Changes in hardwood volumes across the U.S. South following updated NSVB equations

December 21, 2023 David Rossi

by David Rossi and Ray Sheffield

In a previous post, I highlighted recent updates to the FIA inventory estimation methodology on privately held pine timberlands in the U.S. South. In this post, I will highlight the impacts of this change in methodology on privately held hardwood timberlands, focusing on only Growth Stock estimates of inventory, growth, and removals. I will focus on states in the U.S. South where no new survey information is available, but rather only an update to volume estimation methods (Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, East Texas, and Tennessee). In Tables 1 through 8 below, Inventory (“INV”) and Removal (“REM”) estimates are provided in MCF while average Growth per Acre (“AVG. GPA) is reported in cubic feet per acre. Version 37a data (“v37a”) refers to FIA summaries prior to the update to the volume estimation methodology while version 2023b (“v2023b”) refers to summaries after the change.

Hardwood inventory changes are the largest in Tennessee. Hardwood inventory is estimated to be 12.9% larger under the v2023b summary. Growth and Removals are estimated to be larger as well. Across the U.S. South, hardwood inventory, growth, and removal changes are largest in central Tennessee (+16.5%, +12.7%, and +16.1%), the plateau region of Tennessee (+14.6%, +12.3%, and +15.3%), east Tennessee (+13.7, +11.3%, and +15.2%), and west-central Tennessee (+13.7%, +8.9%, and +13.7%). Removals are also notably estimated to be larger in west Tennessee (+7.1%).

Other notably large changes in hardwood inventory volume occur in the Ozark region of Arkansas (+8.3%), north Alabama (+7.3%), north Georgia (+5.3%), north-central Alabama (+4.6%), and the Ouachita region of Arkansas (+4.1%).

Changes to estimates in hardwood growth per acre are also particularly large in north-central Alabama (+4.6%), north Alabama (+4.4%), north Georgia (+3.8%), and west-central Alabama (+3.6%). Growth per acre is only estimated to be lower in the south-Delta region of Louisiana (-1.9%), the south-Delta region of Arkansas (-1.7%), northeast Florida (-0.9%), and Central Florida (-0.7%).

Other notable changes in estimates of hardwood removals occur in the Ozark region of Arkansas (+7.3%), north Georgia (+7.2%), the north-Delta basin in Arkansas (+7.1%), and north Alabama (+6.9%).

For summarization of changes across different age classes, ownership groups, and forest types, contact David Rossi (drossi2@ncsu.edu).

Table 1: Alabama (Hardwood)