Ground sample inventories

On this page

• Quality assurance of the data
• Data compilation
• Data access
• Permanent sample plots
• Provincial monitoring program 
• Vegetation Resource Inventory audits

The government is responsible for coordinating and managing data collection from 3 main ground sampling programs. These programs complement each other by providing unique data needed for making sustainable forest management decisions. More information about each program is provided in the pages below with associated sections that include links to data collection standards and reports.

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Quality assurance of the data

Data is collected by qualified independent contractors and Quality Assurance is carried out by Ministry employees who randomly select 10% of the plots in each contract to re-measure to ensure the data is within a certain threshold of accuracy (see standards and procedure documents for more information).

Data compilation

The data collected from inventory ground plots are processed using a set of compilation algorithms that estimate tree-level attributes such as height, age, basal area, volume, and site index, and summarize them at plot level. These algorithms also check and correct potential measurement or data entry errors. The compilation ensures that the compiled attributes are organized and stored in a consistent manner.

The data requirements, calculation, and procedures of compilation are detailed in the VRI Sample Data Compilation Process. The source code for compilation is available as an R package ‘FAIBCompiler’, on the B.C. government’s GitHub.

Data access

The data collected on inventory ground plots is Open Data and publicly available for download through the Forest Inventory Ground Plot Data and Interactive Map layer at the BC Data Catalogue webpage. Further, an interactive map shows the location of all plot types with custom queries to filter search results and easily download the subset of data of interest. For questions about the source data please contact Dan Turner or  Anya Reid.

Permanent sample plots (PSPs)

Permanent Sample Plots (PSPs) are purposefully located across a gradient of different forest types and are used to support development and testing of growth-and-yield models in unmanaged stands. They also provide a long-term biological baseline for how forest stands grow and develop. The main strength of this program is that it has been operational for over 90 years with some plots having 12 re-measurements. The subjective location of plots along a gradient of forest types is needed for model development, but limits the utility in monitoring average forest condition.

• Standards
• Reports

Provincial forest resource monitoring programs

Provincial forest resource monitoring programs include:

• Provincial Change Monitoring Inventory (CMI)
• Provincial Young Stand Monitoring (YSM)
• National Forest Inventory (NFI) programs.

These programs are provincial in scope and their plots are located on a standard 20 km grid or an intensification of this grid. These plots are measured at regular time intervals and use well known sampling methods. The main strengths of this program are the ease of re-measurement and statistically sound design using fixed-radius plots located at each grid intersection. It is important that these provincial programs are distinguished from location-specific CMI and YSM plots that have been established by forest companies in the past. This information can be found on these pages:

• Standards
• Reports

Vegetation Resource Inventory (VRI) audits

Vegetation Resource Inventory (VRI) audits are intended to verify key spatial inventory attributes estimated during photo interpretation, temporary plots are randomly established within mapped polygons in mature stands. Comparisons of this ground data to the photo estimation attributes helps determine confidence in the inventory for TSR. The main strength of this program is the efficiency in capturing variability within a polygon with the 5-point cluster plot design and the probability proportional to size with replacement (PPSWR) plot location. Its weaknesses are that the plots are not designed to be re-measured (which is often required) and  have limited flexibility in the use of the data. This information can be found on these pages:

• Standards
• Reports