Forest Inventory and Analysis (FIA)

The U.S. Forest Service Forest Inventory and Analysis Program at the Pacific Northwest Research Station (PNW FIA) provides comprehensive information on forest conditions in California every year. The FIA program is a ground-based, permanent plot re-measurement system of the same trees over time, which captures and quantifies growth, removals and mortality well. It is repeatable and provides low errors.

The FIA program switched from a periodic to an annual inventory of forest land in California in 2001 by installing a complete sample of the state each year using 10% of the full set of plots. This equates to a complete sample of all inventory in California every 10 years, with completion of the first full annualized inventory of California forests in 2010. Between 2011-2020, FIA re-measured all plots. The current re-measurement cycle slated to begin in 2021 is being accelerated so that all re-measurements are completed in 5 years rather than 10 (i.e., temporal intensification). However, Covid-19 and wildfire impacts delayed completion of the second re-measurement cycle in 2020 and initiation of the intensified re-measurement cycle in 2021. These delays are anticipated to be resolved in the 2022 field season, but will result in the first accelerated re-measurement cycle to be completed in 6 years rather than 5-years. Despite this delay, the integrity of the data in the core FIA program is maintained while the state will continue to achieve intensification goals.


Why intensify?

Impacts from climate change, such as drought, insect and disease outbreaks, and wildfire, are becoming more frequent, intense, and larger in scale. The State also aims to increase the pace and scale of forest restoration. Reducing the FIA measurement cycle from 10-years to 5-years provides more frequent estimates of forest conditions, change and drivers of change, allowing forest managers to assess and respond to the effects of disturbance and management more rapidly.