Virginia, 2011 forest inventory and analysis factsheet
This science update is a brief look at some of the basic metrics that describe the status and trends of forest resources in Virginia. Estimates presented here are for the measurement year 2011. Information for the factsheets is updated by means of the Forest Inventory and Analysis (FIA) annualized sample design. Each year 20 percent of the sample plots (one panel) in Virginia are visited and measured by field crews, the data compiled, and new estimates produced. It is important that users keep in mind that in each year of new estimates, only 20 percent of the data are new, with the older data making up the remaining 80 percent of the sample. This may result in some spikes in estimates when comparing successive survey years, but in most instances the annualized design should give a reasonable indication of directional trends in the resource. After 5 years of measurements, the full sample complement (a cycle) is complete and a new survey cycle begins. The most reliable trend information (especially that concerning magnitude of change) comes from comparing two full cycles of data.