Minnesota Forest Land Area Estimation Using National Forest Inventory Data

Abstract

The United States conducts a national forest inventory (NFI) for the purpose of providing information on the forest resources of the nation. The United States Forest Service, through the Forest Inventory and Analysis (FIA) program, administers the NFI in cooperation with state forestry agencies. NFI data and information are used by states to support forest management and policy decision-making. Here we review the sample design and estimation procedures of the NFI, with special emphasis on those aspects related to forest land area. Using the 2017 inventory data for the state of Minnesota, we compute an estimate of 17.7 million acres of forest land with a sampling error of 0.52%. Our estimate matches that published by FIA. This report documents the process of obtaining and organizing the data and application of formulae to compute the estimate and associated estimate of sampling error. All data and calculations are assembled in an MS Excel worksheet as a resource for anyone seeking to develop a fuller understanding of this important data set and appropriate estimation procedures. We then extend the estimation to that of ash forest land area, information needed for assessment of potential impacts of the emerald ash borer. For 2017, we estimate that ash (black, green, and white) is a component (at least some live volume) on 4.33 million acres, is 25% or more live volume on 1.78 million acres, and is 50% or more of live volume on 1.10 million acres of forest land in the state.