If surveys are timed to coincide with periods when disease or insect pest problems are most obvious, it may be relatively easy to document the extent and incidence of the problem. For example, leafy mistletoe in deciduous trees is easily rated in the winter months, whereas branch dieback in alder caused by flatheaded borers is most obvious in summer. However, more detailed data, such as categorization by species, may require highly trained evaluators, especially in areas where a wide variety of tree species are used. For many, though not all tree species, diameter serves as a useful indicator of tree age. Empty planting spaces, sidewalk displacement, and other obvious site characteristics can be tallied.
Some cities prohibit tree topping in order to maintain trees in good health and a safe condition.
Before deciding to enact such a provision or adopt other management actions, it would make sense to collect some base line data on the prevalence of this undesirable practice. We conducted a preliminary windshield survey to determine the incidence of tree topping in residential areas of the City of Vacaville. Twelve sample plots were established using randomly-generated coordinates as described under Sampling Considerations For Photogrammetry . From the intersection nearest to each random point, we traveled a predetermined route for a distance of about one-half mile, which generally allowed at least 40 trees to be tallied. We looked at mature hardwood trees in front and side yards, and tallied the total number of trees with and without evidence of topping.