Analyzing forest health data
This report focuses on the Forest Health Monitoring Program’s development and use of analytical procedures for monitoring changes in forest health and for expressing the corresponding statistical confidences. The program’s assessments of long-term status, changes, and trends in forest ecosystem health use the Santiago Declaration: “Criteria and Indicators for the Conservation and Sustainable Forest Management of Temporate and Boreal Forests” (Montreal Process) as a reporting framework. Procedures used in five aspects of data analysis are presented. The analytical procedures used are based on mixed estimation procedures. Examples using the indicators are included, along with a clear link to the analytical procedures used (1) estimating change over time within groups—estimation of growth, harvest, mortality, and crown condition; (2) testing for differences in change over time among groups—foliar transparency; (3) estimating change using covariates—impact of drought on change in foliar transparency; (4) estimating plot values for unmeasured years—comparison of observed and predicted (Best Linear Unbiased Predictions) values of foliar transparency, dieback, and total volume; and (5) estimating tree heights—examples of using estimated tree heights to estimate tree volume.