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 1920’s. Permanent grid plots have been installed in the West Coast states since the 1960’s 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 management potential.