Guest Blog by Tim Salkeld, Ministry of Natural Resource Operations, Forest Analysis and Inventory Branch
The province manages its natural resources with a number of very large data sets, all made available through the BC Data Catalogue. Keeping data current and relevant for durable decision making requires a great deal of effort by the data custodians and support by DataBC.
BC’s forests are described by a spatial layer with attribution that provides estimates of the species composition, age, height, basal areas, volume, and biomass for distinct forest stands. It consists of over 4.5 million spatial shapes covering the province from mountain top and ice fields to valley bottoms and urban interfaces. It is used for determining timber availability, for conservation and habitat analysis and any number of other analysis from a provincial level down to individual polygon.
The data is available here:
Over the last two years the inventory has been updated to account for the large natural losses due to the Mountain Pine beetle (MPB) and for wildfires since 2007. It also reflects the integration of a LiDAR project on northern Vancouver Island to improve the estimates of stand height and a Landscape Vegetation Inventory in the Cariboo. This link https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/forestry/stewardship/forest-analysis-inventory/data-management/mpb_changes_to_veg_2015.pdf provides in-depth details of the methodology used for the adjustment made to the provincial forest cover.
The methodology used to account for the MPB changes to the inventory for the past 5 years had been accomplished by projecting the inventory attributes, calculating volume and then depleting the projected inventory volume by the MPB predicted mortality. This process is documented here https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/forestry/stewardship/forest-analysis-inventory/data-management/mpb_changes_to_veg_original.pdf. This methodology required a great deal of manual intervention and changes to stand structure were only reflected in the forest tree volumes and stand density and not to the stand species composition, basal area, or other stand attributes.
In the Provincial Forest Inventory release, we have implemented some infrastructure changes to the operational database (VRIMS) and projection model (VDYP7) to accommodate the changes for the MBP impacts. First a new Layer ‘D’ or dead layer was created in the VRIMS operational database. This uses the same data model as is used for new inventories to be able to keep track of dead trees in inventory stands. Changes to the natural stand projection tool VDYP7 were done to allow the calculation of the stand volume for the live and dead layers.
The forest inventory release includes our standard data product as well as a few new products as described below:
VEG_COMP_LYR_R1_POLY (our standard product) provides the estimates of forest inventory for the rank 1 tree layer. This is the workhouse dataset for almost all analysis and it has the total dead volume for the polygon identified in the attribution as well as the attribution for the dominant (Rank 1) stand composition.
The VEG_COMP_POLY and the VEG_COMP_LAYER: are new table products that will provide analysts with the spatial forest cover estimates for all layers identified including the Dead layer (Layer_D). This provides more information for the stands following the MPB outbreak, other stands with a significant dead component from other causes, and other live tree layers that were not provided to the public previously requires the use of a one to many join to the polygon for analysis.
This release of the Forest Inventory differs from the 2014 Forest Inventory reflecting changes in growing stock of the forests, in areas updated for harvest and fire and for attribute adjustments to account for the MPB. The overall impact of these changes and the change in methodology for MPB results in an increase to live stand volume of 215 million m3 and a reduction to dead stand volume of 272 million m3 for a net total volume reduction of 64 million m3 or 0.6% of the total volume.
Questions about the forest cover and adjustment process can be forwarded to
Tim Salkeld RPF A/Manager Inventory Forest Analysis and Inventory Branch, B.C. Ministry of Forest, Lands and Natural Resource Operations Ph: 250-387 3650 Fax: 250-387 5999 Email: Tim.Salkeld@gov.bc.ca
Marc Rousseau RFT Team Leader, Forest Inventory Update Forest Analysis and Inventory Branch Ministry of Forests, Lands and Natural Resource Operations 441 Columbia St, Kamloops, BC V2C 2T3 Ph: 250-828-4426 Email: Marc.Rousseau@gov.bc.ca