covered.
The key to successful and efficient evaluation lies in focusing on what
needs to be evaluated. It is generally not desirable to collect more detailed
information than is likely to be used, since cost and effort generally
increase with the level of detail. On the other hand, it may be more efficient
to collect a variety of data in a single evaluation than to conduct a series
of separate evaluations. By following the process described under Developing
a Community Forest Management Strategy you should be able to determine
what types of data you will need to collect to meet your needs for information.
Methods for
evaluating tree ordinances and the urban forest ecosystem
* Sampling from populations. In many cases,
it will be more efficient to evaluate a sample of the population under
study (trees, parking lots, homeowners) than to evaluate the entire population.
Here we discuss how to develop a valid sampling scheme.
* Photogrammetry and remote sensing techniques.
Using stock aerial photographs or other aerial imagery, photogrammetric techniques
can be used to assess tree canopy cover quickly and cost-effectively. We discuss
the uses of photogrammetry and provide some examples of applications to ordinance
evaluation.
* Ground survey. For many applications, the
ground survey is still the simplest and most accurate means for collecting
detailed data on the urban forest. We describe basic ground survey methods
and a number of typical applications.
* Photo points. Photographs taken from the ground
or the air can provide graphic and obvious evidence of changes in tree
condition and cover. We discuss some considerations for establishing effective,
repeatable photo points.
* Record keeping and analysis. Well-maintained
records and databases can be analyzed to provide a wealth of information on
ordinance performance. We discuss the use of GIS, tree inventories, and other
records.
* Public polling. People are an integral part
of the urban forest ecosystem. We present a brief overview of methods used
to assess the opinions of the proverbial person on the street.
