Pacific Southwest Region

Types of Inventory Compilations

Periodic Updated Inventory

Vegetation maps were overlayed with the plot locations to determine the map label associated with the subplots. Plot locations consisted of samples on the 3.4 mile systematic grid plus intensification plots for rare forest types and plantations. Intensification sampled plot intensities vary by National Forest. Only those subplots targeted as intensified types and conditions were used along with all 3.4 mile grid plots, and on-targeted types were assigned 'DRP' (Drop) strata. Strata, map labels, split condition codes, and sites were assigned. Once map labels were determined and merged with the inventory files they were expanded to per acre values. After the inventory was summarized, some strata were lumped into similar strata to reduce standard error. For map strata without plots, estimates were borrowed from adjacent Forests where needed.

Periodic Update with Growth Projected Inventory

Periodic Inventories were updated with the latest vegetation map and inventory mortality data. The tree mortality and removal information was collected in the field on FIA plots. Vegetation maps were overlayed with the plot locations to determine the map label associated with the subplots. Plot locations consisted of samples on the 3.4 mile systematic grid plus intensification plots for rare forest types and plantations. Intensification sampled plot intensities vary by National Forest. Only those subplots targeted as intensified types and conditions were used along with all 3.4 mile grid plots, and on-targeted types were assigned 'DRP' (Drop) strata. Strata, map labels, split condition codes, and sites were assigned. Once map labels were determined and merged with the inventory files they were expanded to per acre values. After the inventory was summarized, some strata were lumped into similar strata to reduce standard error. For map strata without plots, estimates were borrowed from adjacent Forests where needed. The Forest Vegetation Simulator (FVS), was used to grow individual tree data forward to a common year. Previous growth measurements were used to calibrate diameter growth multipliers.

Annual Inventory

Annual Inventories were compiled using the latest vegetation map and available inventory data. Plot locations intersected with the vegetation map was used to determine maplabels for each subplot. Plot locations consisted of all available annual FIA hex and intensification plots. For annual inventories, 10 percent of the forested FIA Hex plots are measured each year, each plot represents a 6000 acre hexagon area. Intensification plots and non-forest hex plots were measured in one field season. Intensification sampled plot intensities vary by National Forest. Only those subplots targeted as intensified types and conditions were used along with all hex plots, and on-targeted types were assigned 'DRP' (Drop) strata. Strata, map labels, split condition codes, and sites were assigned. Once map labels were determined and merged with the inventory files they were expanded to per acre values. For map strata without plots, estimates were borrowed from similar strata on the same or adjacent Forests where needed.

USDA Forest Service - Pacific Southwest Region
Last Modified: Friday, 13 April 2012 at 13:20:51 EDT