Annual Inventory and Other PNW-FIA Issues
by Sue Willets
Program Manager PNW-FIA Program
Timely forest inventory information and analysis are critical to the management and
protection of the forests within the US. The US Forest Service National Forest Inventory
and Analysis program has been responsible for conducting a comprehensive inventory of
forestland within the US since the 1920s. Permanent grid plots have been installed
in the West Coast states since the 1960s by the USFS PNW Research Station with the
goal of re-measuring the plots every 10 years. Because of limited budgets, which have
eroded over time, and a focus on broadening the inventory to measure more than timber
variables, it has been difficult for the PNW FIA program to consistently complete the
inventory on a 10-year cycle.
The American Forest and Paper Association has organized two Blue Ribbon Panels (1991
and 1997) to review the national FIA program and provide recommendations to the Forest
Service on needed changes to the content and capabilities of the program. The most recent
panel recommended that the Forest Service should 1) elevate the priority of FIA in the
Forest Service program, 2) convert the FIA program from a periodic inventory to an annual
inventory, 3) fulfill the congressional mandate of reporting on all lands regardless of
ownership, 4) concentrate on the core ecological and timber data, and 5) develop a
strategic plan to implement the full FIA program.
The National FIA program has been interested in annual inventory since 1992, when
development of a prototype system was initiated in Minnesota, in conjunction with the
Minnesota Department of Natural Resources. The system used remote sensing to identify
areas where change had occurred and plots were located in areas of change as well as a
percentage of the unchanged plots. In 1996, the Southern Research Station in cooperation
with state partners piloted a much simpler system in which each plot had an equal
probability of being sampled and 20% of the plots were measured each year. The Southern
method was based on 5 overlapping panels that were equally distributed across
each state. The panel system is being used as the model for annual inventory throughout
the rest of the contiguous 48 states. Advantages of this method of annual inventory
include having an annual update to the inventory in every state, having boundary
less data that is consistent across state lines, being able to add variables to be
measured to all states at the same time, and giving partners the opportunity to
participate in the inventory on a more regular basis. One major difference is that the
traditional change analysis work that compares data from two different inventories will be
replaced with a rolling average estimate of change. This method may reduce or delay the
detection of changes in the resource, on the other hand the periodic re-measurement only
estimated change every 10 years.
In 1998 the Research Title to the Farm Bill gave the Forest Service legislative
direction to develop a strategic plan that 1) outlined conversion to a 5-year annual
inventory within 5 years and 2) included a budget for the inventory. Congress accepted the
plan and a modified inventory cycle that is 7 years in the East and 10 years in the West.
The target for implementation of annual inventory across the nation is 2003.
Current plans for implementation of annual inventory in Oregon, Washington, and
California by the PNW Station are to complete a baseline periodic inventory that can be
used to calculate the final change analysis for periodic inventory and serve as the basis
for modeling forward the panels that would not be measured for the next 5 to 10 years.
Because we have just finished an annual inventory in Oregon we have chosen to implement
our first annual inventory in Oregon in the field season in 2000. We will be accelerating
the collection of the baseline inventory in Washington and California over the next 3
years by only re-measuring 60 percent of the plots. This will allow us to estimate the
timber volume and area within acceptable statistical variation while still meeting the
goal of annual inventory by 2003. We hope to start annual inventory in Washington in 2001
and in California in 2002. We were provided budget increases in 2000 to accelerate the
transition to annual inventory and if the budget increases continue we are confident that
the conversion will be successful.
Additional changes to the PNW program include increasing the plot intensity to one plot
every 6000 acres, using a national core field data collection manual that outlines the
timber variables that will be measured consistently across the nation, and implementing a
standard plot design has been adopted nationally. Ecological variables are also being
established for national consistency that will be measured on a sub-sample of the plots
during the summer season. Additional regional variables will continue to be measured at
the regular plot intensity.
One of the remaining areas that still needs to be worked out is the inconsistencies
between the inventory currently being conducted on National Forests in Oregon, Washington,
and California and the inventory outside of National Forests. These are the only states
where NFS and FIA inventories are implemented with different designs and administered
separately. The PNW Station is responsible for all lands outside of the National Forests
and some BLM lands. The Pacific Northwest Region and the Pacific Southwest Region of NFS
conduct their own inventories on National Forests. While efforts are underway to evaluate
the potential for modifying the current NFS system to produce outputs commensurate with
those produced by FIA, there continues to be pressure from FIA constituents to implement
the FIA system across all ownerships (as specified in the Blue Ribbon Panel report and the
1998 Farm Bill).
While any transition period is hectic and sometimes stressful, we are looking forward
to the time when the details of the inventory itself are more stable and we can
concentrate efforts on the analysis and research components of the system. PNW has
recently filled some key analyst positions and is working on developing a research plan
that outlines the scope and priorities for research on broad scale policy relevant issues.
We are also actively engaged in developing comprehensive databases on coarse woody debris,
under-story vegetation, and land use change and using these databases to assess habitat
extent and condition, non-timber forest products, and effects of land use laws on timber