Data

Data from the FIA soil indicator were designed to address specific questions identified under the Montreal Process. However, these data also may also provide useful information for researchers and others interested in the current status of America's forests.

Where can I find the Soil Data?

As data become available, they will be posted at FIA's National P3 data site. Please check this site frequently for updated information and data availability.

Changes to Methods

As with any new research program, modifications to the sampling and measurement protocols are a necessary part of indicator development and implementation. During the first five years of the soil indicator (1998-2002), evaluation of quality assurance data along with feedback from the field crews, regional trainers, and lab personnel resulted in a series of improvements to the measurement protocol that have enhanced both the efficiency of the program and the data quality. However, these changes also complicate the analysis of data collected across multiple field seasons.

Understanding the changes in the field and laboratory methods is critical to the correct analysis and interpretation of results. As a result of changes to the field and laboratory protocols, soil chemical values from samples collected in 1998 and 1999 are not directly comparable with those obtained from samples collected since 2000. In general, combined data from these first five years of implementation should not be used to develop baseline statistics for state or regional reporting.

• Changes to erosion and compaction measurements (pdf 53K)
• Changes to soil sampling methods (pdf 51K)
• Changes to laboratory protocol (pdf 52K)
  

Examples of Core Tables and Products

The following are examples of how soils data may be presented in future FIA reports:

• Example core table for Erosion and compaction data (pdf 33K)
• Example core table for soil physical properties (pdf 24K)
• Example core table for soil chemical properties (page 1) (pdf 25K) (page 2) (pdf 23K)

Conversion Factors

Elemental data from soil analyses are typically expressed in units of concentration (e.g., %, mg kg-1, cmolc kg-1). However, because plants exist within a volume of soil, units of volume may be more ecologically meaningful for addressing forest health questions. Conversion of concentration data to volumetric units is done using the soil bulk density (g soil per unit volume).

Download a summary of conversion factors for soil chemical data. (pdf 52K)