Annual monitoring of US timber production

The Forest Inventory and Analysis (FIA) program of the US Forest Service (USFS) includes a survey-based data collection and reporting effort known as Timber Products Output (TPO). The TPO program surveys wood-using manufacturing facilities to estimate production of roundwood from forests by county. This information, in conjunction with inventory plots measured in forests, is crucial for monitoring forest growth and harvest, evaluating the impact of emerging markets, and assessing the sustainability of wood utilization in the US.

Traditionally, the TPO program has been based on periodic surveys conducted state-by-state every few years. The US Forest Service is moving to a sample-based annual survey that will improve timeliness and efficiency, and will enable statistical estimation of uncertainty. NCASI staff have been working with the USFS to evaluate alternative sampling and estimation approaches. A simulation of different approaches showed that stratified random sampling offered more flexibility and simplicity while producing comparable accuracy compared to other approaches.

The TPO program will begin implementation of annual sampling in a few states in 2019. Results of the sampling study have recently been published in Forest Science. The abstract follows.

Understanding roundwood production in the United States at fine spatial and temporal scales is needed to support a range of analyses for decision making. Currently, estimates of county-level roundwood production are available at various time intervals for different regions of the country and for different products. Here we present our reasoning for moving to an annual timber products monitoring program and further present a comparison of sample designs to facilitate an annual program without increased effort. We found that both probability proportional to size and stratified simple random sampling designs were viable options, but the stratified simple random sampling design provided more flexibility. This flexibility was deemed important to target emerging markets and to enable sampling with certainty of specific firms. Our results lay the foundations for moving to an annual timber products output monitoring design in support of market, sustainability, and policy analyses as well as projections.

Reference

Coulston, J.C., J.A. Westfall, D.N. Wear, C.B. Edgar, S.P. Prisley, T.B. Treiman, R.C. Abt, and W.B. Smith. 2018. Annual monitoring of US timber production: rationale and design. Forest Science, fxy010, https://doi.org/10.1093/forsci/fxy010.