| This study assessed the extent to which California's municipal forests were at risk from pest and disease threats. The two main tools used in the analysis were: Pest Vulnerability Matrix, a Microsoft Excel spreadsheet that illustrates pest-host interactions and overlap; and the US Forest Service's i-Tree Streets computer program that quantifies and monetizes municipal forest benefits and costs. The assessment applied these tools to data from 30 California municipalities' tree inventories. A report card concept was developed to identify and prioritize forest traits contributing to the population's vulnerability to loss. The analysis focused on four indicators: species/size diversity, age diversity, pest threat, and potential asset loss. We assigned letter grades (A-F) to each of the four indicators and a final grade to each city. Letter grades were determined from data such as: importance values, relative abundance of each taxon, age class distribution (juvenile, semi-mature, mature, senescent), pest scores, total benefit values and associated risk of loss. Also included in the assessment was data on the most severe pests, emerging pests, and counts of pests affecting the current inventory. The grades allow cities to compare themselves with other cities, as well as against an accepted standard. The report card reveals areas of proficiency and deficiency. Prioritized recommendations are presented concerning tree selection, monitoring, integrated pest management, and removal and replacement planning. The hope is that the report cards will promote greater awareness and more focused actions by managers to reduce the vulnerability of their municipal forests to pest threats. |
